Endangered and Threatened Wildlife and Plants; Endangered Status and Designations of Critical Habitat for Spikedace and Loach Minnow

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2010-0072; 4500030114]

RIN 1018-AX17

Endangered and Threatened Wildlife and Plants; Endangered Status and Designations of Critical Habitat for Spikedace and Loach Minnow

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Final rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), change the status of spikedace (

Meda fulgida

) and loach minnow (

Tiaroga cobitis

) from threatened to endangered under the Endangered Species Act of 1973, as amended (Act). With this rule we are also revising the designated critical habitats for both species. These changes fulfill our obligations under a settlement agreement.

DATES:

This rule becomes effective on March 26, 2012.

ADDRESSES:

This final rule and the associated final economic analysis and environmental assessment are available on the Internet at

http://www.regulations.gov

. Comments and materials received, as well as supporting documentation used in preparing this final rule, are available for public inspection, by appointment, during normal business hours, at the U.S. Fish and Wildlife Service, Arizona Ecological Services Office, 2321 W. Royal Palm Road, Suite 103, Phoenix, AZ 85021; telephone 602-242-0210; facsimile 602-242-2513.

FOR FURTHER INFORMATION CONTACT:

Steve Spangle, Field Supervisor, U.S. Fish and Wildlife Service, Arizona Ecological Services Office, 2321 W. Royal Palm Road, Suite 103, Phoenix, AZ 85021; telephone 602-242-0210; facsimile 602-242-2513. If you use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

In this final rule, we are changing the status of spikedace and loach minnow from threatened to endangered under the Act. We also are revising our designations of critical habitat for both species. We are under undertaking these actions pursuant to a settlement agreement and publication of this action will fulfill our obligations under that agreement. With the change in status for the species, the special rules for each species will be removed from the Code of Federal Regulations. In total, approximately 1,013 kilometers (630 miles) are designated as critical habitat for spikedace and 983 kilometers (610 miles) are designated as critical habitat for loach minnow in Apache, Cochise, Gila, Graham, Greenlee, Pinal, and Yavapai Counties, Arizona, and Catron, Grant, and Hidalgo Counties in New Mexico. Of this area, approximately 853 kilometers (529 miles) are designated for both species, with an additional 162 kilometers (100 miles) for spikedace only and an additional 130 kilometers (81 miles) for loach minnow only. We have excluded from this designation of critical habitat: portions of the upper San Pedro River in Arizona based on potential impacts to national security at Fort Huachuca; Tribal lands of the White Mountain Apache Tribe, San Carlos Apache Tribe, and the Yavapai-Apache Nation in Arizona; and private lands owned by Freeport-McMoRan in Arizona and New Mexico.

Background

It is our intent to discuss in this final rule only those topics directly relevant to the development and designations of critical habitat for the spikedace and the loach minnow under the Act (16 U.S.C. 1531

et seq.

). For more information on the biology and ecology of the spikedace and the loach minnow, refer to the final listing rule published in the

Federal Register

on July 1, 1986, for spikedace (51 FR 23769), and October 28, 1986, for loach minnow (51 FR 39468); the previous critical habitat designations (72 FR 13356, March 21, 2007); and our 1991 final recovery plans, which are available from the Arizona Ecological Services Office (see

ADDRESSES

section). For information on spikedace and loach minnow critical habitat, refer to the proposed rule to designate critical habitat for the two species published in the

Federal Register

on October 28, 2010 (75 FR 66482). A notice of availability regarding changes to the proposed rule and information on the associated draft economic analysis and draft environmental assessment for the proposed rule to designate revised critical habitat was published in the

Federal Register

on October 4, 2011 (76 FR 61330).

Previous Federal Actions

Previous Federal actions prior to October 28, 2010, are outlined in our proposed rule (75 FR 66482), which was published on that date. Publication of the proposed rule opened a 60-day comment period which closed on December 27, 2010. On October 4, 2011 (76 FR 61330), we published a revised proposed rule, announced the availability of a draft economic analysis and environmental assessment of the proposed designations, and announced the scheduling of a public information session and public hearing. Our October 4, 2011, notice also reopened the comment period on the revised proposed rule and uplisting for an additional 30 days, until November 3, 2011.

Spikedace

The spikedace is a member of the minnow family Cyprinidae, and is the only species in the genus

Meda.

The spikedace was first collected from the San Pedro River in 1851. The spikedace is a small, slim fish less than 75 millimeters (mm) (3 inches (in)) in length (Sublette

et al.

1990, p. 136). Spikedace have olive-gray to brownish skin, with silvery sides and vertically elongated black specks. Spikedace have spines in the dorsal fin (Minckley 1973, pp. 82, 112, 115).

Spikedace are found in moderate to large perennial streams, where they inhabit shallow riffles (those shallow portions of the stream with rougher, choppy water) with sand, gravel, and rubble substrates (Barber and Minckley 1966, p. 31; Propst

et al.

1986, p. 12; Rinne and Kroeger 1988, p. 1; Rinne 1991, pp. 8-10). Specific habitat for this species consists of shear zones where rapid flow borders slower flow; areas of sheet flow at the upper ends of midchannel sand or gravel bars; and eddies at downstream riffle edges (Rinne 1991, p. 11; Rinne and Kroeger 1988, pp. 1, 4). Recurrent flooding and a natural flow regime are very important in maintaining the habitat of spikedace and in helping maintain a competitive edge over invading nonnative aquatic species (Propst

et al.

1986, pp. 76-81; Minckley and Meffe 1987, pp. 97, 103-104).

The spikedace was once common throughout much of the Gila River basin, including the mainstem Gila River upstream of Phoenix, and the Verde, Agua Fria, Salt, San Pedro, and San Francisco subbasins. Habitat destruction and competition and predation by nonnative aquatic species reduced its range and abundance (Miller 1961, pp. 365, 377, 397-398; Lachner

et al.

1970, p. 22; Ono

et al.

1983, p. 90; Moyle 1986, pp. 28-34; Moyle

et al.

1986, pp. 416-423; Propst

et al.

1986, pp. 82-84). Spikedace are now restricted to portions of the upper Gila River (Grant, Catron, and Hidalgo Counties, New Mexico); Aravaipa Creek (Graham and Pinal Counties, Arizona);

Eagle Creek (Graham and Greenlee Counties, Arizona); and the Verde River (Yavapai County, Arizona) (Marsh

et al.

1990, pp. 107-108, 111; Brouder, 2002, pers. comm.; Stefferud and Reinthal 2005, pp. 16-21; Paroz

et al.

2006, pp. 62-67; Propst 2007, pp. 7-9, 11-14; Reinthal 2011, pp. 1-2).

In 2007, spikedace were translocated into Hot Springs and Redfield Canyons, in Cochise County, Arizona, and these streams were subsequently augmented (Robinson 2008a, pp. 2, 6; Robinson, 2008b, pers. comm.; Orabutt, 2009 pers. comm.; Robinson 2009a, pp. 2, 5-8). (We use the term “translocate” to describe stocking fish into an area where suitable habitat exists, but for which there are no documented collections.) Both Hot Springs and Redfield canyons are tributaries to the San Pedro River. Spikedace were also translocated into Fossil Creek, a tributary to the Verde River in Gila County, Arizona, in 2007, and were subsequently augmented in 2008 and 2011 (Carter 2007b, p. 1; Carter 2008a, p. 1; Robinson 2009b, p. 9; Boyarski

et al.

2010, p. 3, Robinson 2011a, p. 1). In 2008, spikedace were translocated into Bonita Creek, a tributary to the Gila River in Graham County, Arizona (Blasius, 2008, pers. comm.; Orabutt, 2009,, pers. comm.; Robinson

et al.

2009a, p. 209; Blasius and Conn 2011, p. 3), and were repatriated to the upper San Francisco River in Catron County, New Mexico (Propst, 2010, pers. comm.). (We use the term “repatriate” to describe stocking fish into an area where we have historical records of prior presence.) Augmentations with additional fish will occur for the next several years at all sites, if adequate numbers of fish are available. Monitoring at each of these sites is ongoing to determine if populations ultimately become self-sustaining.

The species is now common only in Aravaipa Creek in Arizona (AGFD 1994; Arizona State University (ASU) 2002; Reinthal 2011, pp. 1-2) and one section of the Gila River south of Cliff, New Mexico (NMDGF 2008; Propst

et al.

2009, pp. 14-17). The Verde River is presumed occupied; however, the last captured fish from this river was from a 1999 survey (Brouder 2002, p. 1; AGFD 2004). Spikedace from the Eagle Creek population have not been seen for over a decade (Marsh 1996, p. 2), although they are still thought to exist in numbers too low for the sampling efforts to detect (Carter

et al.

2007, p. 3; see Minckley and Marsh 2009). The Middle Fork Gila River population is thought to be very small and has not been seen since 1991 (Jakle 1992, p. 6), but sampling is localized and inadequate to detect a sparse population.

Population estimates have not been developed as a result of the difficulty in detecting the species, the sporadic nature of most surveys, and the difference in surveying techniques that have been applied over time. Based on the available maps and survey information, we estimate the present range for spikedace to be approximately 10 percent or less of its historical range, and the status of the species within occupied areas ranges from common to very rare. Data indicate that the population in New Mexico has declined in recent years (Paroz

et al.

2006, p. 56). Historical and current records for spikedace are summarized in three databases (ASU 2002, AGFD 2004, NMDGF 2008), which are referenced throughout this document.

Loach Minnow

The loach minnow is a member of the minnow family Cyprinidae. The loach minnow was first collected in 1851 from the San Pedro River in Arizona and was described by those specimens in 1856 by Girard (pp. 191-192). The loach minnow is a small, slender fish less than 80 mm (3 in) in length. It is olive-colored overall, with black mottling or splotches. Breeding males have vivid red to red-orange markings on the bases of fins and adjacent body, on the mouth and lower head, and often on the abdomen (Minckley 1973, p. 134; Sublette

et al.

1990, p. 186).

Loach minnow are found in small to large perennial streams and use shallow, turbulent riffles with primarily cobble substrate and swift currents (Minckley 1973, p. 134; Propst

et al.

1988, pp. 36-43; Rinne 1989, pp. 113-115; Propst and Bestgen 1991, pp. 29, 32-33). The loach minnow uses the spaces between, and in the lee (sheltered) side of, rocks for resting and spawning. It is rare or absent from habitats where fine sediments fill these interstitial spaces (Propst and Bestgen 1991, p. 34).

Loach minnow are now restricted to:

• Portions of the Gila River and its tributaries, the West, Middle, and East Fork Gila River (Grant, Catron, and Hidalgo Counties, New Mexico) (Paroz and Propst 2007, p. 16; Propst 2007, pp. 7-8, 10-11, 13-14);

• The San Francisco and Tularosa rivers and their tributaries, Negrito and Whitewater Creeks (Catron County, New Mexico) (Propst

et al.

1988, p. 15; ASU 2002; Paroz and Propst 2007, p. 16; Propst 2007, pp. 4-5);

• The Blue River and its tributaries, Dry Blue, Campbell Blue, Pace, and Frieborn Creeks (Greenlee County, Arizona, and Catron County, New Mexico) (Miller 1998, pp. 4-5; ASU 2002; Carter 2005, pp. 1-5; Carter, 2008b, pers. comm.; Clarkson

et al.

2008, pp. 3-4; Robinson 2009c, p. 3);

• Aravaipa Creek and its tributaries, Turkey and Deer Creeks (Graham and Pinal Counties, Arizona) (Stefferud and Reinthal 2005, pp. 16-21);

• Eagle Creek (Graham and Greenlee Counties, Arizona), (Knowles 1994, pp. 1-2, 5; Bagley and Marsh 1997, pp. 1-2; Marsh

et al.

2003, pp. 666-668; Carter

et al.

2007, p. 3; Bahm and Robinson 2009a, p. 1);

• The North Fork East Fork Black River (Apache and Greenlee Counties, Arizona) (Leon 1989, pp. 1-2; Lopez, 2000, pers. comm.; Gurtin, 2004, pers. comm.; Carter 2007b, p. 2; Robinson

et al.

2009b, p. 4); and

• Possibly the White River and its tributaries, the East and North Fork White River (Apache, Gila, and Navajo Counties, Arizona).

As described for spikedace above, population estimates for loach minnow have not been developed as a result of the difficulty in detecting the species, the sporadic nature of most surveys, and the difference in surveying techniques that have been applied over time. However, based on the available maps and survey information, we estimate the present range for loach minnow to be approximately 15 to 20 percent or less of its historical range, and the status of the species within occupied areas ranges from common to very rare. Data indicate that the population in New Mexico has declined in recent years (Paroz

et al.

2006, p. 56). Historical and current records for spikedace are summarized in three databases (ASU 2002, AGFD 2004, NMDGF 2008), which are referenced throughout this document.

Summary of Factors Affecting the Species

Under the Act and our implementing regulations, a species may warrant listing if it is endangered or threatened throughout all or a significant portion of its range. Both spikedace and loach minnow currently exist in a small portion of their historical range (10 percent, or less, for spikedace, and 15 to 20 percent for loach minnow), and the threats continue throughout its range. Accordingly, our assessment and determination applies to each species throughout its entire range. Section 4 of the Act (16 U.S.C. 1533), and implementing regulations (50 CFR part 424), set forth the procedures for adding species to the Federal Lists of Endangered and Threatened Wildlife and Plants.

Under section 4(a)(1) of the Act, a species may be determined to be endangered or threatened based on any of the following five factors: (1) The present or threatened destruction, modification, or curtailment of its habitat or range; (2) overutilization for commercial, recreational, scientific, or educational purposes; (3) disease or predation; (4) the inadequacy of existing regulatory mechanisms; or (5) other natural or manmade factors affecting its continued existence. In making this finding, information pertaining to spikedace and loach minnow, in relation to the five factors provided in section 4(a)(1) of the Act, is discussed below.

In considering what factors might constitute threats to a species, we must look beyond the exposure of the species to a factor to evaluate whether the species may respond to the factor in a way that causes actual impacts to the species. If there is exposure to a factor and the species responds negatively, the factor may be a threat and we attempt to determine how significant a threat it is. The threat is significant if it drives, or contributes to, the risk of extinction of the species such that the species warrants listing as endangered or threatened as those terms are defined in the Act.

Throughout the document, we discuss areas in which spikedace or loach minnow have been reintroduced, translocated, or augmented. For purposes of this document, we consider the species to have been reintroduced when they have been placed back into an area in which they were formerly present, but no longer are. We consider the fish to have been translocated when they are placed into a location for which we have no previous records of occurrence. Augmentation occurs when we add additional individuals to a former reintroduction or translocation project, in an attempt to establish a stable population.

A. The Present or Threatened Destruction, Modification, or Curtailment of Habitat or Range

Water Withdrawals

Water resources are limited in the Southwestern United States and diversions and withdrawals have led to the conversion of portions of habitat to intermittent streams or reservoirs unsuitable for spikedace or loach minnow. Growing water demands reduce southern Arizona perennial surface water and threaten aquatic species. Historically, water withdrawals led to the conversion of large portions of flowing streams into intermittent streams, large reservoirs, or dewatered channels, thus eliminating suitable spikedace and loach minnow habitat in impacted areas (Propst

et al.

1986, p. 3; Tellman

et al.

1997, pp. 37, 50, 63-64, 66, 103). These habitat changes, together with the introduction of nonnative fish species (see factors C and E), have resulted in the extirpation of spikedace and loach minnow throughout an estimated 80 to 90 percent of their historical ranges.

Spikedace and loach minnow are stream-dwelling fish, and are associated only with flowing water. Spikedace are found in moderate to large perennial streams, and occur where the stream has flowing, rougher, choppy water (Barber and Minckley 1966, p. 31; Propst

et al.

1986, p. 12; Rinne and Kroeger 1988, p. 1; Rinne 1991, pp. 8-10). Loach minnow occur in shallow, turbulent riffles where there are swift currents (Minckley 1973, p. 134; Propst

et al.

1988, pp. 36-43; Rinne 1989, pp. 113-115; Propst and Bestgen 1991, pp. 29, 32-33). Water withdrawals that either dewater channels or reduce flows to low levels or pools within an active channel therefore eliminate the habitat used by the two species.

Many streams currently or formerly occupied by spikedace and loach minnow have been affected by water withdrawals. The Gila River downstream of the town of Cliff, New Mexico, flows through a broad valley where irrigated agriculture and livestock grazing are the predominant uses. Human settlement has increased since 1988 (Propst

et al.

