Endangered and Threatened Wildlife and Plants; Proposed Endangered Status for the Cowhead Lake Tui Chub

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018--AE85

Endangered and Threatened Wildlife and Plants; Proposed

Endangered Status for the Cowhead Lake Tui Chub

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: The U.S. Fish and Wildlife Service (Service) proposes to

determine the Cowhead Lake tui chub (Gila bicolor vaccaceps), to be an

endangered species under the authority of the Endangered Species Act of

1973, as amended (Act). The Cowhead Lake tui chub is a fish that is

found only in Cowhead Slough and connected ditches within the bed of

Cowhead Lake in extreme northeastern Modoc County, California. This

subspecies is threatened throughout its range by a variety of human

impacts, including the dewatering of Cowhead Lake, livestock grazing,

agricultural activities, and by random naturally occurring events. This

proposal, if made final, would implement Federal protection provided by

the Act. The Service seeks data and comments from the public on this

proposal.

DATES: Comments from all interested parties must be received by May 29,

1998. Public hearing requests must be received by May 14, 1998.

ADDRESSES: Comments and materials concerning this proposal should be

sent to the Field Supervisor, Sacramento Fish and Wildlife Service

Office, U.S. Fish and Wildlife Service, 3310 El Camino Avenue, Suite

130, Sacramento, California 95821-6340. Comments and materials received

will be available for public inspection, by appointment, during normal

business hours at the above address.

FOR FURTHER INFORMATION CONTACT: Mr. Wayne S. White, Field Supervisor,

at the above address (telephone 916/979-2710).

SUPPLEMENTARY INFORMATION:

Background

. Fish and Wildlife Service, 3310 El Camino Avenue, Suite

130, Sacramento, California 95821-6340. Comments and materials received

will be available for public inspection, by appointment, during normal

business hours at the above address.

FOR FURTHER INFORMATION CONTACT: Mr. Wayne S. White, Field Supervisor,

at the above address (telephone 916/979-2710).

SUPPLEMENTARY INFORMATION:

Background

The Cowhead Lake tui chub was first recognized as a distinct

subspecies by Hubbs and Miller (1948) and was first described by Bills

and Bond (1980). The following morphological description is taken from

Bills and Bond (1980) and Moyle et al. (1989). The Cowhead Lake tui

chub is a small fish in the minnow family (Cyprinidae) approximately

85-115 millimeters (3-4.5 inches) from the nose to the middle of the

tail and is distinguished from the other subspecies of tui chub by the

number of gill rakers (bony projections in the gills). Coloration is

silver like other subspecies of tui chub, except for a dark lateral

stripe and dark speckles scattered on the cheek, operculum (area behind

the eye) and lower body. The pectoral fins usually exhibit a row of

melanophores (cells containing dark pigment) along the anterior rays

and a few specimens have exhibited a concentration of pigment on the

pelvic and anal fins. There have been no formal studies on the life

history or habitat of the Cowhead Lake tui chub. The following

information refers to tui chubs in general and is taken from Moyle

and lower body. The pectoral fins usually exhibit a row of

melanophores (cells containing dark pigment) along the anterior rays

and a few specimens have exhibited a concentration of pigment on the

pelvic and anal fins. There have been no formal studies on the life

history or habitat of the Cowhead Lake tui chub. The following

information refers to tui chubs in general and is taken from Moyle

(1976).