2008 (pp. 1237-1238). Agricultural practices have led to dewatering of the river in the Cliff-Gila valley at times during the dry season (Soles 2003, p. 71). For those portions of the Gila River downstream of the Arizona-New Mexico border, agricultural diversions and groundwater pumping have caused declines in the water table, and surface flows in the central portion of the river basin are diverted for agriculture (Leopold 1997, pp. 63-64; Tellman

et al.

1997, pp. 101-104; Arizona Department of Water Resources 2000, pp. 16-17).

The San Francisco River has undergone sedimentation, riparian habitat degradation, and extensive water diversion and at present has an undependable water supply throughout portions of its length. The San Francisco River is seasonally dry in the Alma Valley, and two diversion structures fragment habitat in the upper Alma Valley and at Pleasanton (NMDGF 2006, p. 302). The San Francisco River in Arizona was classified as impaired due to excessive sediment from its headwaters downstream to the Arizona—New Mexico border (Arizona Department of Water Resources 2011a, p. 1).

Additional withdrawals of water from the Gila and San Francisco rivers may occur in the future. Implementation of Title II of the Arizona Water Settlements Act (AWSA) (Pub. L. 108-451) would facilitate the exchange of Central Arizona Project water within and between southwestern river basins in Arizona and New Mexico, and may result in the construction of new water development projects. For example, Section 212 of the AWSA pertains to the New Mexico Unit of the Central Arizona Project.

The AWSA provides for New Mexico water users to deplete 140,000 acre-feet of additional water from the Gila Basin in any ten-year period. The settlement also provides the ability to divert that water without complaint from downstream pre-1968 water rights in Arizona. New Mexico will receive $66 million to $128 million in non-reimbursable federal funding. The Interstate Stream Commission (ISC) funds may be used to cover costs of an actual water supply project, planning, environmental mitigation, or restoration activities associated with or necessary for the project, and may be used on one or more of 21 alternative projects ranging from Gila National Forest San Francisco River Diversion/Ditch improvements to a regional water supply project (the Deming Diversion Project). At this time, it is not known how the funds will be spent, or which potential alternative(s) may be chosen.

While multiple potential project proposals have been accepted by the New Mexico Office of the State Engineer (NMOSE) (NMOSE 2011a, p. 1), implementation of the AWSA is still in the planning stages on these streams. The AWSA mandates that the ISC make the final determination of contracts for water and allocation of funding and provide notice to the Secretary of the Interior by December 31, 2014. New Mexico ISC must make any final determination during an open, public meeting, and only after consultation with the Gila San Francisco Water Commission, the citizens of Southwest New Mexico, and other affected interests. Due to the timeline associated with this project, as well as the uncertainties in how funding will be spent, and which potential alternative or alternatives will be chosen, the Service is unable to determine the outcome of this process at this time. However, should water be diverted from the Gila or San Francisco rivers, flows would be diminished and direct and indirect losses and degradation of

habitat for aquatic and riparian species would result. The San Francisco River is currently occupied by loach minnow, and is the site of a 2008 reintroduction for spikedace. The Gila River is a stronghold for both species, currently supporting the largest remaining populations of each. For these reasons, impacts to either river is of particular concern for the persistence of these species.

Groundwater withdrawal in Eagle Creek, primarily for water supply for a large open-pit copper mine at Morenci, Arizona dries portions of the stream (Sublette

et al.

1990, p. 19; Service 2005; Propst

et al.

1986, p. 7). Mining is the largest industrial water user in southeastern Arizona. The Morenci mine on Eagle Creek is North America's largest producer of copper, covering approximately 24,281 hectares (ha) (60,000 acres (ac)). Water for the mine is imported from the Black River, diverted from Eagle Creek as surface flows, or withdrawn from the Upper Eagle Creek Well Field (Arizona Department of Water Resources 2009, p.  1).

Aravaipa Creek is relatively protected from further instream habitat loss due to water withdrawals because it is partially within a Bureau of Land Management (BLM) Wilderness area and partially within a Nature Conservancy preserve. However, Aravaipa Creek is affected by upstream uses in the watershed, primarily groundwater pumping for irrigation. Irrigation can reduce creek flows, as crop irrigation uses large amounts of water, especially during the summer months when the creek flows are already at their lowest. Increased groundwater pumping from wells is known to be linked to reduced creek flows (JE Fuller 2000, pp. 4-8).

On the mainstem Salt River, impoundments have permanently limited the flow regime and suitability for spikedace or loach minnow. Spikedace are extirpated from portions of the Salt and Gila Rivers that were once perennial and are now classified as regulated (ASU 2002, The Nature Conservancy 2006).

Water depletion is also a concern for the Verde River. In 2000, the Arizona Department of Water Resources (2000, p. 1-1) reported that the populations of major cities and towns within the Verde River watershed had more than doubled in the last 20 years, resulting in more than a 39 percent increase in municipal water usage. The Arizona Department of Water Resources (2000, p. 1-1) anticipated that human populations in the Verde River watershed are expected to double again before 2040, resulting in more than a 400 percent increase over the 2000 water usage. The middle and lower Verde River has limited or no flow during portions of the year due to agricultural diversion and upstream impoundments, and has several impoundments in its middle reaches, which could expand the area of impacted spikedace and loach minnow habitat. The Little Chino basin within the Verde River watershed has already experienced significant groundwater declines that have reduced flow in Del Rio Springs (Arizona Department of Water Resources 2000, pp. 1-1, 1-2). Blasch

et al.

(2006, p. 2) suggests that groundwater storage in the Verde River watershed has already declined due to groundwater pumping and reductions in natural channel recharge resulting from streamflow diversions.

Also impacting water in the Verde River, the City of Prescott, Arizona, experienced a 22 percent increase in population between 2000 and 2005 (U.S. Census Bureau 2010, p. 1), averaging around 4 percent growth per year (City of Prescott 2010, p. 1). In addition, the towns of Prescott Valley and Chino Valley experienced growth rates of 66 and 67 percent, respectively (Arizona Department of Commerce 2009a, p. 1; 2009b, p. 1). This growth is facilitated by groundwater pumping in the Verde River basin. In 2004, the cities of Prescott and Prescott Valley purchased a ranch in the Big Chino basin in the headwaters of the Verde River, with the intent of drilling new wells to supply up to approximately 4,933,927 cubic meters (4,000 acre-feet (AF)) of groundwater per year. If such drilling occurs, it could have serious adverse effects on the mainstem and tributaries of the Verde River.

Scientific studies have shown a link between the Big Chino aquifer and spring flows that form the headwaters of the Verde River. It is estimated that 80 to 86 percent of baseflow in the upper Verde River comes from the Big Chino aquifer (Wirt 2005, p. G8). However, while these withdrawals could potentially dewater the upper 42 km (26 mi) of the Verde River (Wirt and Hjalmarson 2000, p. 4), it is uncertain that this project will occur given the legal and administrative challenges it faces; however, an agreement in principle was signed between various factions associated with water rights and interests on the Verde River (Citizens Water Advocacy Group 2010; Verde Independent 2010, p. 1).

This upper portion of the Verde River is considered currently occupied by spikedace, and barrier construction and stream renovation plans are under way with the intention of using this historically occupied area for recovery of native fishes including loach minnow. Reductions of available water within this reach could preclude its use for recovery purposes. This area is currently considered occupied by spikedace that are considered genetically (Tibbets 1993, pp. 25-29) and morphologically (Anderson and Hendrickson 1994, pp. 148, 150-154) distinct from all other spikedace populations.

Portions of the San Pedro River are now classified as formerly perennial, including areas from which spikedace and loach minnow are now extirpated (The Nature Conservancy 2006). Water withdrawals are also a concern for the San Pedro River. The Cananea Mine in Sonora, Mexico, owns the land surrounding the headwaters of the San Pedro. There is disagreement on the exact amount of water withdrawn by the mine, Mexicana de Cananea, which is one of the largest open-pit copper mines in the world. However, there is agreement that it is the largest water user in the basin (Harris

et al.

2001; Varady

et al.

2000, p. 232).

Another primary groundwater user in the San Pedro watershed is Fort Huachuca. Fort Huachuca is a U.S. Army installation located near Sierra Vista, Arizona. Initially established in 1877 as a camp for the military, the water rights of the Fort are predated only by those of local Indian tribes (Varady

et al.

2000, p. 230). Fort Huachuca has pursued a rigorous water use reduction plan, working over the past decade to reduce groundwater consumption in the Sierra Vista Subwatershed. Their efforts have focused primarily on reductions in groundwater demand both on-post and off-post and increased artificial and enhanced recharge of the groundwater system. Annual pumping from Fort Huachuca production wells has decreased from a high of approximately 3,200 AF in 1989 to a low of approximately 1,400 AF in 2005. In addition, Fort Huachuca and the City of Sierra Vista have increased the amount of water recharged to the regional aquifer through construction of effluent recharge facilities and detention basins that not only increase stormwater recharge but mitigate the negative effects of increased runoff from urbanization. The amount of effluent that was recharged by Fort Huachuca and the City of Sierra Vista in 2005 was 426 AF and 1,868 AF, respectively. During this same year, enhanced stormwater recharge at detention basins was estimated to be 129 AF. The total net effect of all the combined efforts initiated by Fort Huachuca has been to reduce the net groundwater

consumption by approximately 2,272 AF (71 percent) since 1989 (Service 2007, pp. 41-42).

In addition to impacts on water availability within streams, diversion structures can create barriers for fish movement. Larger dams may prevent movement of fish between populations and dramatically alter the flow regime of streams through the impoundment of water (Ligon

et al.

1995, pp. 184-189). These diversions also require periodic maintenance and reconstruction, resulting in potential habitat damages and inputs of sediment into the active stream.

In summary, water withdrawals have occurred historically, and continue to occur, throughout the ranges of spikedace and loach minnow. Groundwater pumping and surface diversions used for agricultural, industrial, and municipal purposes can lead to declines in the water table and dewatering of active stream channels. Ongoing water withdrawals are known to occur on the Gila, San Francisco, and Verde rivers, and are occurring at limited levels, with the potential for increased withdrawals on Aravaipa Creek.

Stream Channel Alteration

Sections of many Gila Basin rivers and streams have been, and continue to be, channelized for flood control, which disrupts natural channel dynamics (sediment scouring and deposition) and promotes the loss of riparian plant communities. Channelization changes the stream gradient above and below the channelization. Water velocity increases in the channelized section, which results in increased rates of erosion of the stream and its tributaries, accompanied by gradual deposits of sediment in downstream reaches that may increase the risk of flooding (Emerson 1971, p. 326; Simpson 1982, p. 122). Historical and ongoing channelization will continue to contribute to riparian and aquatic habitat decline most notably eliminating cover and reducing nutrient input.

Stream channel alteration can affect spikedace and loach minnow habitat by reducing its complexity, eliminating cover, reducing nutrient input, improving habitat for nonnative species, changing sediment transport, altering substrate size, increasing flow velocities, and reducing the length of the stream (and therefore the amount of aquatic habitat available) (Gorman and Karr 1978, pp. 512-513; Simpson 1982, p. 122; Schmetterling

et al.

2001, pp. 7-10). Loach minnow occupy interstitial spaces between cobble (Propst and Bestgen 1991, p. 34), and increases in sedimentation can fill these spaces in, removing shelter for loach minnow, and reducing available breeding habitat. Spikedace are typically found over sand, gravel, and rubble substrates (Barber and Minckley 1966, p. 31; Propst

et al.

1986, p. 12; Rinne and Kroeger 1988, p. 1; Rinne 1991, pp. 8-10). Changes in sediment transport and alteration of substrate size can make an area unsuitable for spikedace. Both species occur in streams with specific water velocities, and increasing flow velocities as a result of channelization may also make an area unsuitable.

Water Quality

In the past, the threat from water pollution was due primarily to catastrophic pollution events (Rathbun 1969, pp. 1-5; Eberhardt 1981, pp. 3-6, 8-10) or chronic leakage from large mining operations (Eberhardt 1981, pp. 2, 16). Although this is not as large a problem today as it was historically, some damage to spikedace and loach minnow populations still occurs from occasional spills or chronic inability to meet water quality standards (

United States

v.

ASARCO,

No. 98-0137 PHX- ROS (D. Ariz. June 2, 1998)). Mine tailings from a number of past and present facilities throughout the Gila Basin would threaten spikedace populations if catastrophic spills occur (Arizona Department of Health Services 2010, p. 3). Spills or discharges have occurred in the Gila River and affected streams within the watersheds of spikedace and loach minnow, including the Gila River, San Francisco River, San Pedro River, and some of their tributaries (Environmental Protection Agency (EPA) 1997, pp. 24-67; Arizona Department of Environmental Quality 2000, p. 6; Church

et al.

2005, p. 40; Arizona Department of Environmental Quality 2007, p. 1).

In January of 2006, the Arizona Department of Environmental Quality announced that it had been conducting a remedial investigation at the Klondyke tailings site on Aravaipa Creek, which currently supports one of the two remaining populations where spikedace and loach minnow are considered common. The Klondyke tailings site was a mill that processed ore to recover lead, zinc, copper, silver, and gold between the 1920s and the 1970s. There are eight contaminants in the tailings and soil at the Klondyke tailings site that are at levels above regulatory limits. These contaminants are: antimony; arsenic; beryllium; cadmium; copper; lead; manganese; and zinc. Samples of shallow groundwater collected at the site contained arsenic, beryllium, cadmium, chromium, lead, and nickel above regulatory limits (Arizona Department of Environmental Quality 2006, p. 2; Arizona Department of Water Resources 2011b, p. 1). A preliminary study in Aravaipa Creek has found high levels of lead in two other native fish species, Sonora sucker (

Catostomus insignis

) and roundtail chub (

Gila robusta

), as well as in the sediment and in some of the invertebrates. These lead levels are high enough that they could negatively impact reproduction (Reinthal, 2010, pers. comm.). We do not know with certainty whether these levels of lead would affect spikedace or loach minnow, but we assume similar impacts would occur as they are collocated with Sonora sucker and roundtail chub in Aravaipa Creek.

The Service completed contaminant studies on the San Francisco River and Gila River in the 1990s. Two sites on the San Francisco River exceeded the International Joint Commission (IJC) background level standards for arsenic, cadmium, copper, mercury, and zinc. Cadmium levels at site 2 were approximately 16.5 times the background level, while copper was nearly 25 times greater than the background level. The two San Francisco River sites did not exceed domestic water source water quality standards for trace element concentrations, where those standards are provided for Arizona. The study site closest to, but downstream of, the portion of the Gila River included in the designation exceeded IJC background level standards for trace element concentrations for arsenic, cadmium, and copper. DDE was recovered in all whole body and edible fish samples, as were aluminum, arsenic, barium, chromium, selenium, and strontium. Cadmium, mercury, and selenium concentrations were determined to potentially pose a threat to fish-eating birds in the Gila River basin (Baker and King 1994, pp. 6-14, 17, 19, 22).

Organochlorine contaminants detected included heptachlor, chlordane, and DDE. The concentrations of these pesticides were below concentrations known to affect survival and reproduction of most fish species.

The study recommended continued monitoring, due to the high cadmium and mercury concentrations that approach the critical reproductive effect threshold level in more than one-half of the samples. In addition, the study recommended monitoring for selenium as selenium levels exceeded dietary levels for protection of avian predators. Such monitoring has not occurred.

The Arizona Department of Water Resources notes that 67 sites on the San Pedro River have parameter

concentrations that have equaled or exceeded their drinking water standards. The most frequently equaled or exceeded parameters included arsenic and fluoride, but other parameters equaled or exceeded in the sites measured in the San Pedro Basin were cadmium, lead, nitrates, beryllium, mercury, and total dissolved solids (Arizona Department of Water Resources 2011c, p. 1). The Verde River has three different reaches that exceed standards for turbidity, totaling 37.5 miles between Oak Creek and West Clear Creek. Additionally, Oak Creek exceeds the standards for

E. coli

(Arizona Department of Water Resources 2011d, p. 1).

There are few studies, with the exception of the study at Aravaipa Creek, which discuss contaminants on spikedace and loach minnow. Generally, contaminants can have both sublethal and lethal effects. Sublethal effects are those, such as the lead contamination at Aravaipa Creek, which may reduce a species' ability to reproduce. Lethal are those effects that result in death for the species. Large fish kills are more rare now than in the past.

Pollution is increasingly more widespread and more often from nonpoint sources. Urban and suburban development is one source of nonpoint-source pollution. Increasing the amount of runoff from roads, golf courses, and other sources of petroleum products, pesticides, and other toxic materials can cause changes in fish communities (Wang

et al.