Tui chubs occur in a wide variety of habitats, most commonly in the

weedy shallows of lakes and quiet waters in sluggish rivers. They do

well in a wide variety of water conditions from warm to cold, and clear

to eutrophic. In the fall they seek out deeper water and may spend

winters in a semi-dormant state on the bottom of lakes. Tui chubs are

opportunistic omnivores concentrating on invertebrates associated with

bottom or aquatic plants (i.e., clams, insect larvae, insects,

crayfish) as well as algae and plant material. Tui chub usually spawn

from late April to late June; eggs adhere to plants or the bottom and

hatch in 9 days. In large deep lakes, tui chubs tend to form large

schools in shallow water frequently associated with beds of aquatic

vegetation. In shallow lakes, with heavy aquatic growth, schooling is

less noticeable. Tui chubs tend to disperse amongst the vegetation

presumably as protection from predators. Tui chubs appear to be able to

adapt to the severe long and short-term climatic fluctuations

characteristic of the interior basins where they are most common. The

family Cyprinidae in general has been successful because they have a

well-developed sense of hearing, release a fear scent when injured (a

warning signal to others), have pharyngeal teeth (broader diet), and

exhibit high fecundity. Despite these advantages, many native minnows

are declining in numbers as their environment deteriorates beyond their

ability to cope with the changes or they are displaced by more

aggressive introduced species

because they have a

well-developed sense of hearing, release a fear scent when injured (a

warning signal to others), have pharyngeal teeth (broader diet), and

exhibit high fecundity. Despite these advantages, many native minnows

are declining in numbers as their environment deteriorates beyond their

ability to cope with the changes or they are displaced by more

aggressive introduced species.

Cowhead Lake tui chub are found in the vicinity of Cowhead Lake, a

Pleistocene lake in the extreme northeastern corner of Modoc County,

California, in an area known as the Modoc Plateau. The Modoc Plateau

consists of molten basalt that formed approximately 70 million years

ago (Young et al. 1988). The area is characterized by lava rims, upland

plateaus, lava flows and tubes, ancient pluvial lake beds and large-

volume springs, and shallow soils (Young et al. 1988). Volcanic rock is

porous, therefore, most of the rainfall percolates through into the

groundwater. Surface water is minimal, but rainfall and snowmelt in the

mountains feed the groundwater, which surfaces as springs. The habitat

type is sagebrush steppe, which is generally a treeless, shrub-

dominated community characterized by sagebrush (Artemesia species) with

perennial bunch grasses in the understory and some juniper pine (Young

et al. 1988). The area is characterized by cold, harsh winters, dry

summers, and low rainfall.

The lakebed of Cowhead Lake is approximately 1,100 hectares (2,700

acres) based on assessors maps (Modoc County, California, Jan. 1982),

with an elevation of 1,597 meters (5,241 feet). Historically, Cowhead

Lake and Cowhead Slough are thought to have been marsh habitat, based

on the soil type. In its natural state the lake's water levels were

probably variable. This habitat type would have retained and stored its

water, slowly discharging it via Cowhead Slough to Twelvemile Creek and

on into the Warner Basin (Roger Farschon, Bureau of Land Management

(BLM), pers. comm., 1997a)

orically, Cowhead

Lake and Cowhead Slough are thought to have been marsh habitat, based

on the soil type. In its natural state the lake's water levels were

probably variable. This habitat type would have retained and stored its

water, slowly discharging it via Cowhead Slough to Twelvemile Creek and

on into the Warner Basin (Roger Farschon, Bureau of Land Management

(BLM), pers. comm., 1997a). Cowhead Slough and Cowhead Lake are fed

mainly by snowmelt runoff and springs via Eightmile Creek and other

smaller tributaries from the Warner Mountains. There may also be

several faults at the upper end of the slough that provide subsurface

flow (Sato in litt. 1992). Historically the lake was probably shallow

and naturally dried up on occasion (Peter Moyle, University of

California, Davis, pers. comm., 1997). Approximately 40 percent of the

lakebed occurs on private land and 60 percent of the lakebed has

unknown title based on a title search done in 1997 (Modoc County Title

Co. in litt. 1997). The lake went dry sometime in the 1930's. Since the

drought ended, and continuing up to the present day, the lake has been

mechanically pumped dry so that the lakebed could be used to grow hay.

There is a series of irrigation ditches, two reservoirs on nearby

creeks, and a mechanical pumping system, which

have modified the hydrology of the Cowhead basin.

Cowhead Lake tui chub were found in a spring and a reservoir

adjacent to Cowhead Lake (Miller 1939), in irrigation ditches within

Cowhead Lake (Sato in litt. 1993), and in Cowhead Slough (Moyle in

litt. 1974, Sato in litt. 1992 and 1993, Olson in litt. 1997, Jack

Williams, BLM, pers. comm., 1997). The entire current estimated range

of this species is approximately 5.4 kilometers (3.4 miles) of Cowhead

Slough and connected ditches within the bed of Cowhead Lake.