1997, pp. 6, 9, 11). Nutrient and sediment loads are increasing in urban areas (King

et al.

1997, pp. 7-24, 38, 39) and, combined with depleted stream flows, can be serious threats to aquatic ecosystems during some periods of the year. Sewage effluent can contain lead, especially where the treatment plant receives industrial discharges or highway runoff (Hoffman

et al.

1995, p. 361). The number of bridges and roads increases with expanding rural and urban populations in Arizona (Arizona Department of Transportation 2000, pp. 1-3), and pose significant risks to the fish from increases in toxic materials along roadways (Trombulak and Frissell 2000, pp. 22-24). Some metals, like lead and cadmium, are associated with fuel combustion. Lead can be found in vehicle emissions (Hoffman

et al.

1995, pp. 369, 405).

As noted previously, human populations within the ranges of spikedace and loach minnow are expected to increase over the next 20 years. Therefore, we expect a corresponding increase in nonpoint-source pollution.

Exposure to pesticides can result in a variety of behaviors. Sublethal behaviors are those that do not result in death. Sublethal responses of fish to pesticide exposure can include central nervous system disorders, increased ventilation rates, loss of equilibrium, rapid, jerky movements, dark discoloration or hemorrhaging in muscles and beneath the dorsal fin, erratic, uncoordinated swimming movements with spasms and convulsions, and spinal abnormalities (Meyer and Barclay 1990, p. 21).

Exposure to metals at toxic levels can have varying effects. Low levels of some metals, such as selenium, are essential for good health. However, excess levels of selenium can be toxic, and selenium is considered one of the most toxic elements to fish (Sorensen 1991, pp. 17-22). For other metals such as lead, all known effects on biological systems are negative (Hoffman

et al.

1995, p. 356).

Exposure to metals causes a variety of impacts, including disruption to feeding behaviors, altered respiratory rates, growth inhibition, and delayed sexual maturation; damage to body structure including skin, nervous system, and musculature, gills, fins, and spines; damage to organs including the liver, kidneys, intestines, heart, and chemoreceptors (used in migration); alterations to blood and blood chemistry, including red blood cells, hemoglobin levels, protein concentrations, glucose concentrations, and antibody titers; and damage to the nervous system leading to muscle spasms, paralysis, hyperactivity, and a loss of equilibrium (Sorensen 1991, pp. 17-22, 34-48 (selenium), 74-78 (arsenic); 104-107 (lead); 153-164 (zinc); 199-219 (cadmium); 253-275 (copper); and 312-323 (mercury)).

The impacts of a toxin in a system vary by species, as well as by age level of the organism. For some metals, such as copper or mercury, fish are more severely affected at the embryonic and reproductive stages of the life cycle (Sorensen 1991, p. 269; Hoffman

et al.

1995, p. 398). It is also important to note that, for some metals, such as cadmium, copper, lead, and mercury, increased temperatures or changes in water chemistry, such as pH or organic matter, can affect the toxicity of the metal (Sorensen 1991, p. 184; Hoffman

et al.

1995, pp. 395-396). Therefore, there can be an increased threat from exposure to toxins in streams that have also undergone alterations such as vegetation removal due to fire or construction and maintenance activities, or improper livestock grazing.

An additional, increasing source of contamination for streams is caused by wildfires and their suppression. Based on historical records and long term tree-ring records, wildfires have increased in the ponderosa pine forests of the Southwest, including the range of the spikedace and loach minnow (Swetnam and Betancourt 1990, pp. 1017, 1019; Swetnam and Betancourt 1998, pp. 3131-3135). This is due to a combination of decades of fire suppression, increases in biomass due to increased precipitation after 1976, and warming temperatures coupled with recent drought conditions (University of Arizona 2006, pp. 1, 3). As wildfires increase, so does the use of fire-retardant chemical applications. Some fire-retardant chemicals are ammonia-based, which is toxic to aquatic wildlife; however, many formulations also contain yellow prussiate of soda (sodium ferrocyanide), which is added as an anticorrosive agent. Such formulations are toxic for fish, aquatic invertebrates, and algae (Angeler

et al.

2006, pp. 171-172; Calfee and Little 2003, pp. 1527-1530; Little and Calfee 2002, p. 5; Buhl and Hamilton 1998, p. 1598; Hamilton

et al.

1998, p. 3; Gaikwokski

et al.

1996, pp. 1372-1373). Toxicity of these formulations is enhanced by sunlight (Calfee and Little 2003, pp. 1529-1533).

In a 2008 biological opinion issued by the Service to the U.S. Forest Service (USFS) on the nationwide use of fire retardants, the Service concluded that the use of fire retardants can cause mortality to fish by exposing them to ammonia. We concluded in the opinion that the proposed action, which included the application of fire retardants throughout the range of the species, was likely to jeopardize the continued existence of the spikedace and loach minnow (Service 2008a). This consultation was recently reinitiated and completed in October 2011. The revised biological opinion included additional buffers and protective measures and concluded that the revised protocol for fire retardant use was not likely to jeopardize the continued existence of either spikedace or loach minnow (Service 2011).

Severe wildfires capable of extirpating or decimating fish populations are a relatively recent phenomenon, and result from the cumulative effects of historical or ongoing grazing and fire suppression (Madany and West 1983, pp. 665-667; Savage and Swetnam 1990, p. 2374; Swetnam 1990, p. 12; Touchan

et al.

1995, pp. 268-271; Swetnam and Baisan 1996, p. 29; Belsky and Blumenthal 1997, pp. 315-316, 324-325; Gresswell 1999, pp. 193-194, 213). Historical wildfires were primarily cool-burning understory fires with

return intervals of 4 to 8 years in ponderosa pine (Swetnam and Dieterich 1985, pp. 390, 395). Cooper (1960, p. 137) concluded that, prior to the 1950s, crown fires were extremely rare or nonexistent in the region. However, since 1989, high-severity wildfires, and subsequent floods and ash flows, have caused the extirpation of several populations of Gila trout in the Gila National Forest, New Mexico (Propst

et al.

1992, pp. 119-120, 123; Brown

et al.

2001, pp. 140-141). It is not known if spikedace or loach minnow have suffered local extirpations; however, native fishes, including spikedace and loach minnow, in the West Fork Gila River, showed 60 to 80 percent decreases in population following the Cub Fire in 2002, due to flooding events after the fire (Rinne and Carter 2008, pp. 171). Increased fines (sediments) and ash may be continuing to affect the populations on the West Fork Gila, near the Gila Cliff Dwellings (Propst

et al.

2008, p. 1247).

Since the proposed rule was published in October of 2011, the Wallow Fire burned portions of the critical habitat designations for spikedace and loach minnow, specifically the Black River Complex in Unit 2 (loach minnow only), and the Blue River Complex in Unit 7 (both species). The Wallow Fire encompassed just over 217,721 ha (538,000 ac) total in Arizona and New Mexico (InciWeb 2011), and was the largest wildfire in Arizona's history.

Portions of Units 2 and 7 of the critical habitat designation fall within the Wallow Fire perimeter. Within Unit 2, the North Fork East Fork Black River falls within an unburned area inside the perimeter of the fire, as does most of Boneyard Creek. The majority of East Fork Black River falls within an area that experienced low burn severity, but does cross a few areas that were either unburned or burned at moderate burn severity. Coyote Creek is in an area almost entirely burned at low severity. Within Unit 7, the majority of Campbell Blue Creek is within unburned or low burn severity areas; however, approximately 2.4 km (1.5 mi) of the upper end of Campbell Blue Creek is within moderate and high burn severity. The Wallow Fire stopped just west of the Blue River, but came within approximately 0.3 km (0.2 mi) of the River. However, the rainfall during the summer monsoon, which began before the fire was extinguished, contributed ash and sediment to both streams. In the Blue River, ash and sediment travelled as far downstream as the San Francisco River, resulting in fish kills (Blasius, 2011, pers. comm.). Fish surveys completed in the fall of 2011 indicated reduced numbers of loach minnow (Adelsberger

et al.

2011, p. 1).

Effects of fire may be direct and immediate or indirect and sustained over time. Because spikedace and loach minnow are found primarily in the lower elevation, higher-order streams, they are most likely affected by the indirect effects of fire (e.g., ash flows, increased water temperatures), not direct effects (e.g., drastic changes in pH, ammonium concentrations). Indirect effects of fire include ash and debris flows, increases in water temperature, increased nutrient inputs, and sedimentation, some of which can last for several years to more than a decade after the fire (Amaranthus

et al.

1989, pp. 75-77; Propst

et al.

1992, pp. 119-120; Gresswell 1999, pp. 194-211; Burton 2005, pp. 145-146; Dunham

et al.

2007, pp. 335, 340-342; Rinne and Carter 2008, pp. 169-171; Mahlum

et al.

2011, pp. 243-246). Of these, ash flows probably have the greatest effect on spikedace and loach minnow. Ash and debris flows may occur months after fires, when barren soils are eroded during monsoonal rain storms (Bozek and Young 1994, pp. 92-94). Ash and fine particulate matter created by fire can fill the interstitial spaces between gravel particles, eliminating spawning habitat or, depending on the timing, suffocating eggs that are in the gravel. Ash and debris flows can also decimate aquatic invertebrate populations that the fish depend on for food (Molles 1985, p. 281).

Recreation

The impacts to spikedace and loach minnow from recreation can include movement of people or livestock, such as horses or mules, along streambanks, trampling, loss of vegetation, and increased danger of fire (Northern Arizona University 2005, p. 136; Monz

et al.

2010, pp. 553-554). In the arid Gila River Basin, recreational impacts are disproportionately distributed along streams as a primary focus for recreation (Briggs 1996, p. 36). Within the range of spikedace and loach minnow, the majority of the occupied areas occur on Federal lands, which are managed for recreation and other purposes. Spikedace and loach minnow are experiencing increasing habitat impacts from such use in some areas. For example, Fossil Creek experienced an increase in trail use at one site, with an estimated 8,606 hikers using the trail in 1998, and an estimated 19,650 hikers using the trail in 2003. Dispersed camping also occurs in the area. The greatest impacts from camping were vegetation loss and litter (Northern Arizona University 2005, pp. 134-136). Similar impacts have been observed at Aravaipa Creek. We do not have information on the impacts of litter on spikedace and loach minnow; however, impacts from vegetation loss can include soil compaction, which when combined with vegetation loss, can result in increased runoff and sedimentation in waterways (Monz

et al.

2010, pp. 551-553; Andereck 1993, p. 2).

Recreation overuse can result in decreased riparian vegetation (USFS 2008, pp. 7-17) and subsequent increases in stream temperatures. Recreation is cited as one of the causes of impairment due to water temperature on the West Fork Gila River (EPA 2010, p. 1). We discuss temperature tolerances below in the microhabitat discussions for each species. Spikedace and loach minnow are known to have a range of temperatures in which they occur, and recent research by the University of Arizona has determined upper temperature tolerances for the two species. Spikedace did not survive exposure of 30 days at 34 or 36 °C (93.2 or 96.8 °F), and 50 percent mortality occurred after 30 days at 32.1 °C (89.8 °F). In addition, growth rate was slowed at 32 °C (89.6 °F), as well as at the lower test temperatures of 10 and 4 °C (50 and 39.2 °F). Multiple behavioral and physiological changes were observed, indicating the fish became stressed at 30, 32, and 33 °C (86, 89.6 and 91.4 °F) treatments. Similarly, the study determined that no loach minnow survived for 30 days at 32 °C (89.6 °F), and that 50 percent mortality occurred after 30 days at 30.6 °C (87.1 °F). For loach minnow, growth rate slowed at 28 and 30 °C (82.4 and 86.0 °F) compared to growth at 25 °C (77 °F), indicating that loach minnow were stressed at sublethal temperatures. The study concludes that temperature tolerance in the wild may be even lower due to the influence of additional stressors, including disease, predation, competition, or poor water quality.

Roads and Bridges

Roads impact Gila River Basin streams (Dobyns 1981, pp. 120-129, 167, 198-201), including spikedace, loach minnow, and their habitats (Jones

et al.

2000, pp. 82-83). The need for bridges and roads increases with increasing rural and urban populations in Arizona (Arizona Department of Transportation 2000, pp. 1-3). In addition, existing roads and bridges have ongoing maintenance requirements that result in alterations of stream channels within spikedace and loach minnow habitats (Service 1994a, pp. 8-

12; Service 1995a, pp. 10-12; Service 1995b, pp. 5-7; Service 1997a, pp. 10-15; Service 1997b, pp. 54-77). Bridge construction or repair causes channel alteration and, if not carefully executed, can result in long-term channel adjustments, altering habitats upstream and downstream. In some areas, low-water crossings exist within occupied spikedace and loach minnow habitats and cause channel modification and habitat disruption. Low-water crossings on general-use roads exist in a number of areas that may support spikedace and loach minnow. These crossings frequently require maintenance following minor flooding.

Generally, there are fewer new bridge construction projects within critical habitat; however, one proposed bridge will occur near the designation for spikedace in Unit 2 over Tonto Creek. Road and bridge maintenance and repairs occur frequently on the Blue River. There have been repeated road repairs near the Gila Cliff Dwellings on the West Fork Gila River because the bridge span is too short to accommodate peak flows. This is a common problem on bridges that cross the Gila River, and on other rivers occupied by spikedace and loach minnow in the Southwest. In an attempt to protect bridges, large amounts of fill (such as boulders, rip rap, and dirt) are used to confine and redirect the river. Typically, this habitat alteration is detrimental to spikedace and loach minnow because it changes the channel gradient and substrate composition, and reduces habitat availability. Eventually, peak flows remove the fill material, roads and bridges are damaged, and the resulting repairs and reconstruction lead to additional habitat disturbance (Service 1998, 2002a, 2005, 2008b, 2008c, 2009, 2010a).

The impacts of bridge and road construction, usage, and repairs can include increased sedimentation, either due to driving across low-water crossings in active stream channels, or due to excavation associated with maintenance and repair activities. Vehicles using low-water crossings as well as heavy equipment in active channels during construction or repairs can both harm eggs of spikedace and loach minnow, and compress substrates so that the interstitial spaces used by adult loach minnow are removed. Maintenance and construction work on banks around bridges and roads may also lead to increased sedimentation due to sediment disturbance or the removal of vegetation.

Livestock Grazing

Livestock grazing has been one of the most widespread and long-term causes of adverse impacts to native fishes and their habitat (Miller 1961, pp. 394-395, 399), but is one of the few threats where adverse effects to species such as spikedace and loach minnow are decreasing, due to improved management on Federal lands (Service 1997c, pp. 121-129, 137-141; Service 2001, pp. 50-67). This improvement occurred primarily by discontinuing grazing in the riparian and stream corridors. However, although adverse effects are less than in the past, livestock grazing within watersheds where spikedace and loach minnow and their habitats are located continues to cause adverse effects. These adverse effects occur through watershed alteration and subsequent changes in the natural flow regime, sediment production, and stream channel morphology (Platts 1990, pp. I-9—I-11; Belsky

et al.

1999, pp. 1-3, 8-10; Service 2001, pp. 50-67).

Livestock grazing can destabilize stream channels and disturb riparian ecosystem functions (Platts 1990, pp. I-9—I-11; Armour

et al.

1991, pp. 7-10; Tellman

et al.

1997, pp. 20-21, 33, 47, 101-102; Wyman

et al.

2006, pp. 5-7). Medina

et al.

(2005, p. 99) note that the impacts of grazing vary within and among ecoregions, and that some riparian areas can sustain little to no ungulate grazing, while others can sustain very high use. They further note that threatened and endangered fish populations and their associated riparian habitat “* * * may require some form of protection from grazing of all ungulates (e.g., elk, deer, cattle) * * *”. Improper livestock grazing can negatively affect spikedace and loach minnow through removal of riparian vegetation (Propst

et al.

1986, p. 3; Clary and Webster 1989, p. 1; Clary and Medin 1990, p. 1; Schulz and Leininger 1990, p. 295; Fleishner 1994, pp. 631-633, 635-636), that can result in reduced bank stability and higher water temperatures (Kauffman and Krueger 1984, pp. 432-434; Platts and Nelson 1989, pp. 453, 455; Fleishner 1994, pp. 635-636; Belsky

et al.

1999, pp. 2-5, 9-10). Livestock grazing can also cause increased sediment in the stream channel, due to streambank trampling and riparian vegetation loss (Weltz and Wood 1986, pp. 364-368; Pearce

et al.

1998, pp. 302, 307; Belsky

et al.