Approximately one half of the range is on public land managed by the

Bureau of Land Management (BLM)

Cowhead Slough (Moyle in

litt. 1974, Sato in litt. 1992 and 1993, Olson in litt. 1997, Jack

Williams, BLM, pers. comm., 1997). The entire current estimated range

of this species is approximately 5.4 kilometers (3.4 miles) of Cowhead

Slough and connected ditches within the bed of Cowhead Lake.

Approximately one half of the range is on public land managed by the

Bureau of Land Management (BLM). The other half of the range is on land

that has been managed by private ownership since the 1950's. However,

the Service has not been able to locate documentation of title in the

public records to support this assumption. This portion of the tui

chub's range will be referred to as private land in this proposed rule,

but the Service is not currently clear on the ownership of this portion

of the species range.

There are no population estimates available for the Cowhead Lake

tui chub. Surveys in the lake bed and adjacent springs and reservoirs

on private lands have been limited because access has been restricted.

Surveys on adjacent BLM land have focused on distribution and not

estimating population numbers.

Previous Federal Action

On December 30, 1982, the Service published a revised notice of

review for vertebrate wildlife in the Federal Register (47 FR 58454)

designating the Cowhead Lake tui chub as a category 2 candidate.

Category 2 was composed of taxa for which the Service had information

indicating that threatened or endangered status might be warranted, but

for which adequate data on biological vulnerability and threats were

not available to support issuance of listing proposals. As a result of

additional information obtained, the Service reclassified the Cowhead

Lake tui chub as a category 1 candidate in the November 21, 1991,

notice of review (56 FR 58804). The Cowhead Lake tui chub was included

as a candidate in the February 28, 1996 (61 FR 7596), and September 19,

1997 (62 FR 49398), notices of review

s were

not available to support issuance of listing proposals. As a result of

additional information obtained, the Service reclassified the Cowhead

Lake tui chub as a category 1 candidate in the November 21, 1991,

notice of review (56 FR 58804). The Cowhead Lake tui chub was included

as a candidate in the February 28, 1996 (61 FR 7596), and September 19,

1997 (62 FR 49398), notices of review.

The processing of this proposed rule conforms with the Service's

final listing priority guidance for fiscal year 1997, published in the

Federal Register on December 5, 1996 (61 FR 64475). In a Federal

Register notice published on October 23, 1997 (62 FR 55628), the

guidance was extended beyond fiscal year 1997. The fiscal year guidance

clarifies the order in which the Service will process rulemakings

following two related events: (1) The lifting on April 26, 1996, of the

moratorium on final listings imposed on April 10, 1995 (Pub. L. 104-6),

and (2) the restoration of significant funding for listing through

passage of the Omnibus Budget Reconciliation Act on April 26, 1996,

following severe funding constraints imposed by a number of continuing

resolutions between November 1995 and April 1996. Based on biological

considerations, this guidance establishes a ``multi-tiered approach

that assigns relative priorities, on a descending basis, to actions to

be carried out under section 4 of the Act'' (61 FR 64479). The guidance

calls for giving highest priority to handling emergency situations

(Tier 1) and second highest priority (Tier 2) to resolving the listing

status of the outstanding proposed listings. Tier 3 includes the

processing of new proposed listings for species facing high magnitude

threats. This proposed rule for the Cowhead Lake tui chub falls under

Tier 3. The guidance states that ``effective April 1, 1997, the Service

will concurrently undertake all of the activities presently included in

Tiers 1, 2, and 3'' (61 FR 64480)

the listing

status of the outstanding proposed listings. Tier 3 includes the

processing of new proposed listings for species facing high magnitude

threats. This proposed rule for the Cowhead Lake tui chub falls under

Tier 3. The guidance states that ``effective April 1, 1997, the Service

will concurrently undertake all of the activities presently included in

Tiers 1, 2, and 3'' (61 FR 64480). The Service has thus begun

implementing a more balanced listing program, including processing more

Tier 3 activities. The completion of this Tier 3 activity (a proposal

for a species with a listing priority of 3 (high-magnitude, imminent

threats)) follows those guidelines.