1999, p. 10). Livestock can physically alter the streambank through trampling and shearing, leading to bank erosion (Trimble and Mendel 1995, pp. 243-244; Belsky

et al.

1999, p. 1). In combination, loss of riparian vegetation and bank erosion can alter channel morphology, including increased erosion and deposition, increased sediment loads, downcutting, and an increased width-to-depth ratio, all of which lead to a loss of spikedace and loach minnow habitat components. Livestock grazing management also continues to include construction and maintenance of open stock tanks, which are often stocked with nonnative aquatic species harmful to spikedace and loach minnow (Service 1997b, pp. 54-77) if they escape or are transported to waters where these native fish occur.

An indirect effect of grazing can include the development of water tanks for livestock. In some cases, stocktanks are used to stock nonnative fish for sportfishing, or they may support other nonnative aquatic species such as bullfrogs or crayfish. In cases where stocktanks are in close proximity to live streams, they may occasionally be breached or flooded, with nonnative fish escaping from the stocktank and entering stream habitats (Hedwall and Sponholtz 2005, pp. 1-2; Stone

et al.

2007, p. 133).

Climate Conditions

Climate conditions have contributed to the status of the spikedace and loach minnow now and will likely continue into the future. While floods may benefit the species, habitat drying affects the occurrence of natural events, such as fire, drought, and forest die-off, and increases the chances of disease and infection.

Consideration of climate change is a component of our analyses under the Endangered Species Act. In general terms, “climate change” refers to a change in the state of the climate (whether due to natural variability, human activity, or both) that can be identified by changes in the mean or variability of its properties, and that persists for an extended period—typically decades or longer (Intergovernmental Panel on Climate Change (IPCC) 2007a, p. 78).

Changes in climate are occurring. Examples include warming of the global climate system over recent decades, and substantial increases in precipitation in some regions of the world and decreases in other regions (for these and other examples see IPCC 2007a, p. 30; Solomon

et al.

2007, pp. 35-54, 82-85).

Most of the observed increase in global average temperature since the mid-20th century cannot be explained by natural variability in climate, and is very likely due to the observed increase in greenhouse gas concentrations in the atmosphere as a result of human

activities, particularly emissions of carbon dioxide from fossil fuel use (IPCC 2007a, p. 5 and Figure SPM.3; Solomon

et al.

2007, pp. 21-35). Therefore, to project future changes in temperature and other climate conditions, scientists use a variety of climate models (which include consideration of natural processes and variability) in conjunction with various scenarios of potential levels and timing of greenhouse gas emissions (e.g., Meehl

et al.

2007 entire; Ganguly

et al.

2009, pp. 11555, 15558; Prinn

et al.

2011, pp. 527, 529).

The projected magnitude of average global warming for this century is very similar under all combinations of models and emissions scenarios until about 2030. Thereafter, the projections show greater divergence across scenarios. Despite these differences in projected magnitude, however, the overall trajectory is one of increased warming throughout this century under all scenarios, including those which assume a reduction of greenhouse gas emissions (Meehl

et al.

2007, pp. 760-764; Ganguly

et al.

2009, pp. 15555-15558; Prinn

et al.

2011, pp. 527, 529). (For examples of other global climate projections, see IPCC 2007b, p. 8.)

Various types of changes in climate can have direct or indirect effects on species and these may be positive or negative depending on the species and other relevant considerations, including interacting effects with existing habitat fragmentation or other nonclimate variables. There are three main components of vulnerability to climate change: Exposure to changes in climate, sensitivity to such changes, and adaptive capacity (IPCC 2007a, p. 89; Glick

et al.

2011, pp. 19-22). Because aspects of these components can vary by species and situation, as can interactions among climate and nonclimate conditions, there is no single way to conduct our analyses. We use the best scientific and commercial data available to identify potential impacts and responses by species that may arise in association with different components of climate change, including interactions with nonclimate conditions.

As is the case with all potential threats, if a species is currently affected or is expected to be affected in a negative way by one or more climate-related impacts, this does not necessarily mean the species meets the definition of a threatened or endangered species as defined under the Act. The impacts of climate change and other conditions would need to be to the level that the species is in danger of extinction, or likely to become so, throughout all or a significant portion of its range. If a species is listed as threatened or endangered, knowledge regarding the species' vulnerability to, and impacts from, climate-associated changes in environmental conditions can be used to help devise appropriate strategies for its recovery.

Climate simulations of Palmer Drought Severity Index (PSDI) (a calculation of the cumulative effects of precipitation and temperature on surface moisture balance) for the Southwest for the periods of 2006-2030 and 2035-2060 predict an increase in drought severity with surface warming. Additionally, drought still increases during wetter simulations because the effect of heat-related moisture loss (Hoerling and Eicheid 2007, p. 19). Annual mean precipitation is likely to decrease in the Southwest as well as the length of snow season and snow depth (IPCC 2007b, p. 887). Most models project a widespread decrease in snow depth in the Rocky Mountains and earlier snowmelt (IPCC 2007b, p. 891). Exactly how climate change will affect precipitation is less certain, because precipitation predictions are based on continental-scale general circulation models that do not yet account for land use and land cover change effects on climate or regional phenomena. Consistent with recent observations in changes from climate, the outlook presented for the Southwest predicts warmer, drier, drought-like conditions (Seager

et al.

2007, p. 1181; Hoerling and Eischeid 2007, p. 19). A decline in water resources with or without climate change will be a significant factor in the compromised watersheds of the desert southwest.

On August 16, 2011, the U.S. Department of Agriculture granted a request from the Governor of Arizona to assign Apache, Cochise, Graham, Greenlee, and Santa Cruz counties as primary natural disaster areas due to losses caused by drought, wildfires, and high winds. The purpose of such a designation is to make farm operators in both primary and contiguous disaster areas eligible to be considered for assistance from the Farm Service Agency (FSA) (Vilsack 2011). However, this designation is a recognition of drought in counties inhabited by spikedace and loach minnow, including Apache, Graham, and Greenlee counties. For New Mexico, the NMOSE reported that, for the first 5 months of 2011, statewide precipitation was only 35 percent of normal in New Mexico (NMOSE 2011b). They include spikedace and loach minnow on a list of species likely to be affected by drought due to loss of habitat (NMOSE 2011c). Habitat losses occur when surface waters decrease, resulting in insufficient flows which may continue to fill low areas as pool habitat, but which do not continue to have sufficient depth or velocity to create the habitat types preferred by spikedace and loach minnow.

Summary of Factor A

Spikedace and loach minnow face a variety of threats throughout their range in Arizona and New Mexico, including groundwater pumping, surface water diversions, impoundments, dams, channelization, improperly managed livestock grazing, wildfire, agriculture, mining, road building, residential development, and recreation. These activities, alone and in combination, contribute to riparian habitat loss and degradation of aquatic resources in Arizona and New Mexico.

Changes in flow regimes are expected to continue into the foreseeable future. Groundwater pumping, surface water diversions, and drought are reducing available surface flow in streams occupied by spikedace and loach minnow. These conditions are ongoing, but drought conditions are worsening and there are at least two large diversion projects in the planning stages which may result in further water withdrawals on the Verde and Gila rivers. For spikedace and loach minnow, reduced surface flow in streams can decrease the amount of available habitat by eliminating flowing portions of the stream used by the two species. In addition, stream channel alterations, such as diversion structures and channelization of streams, affect the flow regimes, substrate, and sedimentation levels that are needed for suitable spikedace and loach minnow habitat.

Impacts associated with roads and bridges, changes in water quality, improper livestock grazing, and recreation have altered or destroyed many of the rivers, streams, and watershed functions in the ranges of the spikedace and loach minnow. While fish kills are less common now than in the past, water quality issues exist in several streams, and can include contamination by cadmium, lead, nitrates, beryllium, mercury, and total dissolved solids. These contaminants can have adverse effects on the prey base of the species and can be either sublethal, affecting their overall health or ability to reproduce, or can be lethal. Construction and maintenance at bridges, improper livestock grazing, wildfire, and recreation may also remove or reduce vegetation, which can impact water temperatures. With

increased temperatures, spikedace and loach minnow may experience multiple behavioral and physiological changes at elevated temperatures, and extreme temperatures can result in death. Decreases in precipitation and increases in temperatures due to climate change and drought are likely to further limit the areas where spikedace or loach minnow can persist by causing further decreases in surface flows and potentially increases in temperature.

The combined impacts of decreased flows, increased sedimentation, increased temperatures, and impaired water quality diminish the amount of habitat available and the suitability of that habitat in some areas. These impacts are further exacerbated by predation by and competition with nonnative species and other factors, as outlined below.

B. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes

Currently, collection of spikedace and loach minnow in Arizona is prohibited by Arizona Game and Fish Commission Order 40, except where such collection is authorized by special permit (Arizona Game and Fish Department (AGFD) 2009, p. 5). The collection of these species is prohibited in the State of New Mexico except by special scientific permit (New Mexico Department of Game and Fish (NMDGF) 2010, p. 4). Because spikedace and loach minnow do not grow larger than 80 mm (3 in), we conclude that angling for this species is not a threat. No known commercial uses exist for spikedace or loach minnow. A limited amount of scientific collection occurs, but does not pose a threat to these species because it is regulated by the States. Therefore, we have determined that overutilization for commercial, recreational, scientific, or educational purposes is not a threat to spikedace or loach minnow at this time.

C. Disease or Predation

The introduction and spread of nonnative species has been identified as one of the primary factors in the continuing decline of native fishes throughout North America and particularly in the Southwest (Miller 1961, pp. 365, 397-398; Lachner

et al.

1970, p. 21; Ono

et al.

1983, pp. 90-91; Carlson and Muth 1989, pp. 222, 234; Fuller

et al.

1999, p. 1; Propst

et al.

2008, pp. 1246-1251; Pilger

et al.

2010, pp. 300, 311-312). Miller

et al.

(1989, pp. 22, 34, 36) concluded that introduced nonnative species were a causal factor in 68 percent of fish extinctions in North America in the last 100 years. For the 70 percent of fish species that are still extant, but are considered to be endangered or threatened, introduced nonnative species are a primary cause of the decline (Lassuy 1995, pp. 391-394). Release or dispersal of new nonnative aquatic organisms is a continuing phenomenon in the species' range (Rosen

et al.

1995, p. 254). Currently, the majority of native fishes in Arizona and 80 percent of native fishes in the Southwest are on either State or Federal protection lists.

Nonnative fish introductions in the southwestern United States began before 1900, and have steadily increased in frequency (Rinne and Stefferud 1996, p. 29). New species are continually being introduced through various mechanisms, including aquaculture, aquarium trade, sport fish stocking, live bait use, interbasin water transfers, and general “bait bucket transport,” where people move fish from one area to another without authorization and for a variety of purposes (Service 1994b, pp. 12-16; Service 1999, pp. 24-59). Nearly 100 kinds of nonnative fishes have been stocked or introduced into streams in the Southwest (Minckley and Marsh 2009, p. 51). Nonnative fishes known to occur within the historical range of the spikedace include channel catfish (

Ictalurus punctatus

), flathead catfish (

Pylodictis olivaris

), red shiner (

Cyprinella lutrensis

), fathead minnow (

Pimephales promelas

), green sunfish (

Lepomis cyanellus

), largemouth bass (

Micropterus salmoides

), smallmouth bass (

Micropterus dolomieui

), rainbow trout (

Oncorhynchus mykiss

), brown trout (

Salmo trutta),

mosquitofish (

Gambusia affinis

), carp (

Cyprinus carpio

), bluegill (

Lepomis macrochiris

), yellow bullhead (

Ameiurus natalis

), black bullhead (

Ameiurus melas

), and goldfish (

Carassius auratus

) (ASU 2002).

In the Gila River basin, introduction of nonnative species is considered a primary factor in the decline of native fish species (Minckley 1985, pp. 1, 68; Williams

et al.

1985, pp. 1-2; Minckley and Deacon 1991, pp. 15-17; Douglas

et al.

1994, pp. 9-11; Clarkson

et al.

2005 p. 20; Olden and Poff 2005, pp. 79-87). Aquatic and semiaquatic mammals, reptiles, amphibians, crustaceans, mollusks (snails and clams), parasites, disease organisms, and aquatic and riparian vascular plants outside of their historical range, have all been documented to adversely affect aquatic ecosystems (Cohen and Carlton 1995, pp. i-iv). The effects of nonnative fish competition on spikedace and loach minnow can be classified as either interference or exploitive. Interference competition occurs when individuals directly affect others, such as by fighting, producing toxins, or preying upon them (Schoener 1983, p. 257). Exploitive competition occurs when individuals affect others indirectly, such as through use of common resources (Douglas

et al.

1994, p. 14). Interference competition in the form of predation is discussed here, while a discussion of the history of nonnative species introductions and resulting interference competition for resources is under Factor E below.

Altered Flow Regimes and Nonnative Predators

Alterations of stream channels through channelization, surface and groundwater withdrawals are discussed above under Factor A. Propst

et al.

(2008, p. 1236) completed a study on the interaction of physical modification of stream channels coupled with the widespread introduction and establishment of nonnative aquatic species. Following evaluation of six study sites in the upper Gila River drainage, they determined that the negative association between nonnatives and native fishes indicated a complex relationship between naturally variable flows and nonnative species, and varied at the study sites (Propst

et al.

2008, p. 1236). For the West, Middle, and East Forks of the Gila River, they determined that natural flow alone would be insufficient to conserve native fish assemblages. The Tularosa and San Francisco River study sites were affected by human use (albeit at low levels), and neither site supported more than a few nonnative fishes, with none in most years. Declines of loach minnow in this area may be due to the natural variability of the system; however, the research concluded that resilience of native fish assemblages may be compromised by the presence of the nonnative species.

The Gila River study site, just downstream of the town of Cliff, was the most affected by human activity, and was exposed to the greatest number of nonnative fishes; however, over the course of the study, the native fish assemblage at the site did not change. Although not entirely explained, the researchers indicate that the lack of optimal (i.e., pool) habitat for nonnative predators and the comparative abundance of habitats (e.g., cobble riffles and shallow gravel runs) favored by native fishes partially explains the persistence of the native fish assemblage. They speculate that other factors, including thermal regime or turbidity, might also have buffered the interactions between native and nonnative fishes (Propst

et al.

2008, pp.

1246-1249). The study concludes that, while native fish assemblages may persist through drought, their resistance and resilience are compromised if nonnative predators are present. They also conclude that, while retention of natural hydrologic regimes is crucial for the persistence of native fish assemblages in arid-land streams, removal and preclusion of nonnative predators and competitors are equally important (Propst

et al.

2008, p. 1251).

Predation

Nonnative channel catfish, flathead catfish, and smallmouth bass all prey on spikedace and loach minnow, as indicated by prey remains of native fishes in the stomachs of these species (Propst

et al.

1986, p. 82; Propst

et al.

1988, p. 64; Bonar

et al.

2004, pp. 13, 16-21). Channel catfish move into riffles to feed, preying on the same animals most important to loach minnows, while juvenile flathead catfish prey on loach minnows (Service 1991a, p. 5). Smallmouth bass are known to co-occur with spikedace and are documented predators of the species (Service 1991b, p. 6; Paroz

et al.

2009, pp. 12, 18). When smallmouth bass densities increased on the East Fork Gila River, densities of native fishes decreased (Stefferud

et al.

2011, pp. 11-12). Green sunfish are also thought to be a predator, likely responsible for replacement of native species like spikedace and loach minnow. While no direct studies have been completed on predation by green sunfish on spikedace or loach minnow, they are a known predator of fish that size, and they occur within areas occupied by these species.

Declines of native fish species appear linked to increases in nonnative fish species. In 1949, for example, 52 spikedace were collected at Red Rock on the Gila River, while channel catfish composed only 1.65 percent of the 607 fish collected. However, in 1977, only 6 spikedace were located at the same site, and the percentage of channel catfish had risen to 14.5 percent of 169 fish collected. The decline of spikedace and the increase of channel catfish is likely related (Anderson 1978, pp. 2, 13, 50-51). Similarly, interactions between native and nonnative fishes were observed in the upper reaches of the East Fork of the Gila River. Prior to the 1983 and 1984 floods in the Gila River system, native fish were limited, with spikedace being rare or absent, while nonnative channel catfish and smallmouth bass were moderately common. After the 1983 flooding, adult nonnative predators were generally absent, and spikedace were collected in moderate numbers in 1985 (Propst

et al.

1986, p. 83).

The majority of areas considered occupied by spikedace and loach minnow have seen a shift from a predominance of native fishes to a predominance of nonnative fishes. For spikedace, this is best demonstrated on the upper Verde River, where native species dominated the total fish community at greater than 80 percent from 1994 to 1996, before dropping to approximately 20 percent in 1997 and 19 percent in 2001. At the same time, three nonnative species increased in abundance between 1994 and 2000 (Rinne

et al.

2004, pp. 1-2). Similar changes in the dominance of nonnative fishes have occurred on the Middle Fork Gila River, with a 65 percent decline of native fishes between 1988 and 2001 (Propst 2002, pp. 21-25).

In other areas, nonnative fishes may not dominate the system, but their abundance has increased, while spikedace and loach minnow abundance has declined. This is the case for the Cliff-Gila Valley area of the Gila River, where nonnative fishes increased from 1.1 percent to 8.5 percent, while native fishes declined steadily over a 40-year period (Propst

et al.

1986, pp. 27-32). At the Redrock and Virden valleys on the Gila River, the relative abundance in nonnative fishes in the same time period increased from 2.4 percent to 17.9 percent (Propst

et al.

1986, pp. 32-34). Four years later, the relative abundance of nonnative fishes increased to 54.7 percent at these sites (Propst

et al.

1986, pp. 32-36). The percentage of nonnative fishes increased by almost 12 percent on the Tularosa River between 1988 and 2003, while on the East Fork Gila River, nonnative fishes increased to 80.5 percent relative abundance in 2003 (Propst 2005, pp. 6-7, 23-24). Nonnative fishes are also considered a management issue in other areas including Eagle Creek, the San Pedro River, West Fork Gila River, and to a lesser extent on the Blue River and Aravaipa Creek.

Generally, when the species composition of a community shifts in favor of nonnative fishes, a decline in spikedace or loach minnow abundance occurs (Olden and Poff 2005, pp. 79-86). Propst

et al.

(1986, p. 38) noted this during studies of the Gila River between 1960 and 1980. While native species, including spikedace, dominated the study area initially, red shiner, fathead minnow, and channel catfish were more prevalent following 1980. Propst

et al.

(1986, pp. 83-86) noted that drought and diversions for irrigation first brought a decline in habitat quality, followed by the establishment of nonnative fishes in remaining suitable areas, thus reducing the availability and utility of these areas for native species. It should be noted that the effects of nonnative fishes often occur with, or are exacerbated by, changes in flow regimes or declines in habitat conditions (see Factor A above) and should be considered against the backdrop of historical habitat degradation that has occurred over time (Minckley and Meffe 1987, pp. 94, 103; Rinne 1991, p. 12).

Nonnative channel catfish, flathead catfish, and smallmouth bass are present in most spikedace habitats, including the Verde River (Minckley 1993, pp. 7-13; Jahrke and Clark 1999, pp. 2-7; Rinne 2004, pp. 1-2; Bahm and Robinson 2009b, pp. 1-4; Robinson and Crowder 2009, pp. 3-5); the Gila River (Propst

et al.

1986, pp. 14-31; Springer 1995, pp. 6-10; Jakle 1995, pp. 5-7; Propst

et al.

2009, pp. 14-17); the San Pedro River (Jakle 1992, pp. 3-5; Minckley 1987, pp. 2, 16); the San Francisco River (Papoulias

et al.

1989, pp. 77-80; Propst

et al.

2009, pp. 5-6); the Blue River (ASU 1994, multiple reports; ASU 1995, multiple reports; Clarkson

et al.

2008, pp. 3-4); the Tularosa River, East Fork Gila River, West Fork Gila River, and Middle Fork Gila River (Paroz

et al.

2009, p. 12; Propst

et al.

2009, pp. 7-13) and Eagle Creek (Marsh

et al.

2003, p. 667; ASU 2008, multiple reports; Bahm and Robinson 2009a, pp. 2-6).

Pilger

et al.

(2010, pp. 311-312) studied the food webs in six reaches of the Gila River. Their study attempted to quantify resource overlap among native and nonnative fishes. Their study determined that nonnative fishes consumed a greater diversity of invertebrates and more fish than native species, and that nonnative fishes consumed predacious invertebrates and terrestrial invertebrates more frequently than native fishes. They found that, on average, the diets of adult nonnative fishes were composed of 25 percent fish, but that there was high variability among species. Only 6 percent of the diet of channel catfish was fish, while fish made up 84 percent of the diet of flathead catfish. They found that both juvenile and adult nonnative species could pose a predation threat to native fishes.

As noted below under Factor E, nonnative fishes also compete for resources with native fishes. While nonnative fishes are preying on native fishes, small-bodied nonnative fishes are also potentially affecting native fishes through competition (discussed further under Factor E), so that native fishes are impacted by both competition and predation. Pilger

et al.

(2010, p.

312) note that removal and preclusion of nonnative predators and competitors may be necessary for conservation of native fishes in the upper Gila River in order to mitigate the effects they have on native species. Rinne and Miller (2006, pp. 91, 95) note that, in the upper Verde River, native fishes have declined precipitously since the mid-1990s. They conclude that there are declining trends of native fish abundances in the upper Gila River, and that the coexistence of native and nonnative fishes there may indicate that the threshold has not been reached, but may be imminent.

Disease

Various parasites may affect spikedace and loach minnow. Asian tapeworm (

Bothriocephalus acheilognathi

) was introduced into the United States with imported grass carp (

Ctenopharyngodon idella

) in the early 1970s. It has since become well established in areas throughout the southwestern United States. The definitive host in the life cycle of Asian tapeworm is a cyprinid fish (carp or minnow), and therefore it is a potential threat to spikedace and loach minnow, as well as other native cyprinids in Arizona. The Asian tapeworm adversely affects fish health by impeding the digestion of food as it passes through the digestive track. Emaciation and starvation of the host can occur when large enough numbers of worms feed off the fish directly. An indirect effect is that weakened fish are more susceptible to infection by other pathogens. Asian tapeworm invaded the Gila River basin and was found during the Central Arizona Project's fall 1998 monitoring in the Gila River at Ashurst-Hayden Dam. It has also been confirmed from Bonita Creek in 2010 and from Fossil Creek in 2004 and 2010 (U.S. Fish and Wildlife Service National Wild Fish Health Survey 2004, 2010). This parasite can infect many species of fish and is carried into new areas along with nonnative fishes or native fishes from contaminated areas.

The parasite (

Ichthyophthirius multifiliis

) (Ich) usually occurs in deep waters with low flow and is a potential threat to spikedace and loach minnow. Ich has occurred in some Arizona streams, probably encouraged by high temperatures and crowding as a result of drought. Ich is known to be present in Aravaipa Creek (Mpoame 1982, pp. 45-47), which is currently occupied by both spikedace and loach minnow. This parasite was observed being transmitted on the Sonora sucker (

Catostomus insignis

), although it does not appear to be host-specific and could be transmitted by other species (Mpoame 1982, p. 46). It has been found on desert and Sonoran suckers, as well as roundtail chub (Robinson

et al.

1998, p. 603). This parasite becomes embedded under the skin and within the gill tissues of infected fish. When Ich matures, it leaves the fish, causing fluid loss, physiological stress, and sites that are susceptible to infection by other pathogens. If Ich is present in large enough numbers, it can also impact respiration because of damaged gill tissue. There are recorded spikedace mortalities in captivity due to Ich.

Anchor worm (

Lernaea cyprinacea

), an external parasite, is unusual in that it has little host specificity, infecting a wide range of fishes and amphibians. Infection by this parasite has been known to kill large numbers of fish due to tissue damage and secondary infection of the attachment site (Hoffnagle and Cole 1999, p. 24). Presence of this parasite in the Gila River basin is a threat to spikedace, loach minnow, and other native fishes. In July 1992, the BLM found anchor worms in Bonita Creek. They have also been documented in Aravaipa Creek and the Verde River (Robinson

et al.

1998, pp. 599, 603-605). Both spikedace and loach minnow occur in Bonita and Aravaipa Creeks.

Yellow grub (

Clinostomum marginatum)

is a parasitic, larval flatworm that appears as yellow spots on the body and fins of a fish. These spots contain larvae of worms which are typically introduced by fish-eating birds who ingest fish infected with the parasite. Once ingested, the parasites mature and produce eggs in the intestines of the bird host. The eggs are then deposited into water bodies in the bird waste, where they infect the livers of aquatic snails. The snail hosts in turn allow the parasites to develop into a second and third larval form, which then migrates into a fish host. Because the intermediate host is a bird, and therefore highly mobile, yellow grub are easily spread. When yellow grub infect a fish they penetrate the skin and migrate into its tissues, causing damage and potentially hemorrhaging. Damage from one yellow grub may be minimal, but in greater numbers, yellow grub can kill fish (Maine Department of Inland Fisheries and Wildlife 2002a, p. 1). Yellow grub occur in many areas in Arizona and New Mexico, including Aravaipa Creek (Amin 1969, p. 436; U.S. Geological Survey (USGS) 2004, p. 71; Widmer

et al.

2006, p. 756), Oak Creek (Mpoame and Rinne 1983, pp. 400-401), the Salt River (Amin 1969, p. 436; Bryan and Robinson 2000, p. 19), the Verde River (Bryan and Robinson 2000, p. 19), and Bonita Creek (Robinson, 2011b, pers. comm.).

Black grub, also called black spot, (

Neascus

spp.) is a parasitic larval fluke that appears as black spots on the skin, tail base, fins, and musculature of a fish. As with yellow grub, adult black grub trematodes live in a bird's mouth and produce eggs, which are swallowed unharmed and released into the water in the bird's feces. Each stage of their life cycle is named. Eggs mature in the water releasing miracidia, which infect mollusks as a first intermediate host, and continue to grow, becoming redia. They then migrate into the tissues of a second intermediate host, which is typically a fish. At this stage, they are termed “cercaria.” When the cercaria penetrates and migrates into the tissues of a fish, it causes damage and possibly hemorrhaging. It then becomes encapsulated by host tissue, and melanophores, or pigmented cells, surround the outer layers, resulting in the darker color, which appears as a black spot. The damage caused by one cercaria is negligible, but in greater numbers they may kill a fish (Lane and Morris 2000, pp. 2-3; Maine Department of Inland Fisheries and Wildlife 2002b, p. 1). Black grub are present in the Verde River (Robinson et al. 1998, p. 603; Bryan and Robinson 2000, p. 21), Silver Creek, Redfield Canyon, and Fossil Creek (Robinson, 2011b, pers. comm.), and are prevalent in the San Francisco River in New Mexico (Paroz, 2011 pers. comm.).

Summary of Factor C

Both spikedace and loach minnow have been severely impacted by the predation of nonnative predators. Aquatic nonnative species have been introduced or spread into new areas through a variety of mechanisms, including intentional and accidental releases, sport stocking, aquaculture, aquarium releases, and bait-bucket release. Channel catfish, flathead catfish, and smallmouth bass appear to be the most prominent predators, although other species contribute to the decline of spikedace and loach minnow. Spikedace and loach minnow have been replaced by nonnative fishes in several Arizona streams. In addition to threats from predation, we also conclude that both spikedace and loach minnow are reasonably certain to become impacted by parasites that have been documented in the Gila River basin and that are known to adversely affect or kill fish hosts. For these reasons, we find that disease and predation are significant threats to the spikedace and loach minnow.

D. The Inadequacy of Existing Regulatory Mechanisms

Because of the complex, indirect, and cumulative nature of many of the threats to spikedace and loach minnow, existing regulatory mechanisms are inadequate to address or ameliorate the threats. Causes of the declining status of these species are a mix of many human activities and natural events, which makes them difficult to control through regulation.

State Regulations

Spikedace is listed by New Mexico as an endangered species, while loach minnow is listed as threatened (Bison-M 2010). These designations provide the protection of the New Mexico Wildlife Conservation Act. However, the primary focus of the New Mexico Wildlife Conservation Act and other State legislation is to prevent actual destruction or harm to individuals of the species. Since most of the threats to these species come from actions that do not directly kill individuals, but indirectly result in their death from the lack of some habitat requirement or an inability to reproduce, the State protection is only partially effective for this species. Similarly, spikedace and loach minnow are listed as species of concern by the State of Arizona. The listing under the State of Arizona law does not provide protection to the species or their habitats; however, AGFD regulations prohibit possession of these species (AGFD 2006, Appendix 10, p. 4).

As discussed above under Factor C, the introduction and spread of nonnative aquatic species is a major threat to spikedace and loach minnow. Neither the States of New Mexico and Arizona nor the Federal Government has adequate regulatory mechanisms to address this issue. Programs to introduce, augment, spread, or permit such actions for nonnative sport, bait, aquarium, and aquaculture species continue. Regulation of these activities does not adequately address the spread of nonnative species, as many introductions are conducted through incidental or unregulated actions.

New Mexico water law does not include provisions for instream water rights to protect fish and wildlife and their habitat. Arizona water law does recognize such provisions; however, because this change is relatively recent, instream water rights have low priority and are often overcome by more senior diversion rights. Indirectly, Arizona State law also allows surface water depletion by groundwater pumping.

A limited amount of scientific collection occurs under State permitting, as authorized by the special rule for the two species, but does not pose a threat to these species because it is regulated by the States.

Federal Regulations

Many Federal statutes potentially afford protection to spikedace and loach minnow. A few of these are section 404 of the Clean Water Act (33 U.S.C. 1251

et seq.

), Federal Land Policy and Management Act (43 U.S.C. 1701-1782), National Forest Management Act (16 U.S.C. 1600

et seq.

), National Environmental Policy Act (NEPA), and the Act. However, in practice these statutes have not been able to provide sufficient protection to prevent the downward trend in the populations and habitat of spikedace and loach minnow and the upward trend in threats. Section 404 of the Clean Water Act regulates placement of fill into waters of the United States, including most of spikedace and loach minnow habitat. However, many actions highly detrimental to spikedace and loach minnow and their habitats, such as gravel mining and irrigation diversion structure construction and maintenance, are often exempted from the Clean Water Act. Other detrimental actions, such as bank stabilization and road crossings, are covered under nationwide permits that receive little or no Service review. A lack of thorough, site-specific analyses for projects can allow substantial adverse effects to spikedace, loach minnow, and their habitat.

The Federal Land Policy and Management Act and National Forest Management Act provide mechanisms for protection and enhancement of spikedace, loach minnow, and their habitat on Federal lands. The USFS and the BLM have made significant progress on some stream enhancements (Fossil Creek, Blue River, Hot Springs Canyon, and Bonita Creek). However, despite the protection and enhancement mechanisms in these laws, competing multiple uses, limited funding and staffing have resulted in few measureable on-the-ground successes, and the status of these species has continued to decline.

Spikedace and loach minnow are currently listed as threatened under the Act and therefore are afforded the protections of the Act. Special rules were promulgated for spikedace and loach minnow in 1986, which prohibit taking of the species, except under certain circumstances in accordance with applicable State fish and wildlife conservation laws and regulations. Violations of the special rules are considered violations of the Act (50 CFR 17.44(p) for spikedace and 50 CFR 17.44(q) for loach minnow). As a result of the special rules for spikedace and loach minnow, the AGFD is issuing scientific collecting permits. This authority was granted at 50 CFR 17.44(p) for spikedace and 50 CFR 17.44(q) for loach minnow. This is confirmed through Arizona Commission Order 40 and New Mexico special permit (19 New Mexico Administrative Code 33.6.2).

Under section 7 of the Act, Federal agencies must insure that any action they authorize, fund, or carry out is not likely to jeopardize the continued existence of any endangered or threatened species or result in the adverse modification or destruction of designated critical habitat. The Service promulgated regulations extending take prohibitions under section 9 for endangered species to threatened species. Prohibited actions under section 9 include, but are not limited to, take (i.e., harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or attempt to engage in such activity). Critical habitat designation alerts the public that the areas designated as critical habitat are important for the future recovery of the species, as well as invoking the review of these areas under section 7 of the Act with regard to any possible Federal actions in that area.

Section 10 of the Act allows for the permitting of take in the course of otherwise lawful activities by private entities, and may involve habitat conservation plans which can ultimately benefit spikedace or loach minnow. The habitat conservation plan (HCP) prepared by Salt River Project (SRP) is expected to benefit spikedace and loach minnow in the Verde River.

Spikedace and loach minnow have been protected under the Act since their listing in 1986. While the Act provides prohibitions against take, and allows for the development of HCPs, the species have continued to decline. To date, section 7 consultation has not been an effective tool in addressing this decline. This is due in part to the fact that some causes of the decline, such as competition and predation with nonnative aquatic species, decreases in surface flows due to drought, and habitat losses caused by wildfires are not covered by the Act. In addition, water diversions are often “grandfathered” into existing law and are therefore not subject to section 7.