Summary of Factors Affecting the Species

Section 4 of the Act and regulations (50 CFR part 424) promulgated

to implement the listing provisions of the Act set forth the procedures

for adding species to the Federal lists. A species may be determined to

be endangered or threatened due to one or more of the five factors

described in section 4(a)(1). These factors and their application to

the Cowhead Lake tui chub are as follows:

A. The present or threatened destruction, modification, or

curtailment of its habitat or range. The historic range of the Cowhead

Lake tui chub is thought to be Cowhead Lake, when it retained water,

and the springs and low gradient portions of the creeks draining into

Cowhead Lake (P. Moyle, pers. comm., 1997; USDI 1997). The lake was

probably shallow and dried up naturally on occasion, periodically

confining Cowhead Lake tui chub to the streams and springs (P. Moyle,

pers. comm. 1997). The lakebed itself is 1,100 hectares (2,700 acres)

with a topographic gradient of 0 to 5 meters (0 to 16 feet) (based on

topographic measurements on a 1990 USGS 7.5 minute quadrangle map). The

surface flow of water is naturally highly variable in this volcanic,

high desert area. The amount of suitable aquatic habitat for this

species may vary from year to year based on the water supply

1997). The lakebed itself is 1,100 hectares (2,700 acres)

with a topographic gradient of 0 to 5 meters (0 to 16 feet) (based on

topographic measurements on a 1990 USGS 7.5 minute quadrangle map). The

surface flow of water is naturally highly variable in this volcanic,

high desert area. The amount of suitable aquatic habitat for this

species may vary from year to year based on the water supply. It is

unclear precisely what role the tributary springs and creeks currently

play in the life history of Cowhead Lake tui chub. It is also unknown

what the impact of flooding was when the lakebed was in its natural

state.

The diversion of water from Cowhead Lake has eliminated

approximately 98 percent of the Cowhead Lake tui chub's historical

range and is a threat to the Cowhead Lake tui chub. Before the turn of

the century a water diversion ditch (Peterson ditch) was built in the

Warner mountains west of Cowhead Lake, which diverts water from

Twelvemile Creek and possibly from Eightmile Creek into Surprise

Valley, southwest of Cowhead Lake (R. Farschon, pers. comm., 1997a).

Another ditch was built in the 1910's (Sato in litt. 1992) on the

Schadler property that appears to divert water from Peterson ditch into

Eightmile Creek. In the 1930's the lake went dry and ranchers started

growing hay in the lakebed. When the drought ended, the connection

between Cowhead Lake and Cowhead Slough was dredged so that the lake

would stay drained to permit continued hay production. Cowhead Slough

was dredged 1-1.5 meters (3-5 feet) deep from the lakebed north to the

edge of public BLM lands (R. Farschon, 1997a). In the 1960's a

privately owned reservoir was built on Eightmile Creek to allow

controlled irrigation to two pastures. This water is ultimately

collected in a ditch in the lakebed, which runs into Cowhead Slough.

Barrel Springs (2 miles to the southeast of Cowhead lake) and its

associated tributaries used to contribute water to Cowhead Lake until

its water flow was diverted for agricultural uses

he 1960's a

privately owned reservoir was built on Eightmile Creek to allow

controlled irrigation to two pastures. This water is ultimately

collected in a ditch in the lakebed, which runs into Cowhead Slough.

Barrel Springs (2 miles to the southeast of Cowhead lake) and its

associated tributaries used to contribute water to Cowhead Lake until

its water flow was diverted for agricultural uses. Currently the

seasonal waters from the Barrel Springs area drain to the northeast of

the lake and into Cowhead Slough. The lake usually holds some water

during the wet season before pumping begins in the spring. In the mid-

1980's and in 1997 there was enough water to fill the lake. Beginning

around April each year, water in Cowhead Lake is actively pumped into

Cowhead Slough and as a result no water remains in the lakebed outside

of the ditches. The historical shallow-water marsh habitat is now

maintained as irrigated pasture.