Summary of Factor D

Despite the prohibitions against take, which have been in place since the

species were listed in 1986, spikedace and loach minnow have continued to decline. While section 7 consultation may be effective in addressing impacts from Federal actions such as a road construction project or implementation of an allotment management plan, they are not effective at minimizing losses to the species from competition and predation with nonnative species, the impacts of drought or climate change, or the effects of wildfires. Review under the CWA is lacking, and the Federal Land Policy and Management Act and National Forest Management Act are not currently having a positive effect on the species. In summary, existing regulatory mechanisms that prohibit taking of the two species have been in place for decades, however, these regulations are not adequate to address the significant habitat effects, particularly water diversion and the distribution and abundance of nonnative fishes, affecting spikedace and loach minnow. Because existing regulatory mechanisms do not provide adequate protection for these species or their habitats throughout their ranges, we conclude the inadequacy of existing regulatory mechanisms is a significant threat to the spikedace and loach minnow.

E. Other Natural or Manmade Factors Affecting the Species' Continued Existence

Nonnative Fishes

As described under Factor C above, nonnative fishes pose a significant threat to Gila River basin native fishes, including spikedace and loach minnow (Minckley 1985, pp. 1, 68; Williams

et al.

1985, pp. 3, 17-20; Minckley and Deacon 1991, pp. 15-17). Competition with nonnative fish species is considered a primary threat to spikedace and loach minnow. See Factor C for the discussion of predation by nonnative fish species.

As with many fish in the West, spikedace and loach minnow lacked exposure to a wider range of species over evolutionary time, so that they seem to lack the competitive abilities and predator defenses developed by fishes from regions where more species are present (Moyle 1986, pp. 28-31; Douglas

et al.

1994, pp. 9-10). As a result, the native western fish fauna is significantly impacted by interactions with nonnative species. The introduction of more aggressive and competitive nonnative fish has led to significant losses of spikedace and loach minnow (Douglas

et al.

1994, pp. 14-17). Nonnative fishes known to occur within the historical range of spikedace and loach minnow in the Gila River basin include channel catfish, flathead catfish, red shiner, fathead minnow, green sunfish, largemouth bass, smallmouth bass, rainbow trout, western mosquitofish, carp, warmouth (

Lepomis gulosus

), bluegill, yellow bullhead, black bullhead, and goldfish (Miller 1961, pp. 373-394; Nico and Fuller 1999, pp. 16, 21-24; Clark 2001, p. 1; AGFD 2004, Bahm and Robinson 2009b, p. 3).

The aquatic ecosystem of the central Gila River basin has relatively small streams with warm water and low gradients, and many of the native aquatic species are small. In these areas, small, nonnative fish species pose a threat to spikedace and loach minnow (Deacon

et al.

1964, pp. 385, 388). Examples of this are the impacts of mosquitofish and red shiner, which may compete with, or predate upon, native fish in the Gila River basin (Meffe 1985, pp. 173, 177-185; Douglas

et al.

1994, pp. 1, 13-17). However, negative interactions also occur between small native and large nonnative individuals. On the East and Middle Forks of the Gila River, where large nonnative predators were comparatively common, small native species were uncommon or absent. Conversely, on the West Fork Gila River, when large nonnative predators were rare, most small-bodied and young of large-bodied native fishes persisted (Stefferud

et al.

2011, pp. 1409-1411).

For spikedace and loach minnow, every habitat that has not been renovated or protected by barriers has at least six nonnative fish species present, at varying levels of occupation. In addition to nonnative fishes, parasites have been introduced incidentally with nonnative species and may be deleterious to spikedace and loach minnow populations. Nonnative crayfish (

Orconectes virilis

) have invaded occupied spikedace and loach minnow habitats (Taylor

et al.

1996, p. 31; Robinson and Crowder 2009, p. 3; Robinson

et al.

2009b, p. 4; USGS 2009, p. 1). Crayfish are known to eat fish eggs, especially those bound to the substrate (Dorn and Mittlebach 2004, p. 2135), as is the case for spikedace and loach minnow. Additionally, crayfish cause decreases in macroinvertebrates, amphibians, and fishes (Hanson

et al.

1990, p. 69; Lodge

et al.

2000, p. 11). Several of the nonnative species now in spikedace and loach minnow habitats arrived there since the species were listed, such as red shiner in Aravaipa Creek (Stefferud and Reinthal 2005, p. 51) and Asian tapeworm in the middle Gila River.

Competition can be classified as either interference competition or exploitive competition. Interference competition occurs when individuals directly affect others, such as by fighting, producing toxins, or preying upon them (Schoener 1983, p. 257). Exploitive competition occurs when individuals affect others indirectly, such as through use of common resources (Douglas

et al.

1994, p. 14). Exploitive competition in the form of predation is discussed above under Factor C. Interference competition occurs with species such as red shiner. Nonnative red shiners compete with spikedace for suitable habitats, as the two species occupy essentially the same habitat types. The red shiner has an inverse distribution pattern in Arizona to spikedace (Minckley 1973, p. 138). Where the two species occur together, there is evidence of displacement of spikedace to less suitable habitats than previously occupied (Marsh

et al.

1989, pp. 67, 107). As a result, if red shiners are present, suitable habitat for spikedace is reduced. In addition, the introduction of red shiner and the decline of spikedace have occurred simultaneously (Minckley and Deacon 1968, pp. 1427-1428; Douglas

et al.

1994, pp. 13, 16-17). The red shiner was introduced in the mainstem Colorado River in the 1950s, spreading upstream to south-central Arizona by 1963, and by the late 1970s eastward into New Mexico. Spikedace disappeared at the same time and in the same progressively upstream direction, likely as a result of interactions with red shiner and in response to impacts of various water developments (Minckley and Deacon 1968, pp. 1427-1428; Minckley and Deacon 1991, pp. 7, 15; Douglas

et al.

1994, pp. 13-17).

One study focused on potential impacts of red shiner on spikedace in three areas: (1) Portions of the Gila River and Aravaipa Creek having only spikedace; (2) a portion of the Verde River where spikedace and red shiner co-occurred for three decades; and (3) a portion of the Gila River where red shiner invaded areas and where spikedace have never been recorded. The study indicated that, for reaches where only spikedace were present, spikedace displayed a preference for slower currents and smaller particles in the substrate than were generally available throughout the Gila River and Aravaipa Creek systems. Where red shiner occur in the Verde River, the study showed that red shiner occupied waters that were generally slower with smaller particle sizes in the substrate than were, on average, available in the system. The study concludes that in areas where spikedace co-occurrs with

red shiner, red shiner remain in the preferred habitat, while spikedace move into currents swifter than typically occupied (Douglas

et al.

1994, pp. 14-16). The areas with swifter currents are likely less suitable for spikedace, as evidenced by their nonuse until such competition occurs. Red shiners are known to occur in the Verde River (Minckley 1993, p. 10; Jahrke 1999, pp. 2-7; Bahm and Robinson 2009b, pp. 3-5), Aravaipa Creek (Reinthal, 2011, pp. 1-2), Blue River (ASU 2004, multiple reports; ASU 2005, multiple reports), and Gila River (Minckley 1973, pp. 136-137; Marsh

et al.

1989, pp. 12-13; Propst

et al.

2009, pp. 14-18).

As with spikedace, exploitive competition also appears to occur between red shiner and loach minnow. Red shiners occur in all places known to be formerly occupied by loach minnow, and are absent or rare in places where loach minnow persists. Because of this, red shiner has often been implicated in the decline of loach minnow. Loach minnow habitat is markedly different than that of red shiner, so interaction between the two species is unlikely to cause shifts in habitat use by loach minnow (Marsh

et al.

1989, p. 39). Instead, studies indicate that red shiner move into voids left when native fishes such as loach minnow are extirpated due to habitat degradation in the area (Bestgen and Propst 1986, p. 209). Should habitat conditions improve and the habitat once again become suitable for loach minnow, the presence of red shiner may preclude occupancy of loach minnow, although the specific mechanism of this interaction is not fully understood. Prior to 1960, the Glenwood-Pleasanton reach of the San Francisco River supported a native fish assemblage of eight different species. Post-1960, four of these species became uncommon, and ultimately three of them were extirpated. In studies completed between 1961 and 1980, it was determined that loach minnow was less common than it had been, while the diversity of the nonnative fish community had increased in comparison to the pre-1960 period. Following 1980, red shiner, fathead minnow, and channel catfish were all regularly collected. Drought and diversions for irrigation resulted in a decline in habitat quality, with canyon reaches retaining most habitat components for native species. However, establishment of nonnative fishes in the canyon reaches has reduced the utility of these areas for native species (Propst

et al.

1988, pp. 51-56).

Western mosquitofish were introduced outside of their native range to help control mosquitoes. Because of their aggressive and predatory behavior, mosquitofish may negatively affect populations of small fishes through predation and competition (Courtenay and Meffe 1989, pp. 320-324). Introduced mosquitofish have been particularly destructive to native fish communities in the American West, where they have contributed to the elimination or decline of populations of federally endangered and threatened species, such as the Gila topminnow (

Poeciliopsis occidentalis occidentalis

) (Courtenay and Meffe 1989, pp. 323-324). Pilger

et al.

(2010, p. 312) found that the generalist feeding strategy of smallbodied nonnative fishes could further affect native fishes through competition, particularly if there is a high degree of overlap in habitat use. In their study on the upper Gila River, they determined that the diets of nonnative, small-bodied fishes and all age groups of native fishes overlapped, so that the presence of both juvenile and adult nonnative species could pose a competitive threat to native fishes spikedace and loach minnow (Pilger

et al.

2010, p. 311). Western mosquitofish represent an additional challenge for spikedace and loach minnow management, in that they are harder to effectively remove during stream renovation efforts. In the desert Southwest, the habitat conditions are so limited that native fish reintroductions can occur only in those areas where the competition and predation of nonnative fishes can be physically precluded, such as above a fish barrier.

Drought

The National Integrated Drought Information System (2011) classifies drought in increasing severity categories from abnormally dry, to moderate, severe, extreme, and, most severe, exceptional. The southwestern United States is currently experiencing drought conditions classified as moderate to exceptional. Drought conditions are reported as abnormally dry to moderate for the Verde River, with the remainder of the critical habitat streams in severe to extreme in Arizona. Critical habitat areas in New Mexico fall within the severe to extreme drought categories (National Integrated Drought Information System 2011).

While spikedace and loach minnow have survived many droughts in their evolutionary histories, drought may have more of an impact on the species due to already reduced habitat suitability from other effects, as described above. In some areas of spikedace and loach minnow habitat, drought results in lower streamflow, and consequently warmer water temperatures beyond the species' tolerance limits, and more crowded habitats with higher levels of predation and competition. In other areas, drought reduces flooding that would normally rejuvenate habitat and tend to reduce populations of some nonnative species, which are less adapted to the large floods of southwestern streams (Minckley and Meffe 1987, pp. 94, 104; Stefferud and Rinne 1996a, p. 80). The combined effects of drought with ongoing habitat loss and alteration; increased predation, competition, and disease from nonnative species; and the general loss of resiliency in highly altered aquatic ecosystems have had and continue to have negative consequences for spikedace and loach minnow populations.

Genetics

Each remaining population of spikedace is genetically distinct. Genetic distinctiveness in the Verde River and Gila River fishes indicates that these populations have been historically isolated (Tibbets and Dowling 1996, (pp. 1285-1291); Anderson and Hendrickson 1994, pp. 148, 150-154). The center of the historical distribution for spikedace is permanently altered, and the remaining populations are isolated and represent the fringes of the formerly occupied range. Isolation of these populations has important ramifications for the overall survival of the species. Loss of any population may be permanent, as there is little ability to repopulate isolated areas, due largely to habitat alterations in areas between remaining populations (Propst

et al.

1986, pp. 38, 86). No genetic exchange is possible between the remaining populations of spikedace without human assistance. In addition, because genetic variation is important to the species' fitness and adaptive capability, losses of genetic variation represent a threat to the species (Meffe and Carroll 1997, pp. 162-172).

Spikedace in the upper Verde River are genetically different than those that were translocated to Fossil Creek; however, there is a minimal opportunity for the two populations to interbreed due to the length of the river between the two occupied areas. While the Verde River supports many of the habitat features for spikedace, it currently supports a high number of nonnative species that compete with, and prey on, spikedace. We anticipate that, until extensive management takes place, spikedace in the two areas will remain isolated. The spikedace translocation in Fossil Creek has been in place for

approximately 4 years. It is not known if that translocation effort will succeed.

As with spikedace, each remaining population of loach minnow is genetically distinct. Genetic subdivision into three geographic regions indicates that gene flow has been low but not historically absent (Tibbets 1993, pp. 22-24, 33). The center of the loach minnow's historical distribution is permanently gone, and the remaining populations are isolated and represent the fringes of the formerly occupied range. Isolation of these populations has important ramifications for the overall survival of the species. Loss of any population may be permanent, as there is little ability to repopulate isolated areas, due largely to habitat alterations in areas between remaining populations (Propst

et al.

1988, p. 65). No genetic exchange is likely between the remaining populations of loach minnow without human assistance. As noted for spikedace, genetic variation is important to the species' fitness and adaptive capability, and losses of genetic variation represent a threat to the species (Meffe and Carroll 1997, pp. 162-172).

Flow Regime, Nonnative Fishes, and Connectivity

The competitive effects of nonnative fish species are often exacerbated by changes in flow regimes or declines in habitat conditions associated with water developments, as discussed above, and should be considered against the backdrop of historical habitat degradation that has occurred over time (Minckley and Meffe 1987, pp. 94, 103; Rinne 1991, p. 12). Stefferud and Rinne (1996b, p. 25) note that a long history of water development and diversion coupled with nonnative fish introductions has resulted in few streams in Arizona retaining their native fish communities. Using the Gila River as an example, Propst

et al.

(1988, p. 67) note that natural (e.g., drought) and human-induced (e.g., flow level reductions through irrigation diversion) factors combined to reduce loach minnow abundance in the Gila River. They note that where canyon habitat would normally continue to contain surface flows and suitable habitat for loach minnow, the establishment of nonnative fishes in canyon reaches has reduced their suitability as habitat for the minnow. Minckley and Douglas (1991, pp. 7-17) concluded that, for fishes native to the Southwest, the combination of changes in stream discharge patterns and nonnative fish introductions has reduced the range and numbers of all native species of fish, and has led to extinction of some.

Recent work completed by Propst

et al.

(2008) indicates that individual factors, such as the presence of nonnative fishes or existing flow regimes may have impacts on native fish species, but it is likely that the interaction of these factors causes a decline in native fish species. In studies on the upper Gila River drainage in New Mexico, Propst

et al.

(2008) determined that flow regime was a primary factor in shaping fish assemblages, with the greatest densities of native fishes occurring in those years with higher stream discharges. However, they also found that pressure from competition and predation with nonnative fishes also affected fish assemblages. They concluded that there was a negative association between nonnatives and native fishes, which indicated that there is a complex relationship between naturally variable flows and nonnative species, and that natural flow alone was not enough to conserve native fish species (Propst

et al.

2008, p. 1246). The way in which these factors interact varied from stream to stream in the study.

Propst

et al.

(2008) also note the importance of connectivity, stating that it is critical to ensuring the long-term persistence of native fishes. They note that loach minnow, while still present throughout much of its historical range, has been apparently extirpated from four of six sites in 10 years or less, and that loss of connectivity among populations has reduced the likelihood that many will recover naturally, even if causes for elimination are removed. They conclude that “It is almost certain similar, but undocumented, losses have occurred throughout the species range, and its status is much more fragile than presumed” (Propst

et al.

2008, p. 1251). However, where flows remain suitable, and connectivity is maintained, there is the inherent risk of exposure to nonnative species traveling from one area to another. They conclude that retention of natural hydrologic regimes and preclusion of nonnative predators and competitors are equally important (Propst

et al.

2008, p. 1251).

Summary of Factor E

The reduced distribution and decreasing numbers of spikedace and loach minnow make the two species susceptible to natural environmental variability, including climate conditions such as drought. However, research indicates that it is the interaction of individual factors such as nonnative fishes and altered flow regimes that is causing a decline of native fish species. Native fishes are unable to maintain a competitive edge in areas where resources are already limited, and these resources are likely to become more limited due to water developments and drought. Increased water demands are likely to further limit the areas where spikedace or loach minnow can persist. We therefore conclude that the spikedace and loach minnow are threatened by other natural or manmade factors.

Reclassification Determination

As required by the Act, we considered the five factors in assessing whether the spikedace and loach minnow are endangered or threatened throughout all or a significant portion of their range. We carefully assessed the best scientific and commercial information available regarding reclassification of the spikedace and the loach minnow from threatened to endangered. There are many threats to both species, including habitat loss and modifications (Factor A) caused by historical and ongoing land uses such as water diversion and pumping, livestock grazing, and road construction. However, competition with, or predation by, nonnative species, such as channel and flathead catfish, green sunfish, and red shiner, is likely the largest remaining threat to the species (Factors C and E). In addition, recent research indicates that the combination of altered flow regimes and nonnative fishes together are causing declines in native fishes. Existing regulatory mechanisms (Factor D) have not proven adequate to halt the decline of spikedace or loach minnow or habitat losses since the time of their listing as threatened species. In addition, the warmer, drier, drought-like conditions predicted to occur due to climate change (Factor A) will further reduce available resources for spikedace and loach minnow.

In 1991, we completed a 5-year review for spikedace and loach minnow in which we determined that the species' status was very precarious and that a change in status from threatened to endangered was warranted. Since that time, although some recovery actions have occurred, the majority of the areas historically occupied by spikedace and loach minnow have experienced a shift from a predominance of native fishes to a predominance of nonnative fishes. The low numbers of spikedace and loach minnow, their isolation in tributary waters, drought, ongoing water demands, and other threats leads us to conclude the species are now in danger of extinction throughout their ranges.

We determined in 1994 that reclassifying spikedace and loach minnow to endangered status was warranted but precluded (59 FR 35303,

July 11, 1994), and restated this conclusion on January 8, 2001 (66 FR 1295). We reanalyzed the determination each year in our Candidate Notice of Review, and determined that reclassification to endangered is warranted, in the Candidate Notice of Review published on November 9, 2009 (74 FR 57804). Spikedace and loach minnow were not addressed in the Candidate Notice of Review published in 2011, as this reclassification determination was funded in FY 2010. Candidate assessments are not reviewed on an annual basis once they are funded.

Both species have been reduced in range and numbers since the time of listing through either localized extirpations, reduced distribution within occupied drainages, or reductions in numbers within a given drainage. Spikedace and loach minnow are both extirpated from the Salt and San Pedro rivers. Spikedace are additionally extirpated from the San Francisco River, while loach minnow are extirpated from the Verde River.

In terms of reduced distribution since listing within occupied drainages, spikedace currently have a much reduced distribution in the Verde River, where the known locations at listing occurred over approximately 25 percent of the previously occupied area. Loach minnow are reduced in distribution in the San Francisco and Tularosa rivers, occurring in a portion up and downstream of the Whitewater Creek confluence and again farther upstream of the Tularosa River. Spikedace and loach minnow are both reduced in distribution in the East and Middle Forks of the Gila River, occurring closer to the confluence with the Gila River, but no longer extending as far upstream as in the past. The strongholds for both species are Aravaipa Creek in Arizona and the Gila River mainstem in New Mexico, but more recent records indicate at least small reductions in the up and downstream extent of their distributions in these systems.

In addition to extirpations and reductions in range, some spikedace and loach minnow populations persist, but are at reduced numbers. In the Verde River, spikedace numbers were frequently in the hundreds, with a high of 407 in 1986, but reduced to double and then single digits in the late 1980s and 1990s (ASU 2002). While spikedace likely still occur in the Verde River, they are at extremely low numbers and on the verge of extirpation. Survey records indicate a similar situation exists for both spikedace and loach minnow in Eagle Creek. Loach minnow are in extremely low numbers in the North Fork East Fork Black River as well (ASU 2002).

Two of the primary threats to spikedace and loach minnow are nonnative fishes and loss of water due to diversions, pumping, drought, or other causes, as detailed above. Recently, Propst

et al.

(2008) indicated that individual factors, such as the presence of nonnative fishes or existing flow regimes may have impacts on native fish species, but it is likely that the interaction of these factors may cause a decline in native fish species. Past events (both legal and alleged illegal) resulted in the establishment of at least 60 nonnative fish species, at least three nonnative amphibians (American bullfrog, Rio Grande leopard frog, American tiger salamander), at least four invertebrates (two species of crayfish, Asiatic clam, and New Zealand mud snail), and several diseases or parasites that affect native fish or amphibians in areas across Arizona (

See

Service 2002a for additional information). The impacts of nonnative fishes on spikedace and loach minnow are detailed above. Nonnative aquatic species are known to occur in varying levels in every stream occupied by spikedace or loach minnow, with the exception of streams in the early stages of renovation and/or reintroduction projects, such as Hot Springs Canyon. Nonnative species are considered a serious cause of the decline of the two species in all streams except for Aravaipa Creek and the mainstem Gila River in New Mexico; however, nonnatives are present in these streams as well.

Alteration or reductions of stream flow is a concern in many areas as well, including the Verde River, Salt River, San Pedro River, Gila River, Eagle Creek, and San Francisco River. In these areas, diversion structures may cause stream levels to drop or become dewatered, especially during drought and during the drier months. Future water needs in the arid southwest, coupled with the ongoing drought and climate change, are likely to increase the number of dewatered areas, the size of the dewatered areas, and the length of time for which dewatering occurs. Additional, pending water development projects have been identified above.

Recovery actions have occurred at Hot Springs Canyon, Redfield Canyon, Fossil Creek, Bonita Creek, and the San Francisco River in New Mexico, and have focused on building barriers to nonnative fishes or using existing structures as barriers. In some instances, chemical and/or mechanical removal of nonnative species has occurred. To date, these projects have been costly, requiring millions of dollars for barrier construction, and extensive time and costs for personnel involved in the renovation. Sufficient time has not yet elapsed to determine the success of these projects. Fossil Creek is showing early signs of success for spikedace (Robinson 2011a, p. 1), but the downstream barrier has been breached by nonnatives on one occasion since the project began in 2007. Bonita Creek was reinvaded, despite its barrier. Redfield Canyon currently has inadequate flows to support either species. Regardless of the success of these efforts, Hot Springs Canyon and Redfield Canyon flow into the dry portions of the San Pedro River so are not connected to any other populations of spikedace or loach minnow. Fossil Creek does flow into the active channel of the Verde River, but the Verde River at that confluence is currently dominated by nonnatives. Bonita Creek flows into the Gila River, which is also dominated by nonnatives and ultimately becomes dewatered as well. Therefore, the recovery actions completed to date, while allowing the species to persist, have limited ability to help recover the species at this time.

An additional complication in recovery of the species is the lack of available suitable habitat. The species are both currently found in isolated areas, with little opportunity for expansion or for genetic interchange. The Verde River feeds into two reservoirs, effectively isolating it from the Salt River. Those portions of the Salt River that were historically occupied by the species now have four dams and reservoirs. The San Pedro River is dewatered in some areas, especially downstream of known historical distribution. Aravaipa Creek, while supporting the largest population of the two species in Arizona, ends at a dry stretch of the San Pedro River. Those portions of Eagle Creek occupied by the two species occur above a diversion dam, downstream of which nonnative levels are high. Eagle Creek then joins the Gila River, which is also dominated by nonnative fishes. Downstream of the occupied area in the Gila River, which supports the largest known populations of the species, there are water diversions that ultimately result in a dry stream channel as the river travels into Arizona from New Mexico.

In summary, spikedace and loach minnow previously had a relatively widespread distribution covering portions of Arizona, New Mexico, and northern Mexico. Both species have suffered major reductions in numbers and range over time due to persistent threats such that spikedace are now estimated to occur in only 10 percent of

their former range, while loach minnow occur in 10 to 20 percent of their former range. Currently, only small, isolated populations of these species remain, with limited to no opportunities for interchange between populations or expansion of existing areas, making the species more vulnerable to threats including reproductive isolation. The two primary threats of nonnative aquatic species competition and predation and alteration or diminishment of stream flows are persistent, and research indicates that the combination of the two is leading to declines of native species such as spikedace and loach minnow (Propst

et al.

2008). The ongoing drought and climate conditions aggravate the loss of water in some areas, and future water development projects have been identified. Finally, the opportunities for expansion of the two species' range are limited by dams, reservoirs, dewatering, and nonnative species distribution.

Based on this information, as well as the above review of the best scientific and commercial information available, we find that both species are currently in danger of extinction and therefore meet the definition of endangered species under the Act. Because we have determined that these species are currently on the brink of extinction and are not in danger of extinction in the foreseeable future, we have determined that the correct status for the species under the Act is endangered. As a result, we are reclassifying both spikedace and loach minnow from threatened species to endangered species. With this reclassification of spikedace and loach minnow to endangered status, we remove the special rules for these species at 50 CFR 17.44(p) and 17.44(q), respectively. Special rules apply only to threatened species; therefore, as spikedace and loach minnow are now listed as endangered, these special rules no longer apply.

Available Conservation Measures

Conservation measures provided to spikedace and loach minnow under the Act include several reintroduction and augmentation projects. Some of these projects have already begun; others are in the planning stage. Project planning is under way for renovation efforts in Blue River and Spring Creek in Arizona. Other recovery actions include reintroduction or translocation of spikedace into streams within its historical range. In 2007, spikedace were translocated into Hot Springs Canyon, Redfield Canyon, and Fossil Creek. In 2008, spikedace were translocated into Bonita Creek in Arizona and reintroduced to the San Francisco River in New Mexico. Monitoring has occurred at each of these sites annually, with annual augmentations at Hot Springs Canyon, Redfield Canyon, and Fossil Creek in subsequent years when fish are available, up to and including 2011. Spikedace were augmented in the San Francisco River in 2009, but monitoring and augmentations did not occur in 2010 or 2011 due to a lack of adequate staffing and resources. Due to a reinvasion by nonnative species, augmentations are temporarily on hold at Bonita Creek.

Several translocation projects for loach minnow are also in the planning stages. These projects may occur with or without construction of fish barriers. Loach minnow may also benefit from the Blue River and Spring Creek renovation projects mentioned above. Additional recovery actions include translocations or reintroduction of loach minnow into streams within its historical range. In 2007, translocations of loach minnow occurred at Hot Springs Canyon, Redfield Canyon, and Fossil Creek. Monitoring of these sites occurs annually, and the sites have been augmented annually when fish are available, up to and including 2011. In 2008, loach minnow were translocated into Bonita Creek, Arizona. Monitoring occurs annually at this site; however, due to a reinvasion by nonnative species, augmentations are temporarily on hold.

The AGFD and Bureau of Reclamation continue to fund equipment and staff to run the Bubbling Ponds Native Fish Research Facility through the Gila River Basin Native Fishes Conservation Program (formerly known as the Central Arizona Project Fund Transfer Program). Salt River Project's habitat conservation plan was signed in 2008, and is expected to benefit both the spikedace and the loach minnow in the Verde River watershed. Also in 2008, AGFD staff managed original source stock and their progeny at the Bubbling Ponds facility, totaling 740 Gila River spikedace, 1,650 Aravaipa Creek spikedace, 670 Blue River loach minnow, and 3,250 Aravaipa Creek loach minnow. Plans are under way to bring in stock from every extant population of loach minnow, including those in the San Francisco River, the three forks of the Gila River, the upper Gila River in New Mexico, and the Eagle and Black River system in Arizona. Bubbling Ponds will serve as a refuge for some populations, and as a captive breeding facility for others, depending on the status of the population and availability of translocation sites.

In an effort to minimize impacts from nonnative fish interactions, the NMDGF initiated a nonnative removal effort in the Forks area in 2007, and at Little Creek (a tributary to West Fork Gila River) in 2010. These efforts are expected to continue.

Critical Habitat Designations for Spikedace and Loach Minnow

Summary of Changes From Proposed Rule

As noted in our October 4, 2011, notice of availability (NOA) (76 FR 61330), we used three criteria in the proposed rule to evaluate if unoccupied habitat was essential to the survival and recovery of the species. One of the criteria evaluated the potential of a stream segment to “connect to other occupied areas, which will enhance genetic exchange between populations.” After additional review of the stream segments proposed for critical habitat, we concluded there were no stream segments that met this criterion, and we removed it as an element of the ruleset. We continue to believe that both loach minnow and spikedace conservation will require genetic exchange between the remaining populations to allow for genetic variation, which is important for species' fitness and adaptive capability. We also acknowledge that areas equally important to the conservation of the species, outside of the critical habitat designations, will be necessary for long-term conservation, subject to future on-the-ground recovery actions and 7(a)(1) opportunities. Based on information we received during the comment periods on the proposed rule, several changes have been made to the areas designated as critical habitat in this final rule. These changes are summarized in Table 1 below.

Table 1—Changes in Stream Segments Included Within the Critical Habitat Designations for Loach Minnow and Spikedace

Stream

From km (mi)

To km (mi)

Change in km (mi)

San Francisco River *

180.7 (112.3)

203.6 (126.5)

Addition of 22.8 (14.2).

Bear Creek *

0.0 (0.0)

31.4 (19.5)

Addition of 31.4 (19.5).

Redfield Canyon

22.5 (14.0)

6.5 (4.0)

Reduction of 16.0 (10.0).

Hot Springs Canyon

19.0 (11.8)

9.3 (5.8)

Reduction of 9.7 (6.0).

Fossil Creek

7.5 (4.7)

22.2 km (13.8 mi)

Addition of 14.6 (9.1).

* This change made for loach minnow only.

San Francisco River.

As noticed in the NOA (76 FR 61330; October 4, 2011), we are correcting an error made in the proposed rule by extending that portion of the San Francisco River designated for loach minnow by 22.8 km (14.2 mi). The mileage for spikedace remains the same as was in the proposed rule (75 FR 66482; October 28, 2010); however, we had intended to include the same mileage for loach minnow as was in the 2007 critical habitat designation as this area is currently occupied by loach minnow, as this area meets the definition of critical habitat for loach minnow. The total mileage included on the San Francisco River for loach minnow was changed from 180.7 km (112.3 mi) in the revised proposed rule to 203.6 km (126.5 mi) in this final rule. This change has been incorporated in this final rule. The mileage for spikedace remains the same as in the revised proposed rule.

Bear Creek.

We noted in the NOA that we intended to add portions of Bear Creek to the designation for loach minnow, based on occupancy of this area by loach minnow. The NOA noted that we were adding 31.4 km (19.5 mi) of Bear Creek from its confluence with the Gila River upstream to the confluence with Sycamore and North Fork Walnut creeks. We consider those portions of Bear Creek included within the final designation to have been occupied at listing, as described in the NOA, although records were not known until 2005 and 2006. These areas meet the definition of critical habitat for loach minnow. As noted in our NOA, we recognize that portions of this stream are intermittent, but also acknowledge that streams with intermittent flows can function as connective corridors through which the species may move when the area is wetted. We have reviewed all of the information received, and conclude that inclusion of Bear Creek is appropriate at this time. We do not anticipate that loach minnow will occupy the lowermost portions of the Creek when they are dry, but we have determined that that area has value as a connective corridor to the mainstem Gila River during high-flow events.

It should be noted that the low number of fish does not, in all likelihood, represent the total number of fish present, as sampling rarely results in capture of all individuals present. Regardless, the number of fish present in Bear Creek is low. However, Bear Creek is a tributary to an occupied stream, and is within the historical range of the species. Loach minnow are currently much reduced in their overall distribution compared to historical conditions. The threats assessment above outlines current threats, which are numerous. While reintroduction projects are under way, the success of those efforts is currently limited. Streams are not abundant in the desert southwest. Because this area provides suitable habitat and is occupied by loach minnow, we conclude that it is essential to the conservation of the species.

Redfield and Hot Springs Canyons.

In response to comments received during the second comment period, we have reevaluated the extent of each stream included within the designations, and concluded that they do not meet the definition of critical habitat for either spikedace or loach minnow. With further review, we have determined that, although connective habitat is important, the area previously retained as connective habitat (i.e., between the barrier location and the San Pedro River) currently connects to dewatered portions of the San Pedro River. We have therefore shortened the overall stretch of each stream to include just those sections currently supporting perennial flows. For Redfield Canyon, the designations changed from 22.5 km (14.0 mi) in the revised proposed rule to approximately 6.5 km (4.0 miles) in this final rule, and include that portion of the stream from the confluence with Sycamore Canyon downstream to the barrier constructed at Township 11 South, Range 19 East, section 36.

For Hot Springs Canyon, we are making similar changes. The barrier location and the downstream extent of perennial flows are approximately one mile apart. As with Redfield Canyon, Hot Springs Canyon ultimately connects with dewatered portions of the San Pedro River. In the proposed rule we included Hot Springs Canyon from its confluence with Bass Canyon downstream for 19.0 km (11.8 mi). In the final rule, we are reducing the portion of Hot Springs Canyon included within critical habitat to that area from its confluence with Bass Canyon downstream for approximately 9.3 km (5.8 mi).

Fossil Creek.

We received several comments and new information indicating that the best habitat for the species in Fossil Creek occurs above the newly constructed barrier at Township 11

1/2

North, Range 7 East, section 29. The portions of Fossil Creek above the barrier have been in use as a translocation site for spikedace beginning in 2008. Although there was limited success with the translocation initially, surveys in August 2011 (Crowder, 2011, pers. comm.) located numerous spikedace within Fossil Creek. While it would be premature to call the translocation a success, the persistence of spikedace indicates that it is suitable, and this area meets the definition of critical habitat for spikedace and loach minnow. For this reason, we are adjusting the area included within Fossil Creek to include the portions upstream of the barrier to the old Fossil Diversion Dam at Township 12 North, Range 7 East, section 14. The area incorporated in this stream segment will increase from 7.5 km (4.8 mi) to 22.2 km (13.8 mi).

In total, the areas designated as critical habitat for both species were reduced as compared to the revised proposed rule. For spikedace, the area included within the designation was reduced by 155 km (96 mi). For loach minnow, the area included within the designation was reduced by 160 km (99 mi). Portions of this are attributable to the changes noted above, and portions to changes made under the Exclusions section. The bulk of the reduced mileage can be attributed to exclusions on Eagle Creek and the San Pedro River and, to a lesser extent, on the Gila River.

Critical Habitat Background

Critical habitat is defined in section 3 of the Act as:

(1) The specific areas within the geographical area occupied by the species, at the time it is listed in accordance with the Act, on which are found those physical or biological features

(a) Essential to the conservation of the species and

(b) Which may require special management considerations or protection; and

(2) Specific areas outside the geographical area occupied by the species at the time it is listed, upon a determination that such areas are essential for the conservation of the species.

Conservation, as defined under section 3 of the Act, means to use and the use of all methods and procedures that are necessary to bring an endangered or threatened species to the point at which the measures provided pursuant to the Act are no longer necessary. Such methods and procedures include, but are not limited to, all activities associated with scientific resources management such as research, census, law enforcement, habitat acquisition and maintenance, propagation, live trapping, and transplantation, and, in the extraordinary case where population pressures within a given ecosystem cannot be otherwise relieved, may include regulated taking.

Critical habitat receives protection under section 7 of the Act through the requirement that Federal agencies insure, in consultation with the Service, that any action they authorize, fund, or carry out is not likely to result in the destruction or adverse modification of critical habitat. The designation of critical habitat does not affect land ownership or establish a refuge, wilderness, reserve, preserve, or other conservation area. Such designation does not allow the government or public to access private lands. Such designation does not require implementation of restoration, recovery, or enhancement measures by non-Federal landowners. Where a landowner seeks or requests Federal agency funding or authorization for an action that may affect a listed species or critical habitat, the consultation requirements of section 7(a)(2) of the Act would apply, but even in the event of a destruction or adverse modification finding, the obligation of the Federal action agency and the landowner is not to restore or recover the species, but to implement reasonable and prudent alternatives to avoid destruction or adverse modification of critical habitat.

Under the first prong of the Act's definition of critical habitat, areas within the geographical area occupied by the species at the time it was listed are included in a critical habitat designation if they contain physical or biological features (1) which are essential to the conservation of the species and (2) which may require special management considerations or protection. For these areas, the critical habitat designations identify, to the extent known using the best scientific and commercial data available, those physical or biological features that are essential to the conservation of the species (such as space, food, cover, and protected habitat). In identifying those physical and biological features within an area, we focus on the principal biological or physical constituent elements (PCEs such as roost sites, nesting grounds, seasonal wetlands, water quality, tide, soil type) that are essential to the conservation of the species. PCEs are the elements of physical or biological features that, when laid out in the appropriate quantity and spatial arrangement to provide for a species' life-history processes, are essential to the conservation of the species.

Under the second prong of the Act's definition of critical habitat, we can designate critical habitat in areas outside the geographical area occupied by the species at the time it is listed, upon a determination that such areas are essential for the conservation of the species. For example, an area currently occupied by the species but that was not occupied at the time of listing may be essential to the conservation of the species and may be included in the critical habitat designation. We designate critical habitat in areas outside the geographical area occupied by a species only when a designation limited to its range would be inadequate to ensure the conservation of the species.

Section 4 of the Act requires that we designate critical habitat on the basis of the best scientific and commercial data available. Further, our Policy on Information Standards Under the Endangered Species Act (published in the

Federal Register

on July 1, 1994 (59 FR 34271)), the Information Quality Act (section 515 of the Treasury and General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)), and our associated Information Quality Guidelines, provide criteria, establish procedures, and provide guidance to ensure that our decisions are based on the best scientific data available. They require our biologists, to the extent consistent with the Act and with the use of the best scientific data available, to use primary and original sources of information as the basis for recommendations to designate critical habitat.

When we are determining which areas should be designated as critical habitat, our primary source of information is generally the information developed during the listing process for the species. Additional information sources may include the recovery plan for the species, articles in peer-reviewed journals, conservation plans developed by States and counties, scientific status surveys and studies, biological assessments, or other unpublished materials and expert opinion or personal knowledge.

The location and suitability of habitat changes and species may move from one area to another over time. Climate change will be a particular challenge for biodiversity because the interaction of additional stressors associated with climate change and current stressors may push species beyond their ability to survive (Lovejoy 2005, pp. 325-326). The synergistic implications of climate change and habitat fragmentation are the most threatening facet of climate change for biodiversity (Hannah

et al.

2005, p. 4). Current climate change predictions for terrestrial areas in the Northern Hemisphere indicate warmer air temperatures, more intense precipitation events, and increased summer continental drying (Field

et al.

1999, pp. 1-3; Hayhoe

et al.

2004, p. 12422; Cayan

et al.

2005, p. 6; IPCC 2007b, p. 1181). Climate change may lead to increased frequency and duration of severe storms and droughts (Golladay

et al.

2004, p. 504; McLaughlin

et al.

2002, p. 6074; Cook

et al.

2004, p. 1015. Generally, the outlook presented for the Southwest predicts warmer, drier, drought-like conditions (Seager

et al.

2007, p. 1181; Hoerling and Eischeid 2007, p. 19), and a decline in water resources with or without climate change will be a significant factor in the compromised watersheds of the desert southwest.

Habitat is dynamic, or frequently changing, and species may move from one area to another over time. We recognize that critical habitat designated at a particular point in time may not include all of the habitat areas that we may later determine are necessary for the recovery of the species. For these reasons, a critical habitat designation does not signal that habitat outside the designated area is unimportant or may not be required for recovery of the species. Areas that are important to the conservation of the species, both inside and outside the critical habitat designations, will continue to be subject to: (1) Conservation actions

implemented under section 7(a)(1) of the Act, (2) regulatory protections afforded by the requirement in section 7(a)(2) of the Act for Federal agencies to insure their actions are not likely to jeopardize the continued existence of any endangered or threatened species, and (3) the prohibitions of section 9 of the Act if actions occurring in these areas may affect the species. Federally funded or permitted projects affecting listed species outside their designated critical habitat areas may still result in jeopardy findings in some cases. These protections and conservation tools will continue to contribute to recovery of this species. Similarly, critical habitat designations made on the basis of the best available information at the time of designation will not control the direction and substance of future recovery plans, habitat conservation plans (HCPs), or other species conservation planning efforts if new information available at the time of these planning efforts calls for a different outcome.

Occupied Versus Unoccupied Areas

We include as occupied those areas that were identified as occupied for each species in the original listing documents, as well as any additional areas determined to be occupied after 1986. Our reasoning for including these additional areas (post-1986) is that they were likely occupied at the time of the original listings, but had not been detected in surveys. In summary, there are three reasons why a stream segment is considered occupied at the time of listing: (1) The stream segment was occupied in the 1986 listing document; or (2) the fish were found subsequently to 1986; and (3) the post-1986 stream segment is between two occupied, but separated, stream segments.

Several factors may influence whether or not spikedace or loach minnow were detected in a given survey, and at what level. In some instances, survey efforts may have been minimal or absent for a given area. Once a species is listed, awareness of the species is heightened for wildlife and land managers, and survey efforts are often increased or expanded to include areas where they might be present. Moreover, spikedace and loach minnow are small-bodied fish that can be difficult to detect when in low numbers. This may be partially responsible for the lack of determinations over a 44-year period on Eagle Creek for loach minnow, for example. Finally, capture efficiencies for seining of fish are low, with some research indicating that capture efficiency of a seine haul averages 49 percent (Dewey and Holland-Bartels 1997, p. 101). This means that 51 percent of the fish present may not be captured. It should be noted that various factors can affect seining efficiency, and that most surveys involve more than one seine haul. However, if a species is present in low numbers, as is common for spikedace and loach minnow, the likelihood of catching them at the low capture efficiencies associated with seining is low. Loach minnow are likely to be more difficult to detect due to their having a reduced gas bladder. They are typically restricted to bottom-dwelling habitat, swimming in only brief movements, which may further reduce the likelihood of its being collected in a seine. We believe a combination of these factors to be responsible for the lack of detections over a 44 year period on Eagle Creek for loach minnow, as described above.

In some instances, areas were known to have been occupied by one or both species prior to listing, but were not described as occupied in the listing document based on the limited data available. Subsequent detections after listing in 1986 have caused us to reconsider the occupancy status of some streams. For example, we were aware of one loach minnow record for Dry Blue Creek from 1948 up until listing, but did not include Dry Blue Creek as occupied at listing in 1986 based on this record. Subsequent positive survey records in the late 1990s have caused us to reconsider this area. As a result, in this designation, we consider Dry Blue Creek to be occupied by loach minnow at the time of listing. Similarly, Eagle Creek had one record of loach minnow from 1950, but was not included as occupied at listing in 1986. Loach minnow were subsequently detected again in the 1990s, and it is therefore considered occupied at the time of listing within this designation.

In every case, areas discovered to be occupied after 1986 are connected, or historically were connected, to occupied areas. For example, the Black River complex was not known to be occupied until 1996; however, it is connected, albeit over long distances, to the White River, which is currently occupied, and the Salt River, which was historically occupied. Dry Blue Creek, described above, is connected to the occupied Blue River. Eagle Creek is a tributary to the Gila River, and at one time perennial flows would have connected this population to those in the upper portions of the Gila River in New Mexico. It is therefore logical to conclude that these areas had been occupied since listing, although possibly at low numbers that were difficult to detect.

Because areas determined to be occupied after 1986 are or were connected to occupied areas, the survey efforts for the species have been less than thorough, and because both species are difficult to detect in low numbers, we anticipate that, although occupancy was not determined in some areas until post-1986, the species were likely present at listing in 1986 in these areas, but not discovered until after listing.

Given that spikedace and loach minnow are small-bodied fish that can be difficult to detect when in low numbers, we also consider those areas included in this designation to be essential to the conservation of the species.

Physical and Biological Features

Under the Act and its implementing regulations, we are required to identify the physical and biological features (PBFs) essential to the conservation of spikedace and loach minnow in areas occupied at the time of listing, focusing on the features' primary constituent elements (PCEs). We consider PCEs to be the elements of physical and biological features that, when laid out in the appropriate quantity and spatial arrangement to provide for a species' life-history processes, are essential to the conservation of the species. We outline the appropriate quantities and spatial arrangements of the elements in the Physical and Biological Features (PBFs) section of the October 28, 2010, proposed rule. For example, spawning substrate would be considered an essential feature, while the specific composition (sand, gravel, and cobble) and level of embeddedness are the elements (PCEs) of that feature.

In accordance with section 3(5)(A)(i) and 4(b)(1)(A) of the Act and regulations at 50 CFR 424.12, in determining which areas within the geographical area occupied by the species at the time of listing to designate as critical habitat, we consider the PBFs essential to the conservation of the species and which may require special management considerations or protection. These include, but are not limited to:

(1) Space for individual and population growth and for normal behavior;

(2) Food, water, air, light, minerals, or other nutritional or physiological requirements;

(3) Cover or shelter;

(4) Sites for breeding, reproduction, or rearing (or development) of offspring; and

(5) Habitats that are protected from disturbance or are representative of the historical, geographical, and ecological distributions of a species.

We derive the specific PBFs required for spikedace and loach minnow from studies of their habitat, ecology, and life history as described in the Critical Habitat section of the proposed rule to designate critical habitat published in the

Federal Register

on October 28, 2010, and in the information presented below. Additional information can be found in the final listing rule published in the

Federal Register

on July 1, 1986 (spikedace; 51 FR 23769) and October 28, 1986 (loach minnow; 51 FR 39468), and the recovery plans for each of the species (Service 1991a, 1991b). Below, we provide a discussion of the physical and biological features that are essential to the conservation of the spikedace and loach minnows:

Space for Individual and Population Growth and for Normal Behavior

Spikedace

Microhabitats.

Habitat occupied by spikedace can be broken down into smaller, specialized habitats called microhabitats. These microhabitats vary by stream, by season, and by species' life stage. Studies on habitat use have been completed on the Gila River in New Mexico, and the Verde River and Aravaipa Creek in Arizona. Generally, spikedace occupy moderate to large perennial streams at low elevations over substrates (river bottom material) of sand, gravel, and cobble (Barber and Minckley 1966, p. 31; Propst

et al.

1986, pp. 3, 12; Rinne and Kroeger 1988, p. 1). Occupied streams are typically of low gradient (Barber

et al.

1970, p. 10; Rinne and Kroeger 1988, p. 2; Rinne 1991, pp. 8-12; Rinne and Stefferud 1996, p. 17), and less than 1 meter (m) (3.28 feet (ft)) in depth (Propst

et al.

1986, p. 41; Minckley and Marsh 2009, p. 155).

Larval spikedace occur most frequently in slow-velocity water near stream margins or along pool edges. Most larvae are found over sand substrates. Juvenile spikedace tend to be found over a greater range of water velocities than larvae, but still in shallow areas. Juvenile spikedace occupy areas with a gravel or sand substrate, although some have been found over cobble substrates as well. Larvae and juveniles may occasionally be found in quiet pools or backwaters (

e.g.,

pools that are connected with, but out of, the main river channel) (Sublette

et al.

1990, p. 138).

Adult spikedace occur in the widest range of flow velocities. They are typically associated with shear zones (areas within a stream where more rapidly flowing water abuts water moving at slower velocities), downstream of sand bars, and in eddies or small whirlpools along downstream margins of riffles (those shallow portions of the stream with rougher, choppy water). Adult spikedace are found in shallow water over predominantly gravel-dominated substrates (Propst

et al.

1986, p. 40; Rinne 1991, pp. 8-12; Rinne and Stefferud 1997, p. 21; Rinne and Deacon 2000, p. 106; Rinne 2001, p. 68), but also over cobble and sand substrates (Minckley and Marsh 2009, p. 155; Rinne and Kroeger 1988, p. 3; Sublette

et al.

1990, p. 138).

In addition to substrate type, the amount of embeddedness (filling in of spaces by fine sediments) is also important to spikedace. Spikedace more commonly occur in areas with low to moderate amounts of fine sediment and substrate embeddedness, which is important for the healthy development of eggs. Spawning has been observed in areas with sand and gravel beds and not in areas where fine materials smaller than sand coats the sand or gravel substrate. Additionally, low to moderate amounts of fine sediments ensure that eggs remain well-oxygenated and will not suffocate due to sediment deposition (Propst

et al.

1986, p. 40). Water temperatures of occupied spikedace habitat vary with time of year.

Water temperatures have been recorded at Aravaipa Creek, and on the Gila River in the Forks area and at the Cliff-Gila Valley. Water temperatures of occupied spikedace habitat vary with time of year. Summer water temperatures were between 19.3 degrees Celsius (°C) (66.7 degrees Fahrenheit (°F)) (Gila River, Forks Area) and 27 °C (80.6 °F) (Aravaipa Creek). Winter water temperatures ranged between 8.9 °C (48.0 °F) at Aravaipa Creek and 11.7 °C (53.1 °F) in the Cliff-Gila Valley (Barber and Minckley 1966, p. 316; Barber

et al.

1970, p

This text is long and has been trimmed here. Open the source document for the complete record.