The current distribution of Cowhead Lake tui chub, based on recent

surveys (1992 to 1997), is in various pools in Cowhead Slough and in

connected ditches within the bed of Cowhead Lake from approximately 1

kilometer (0.5 mile) north of the confluence of Elevenmile Creek to the

irrigation ditch in the lakebed of Cowhead Lake, approximately 5.4

kilometers (3.4 miles). Cowhead Lake tui chub have been observed

feeding and hiding in filamentous mats of algae in the slough (Sato in

litt 1993). Mats of Ranunculus also appear to provide cover for young

of the year in the slough (Sato in litt 1993). Cowhead Slough consists

of a series of pools (95 percent) and riffles (5 percent) which wind

through a lava canyon approximately 50 meters (164 feet) wide and

approximately 6.4 kilometers (4 miles) long. The size of the water

course itself is far narrower than the canyon and varies according to

the amount of runoff and snowmelt each year. The slough ranges from 1-2

meters (4-6 feet) wide (Ken Sanchez, USFWS, pers

s

of a series of pools (95 percent) and riffles (5 percent) which wind

through a lava canyon approximately 50 meters (164 feet) wide and

approximately 6.4 kilometers (4 miles) long. The size of the water

course itself is far narrower than the canyon and varies according to

the amount of runoff and snowmelt each year. The slough ranges from 1-2

meters (4-6 feet) wide (Ken Sanchez, USFWS, pers. comm., 1997) to a

trickle, with large pools up to 10 meters (33 feet) wide, 50 meters

(164 feet) long and 1 meter (3 feet) deep (Moyle in litt 1974). In the

mid-1980's pools were reported to be up to 2 meters (6.5 feet) deep due

to heavy precipitation in those years (Sato in litt. 1992). Moyle et

al. (1989) reported the bottom of the channel as 80 percent mud, 5

percent sand, and 15 percent boulder/bedrock with abundant rooted and

floating vegetation, but little overhanging canopy cover. According to

Sato (in litt. 1993) the upper end of the slough above the pump on

private land has more riparian habitat (willows) and more perennial

water than the rest of slough. There is also a difference in topography

between the private and public sections of the slough. The private land

has a steeper gradient, more cobbles and boulders, deeper pools, and

more open water than the reaches on public lands. These factors may

account for why there appear to be more Cowhead Lake tui chub in

Cowhead Slough on the private land. It has also been hypothesized that

as the slough dries up annually, the fish move upstream to the more

perennial water.

The banks of Cowhead Slough contain mostly short-cropped annual

grasses with minimal riparian vegetation (Sato in litt. 1992). The

water has been reported as muddy and turbid during surveys from

possible erosion of the slough banks caused primarily by cattle grazing

and from drainage of ephemeral streams into the slough (Moyle in litt.

1974, Sato in litt. 1992)

to the more

perennial water.

The banks of Cowhead Slough contain mostly short-cropped annual

grasses with minimal riparian vegetation (Sato in litt. 1992). The

water has been reported as muddy and turbid during surveys from

possible erosion of the slough banks caused primarily by cattle grazing

and from drainage of ephemeral streams into the slough (Moyle in litt.

1974, Sato in litt. 1992). Cowhead Slough and the ditches in the

lakebed are within either public or private grazing allotments, which

are actively grazed (R. Farschon, pers. comm., 1997b). The lack of

riparian habitat can reduce the amount of water retained in the slough

later in the year (Sato in litt. 1993). The degradation of water

quality can reduce oxygen levels, visibility and prey abundance for the

Cowhead Lake tui chub.

Prior to being drained the lake is thought to have contained the

majority of the Cowhead Lake tui chub population. Currently the

population appears to be restricted to Cowhead Slough and connected

ditches within the lake bed, which have been severely altered from

their natural condition. The entire population occurs in one connected

drainage within a very confined area 5.4 kilometers (3.4 miles), and

there are no additional refugial populations. Protection of the habitat

within this very limited range is required to conserve the Cowhead Lake

tui chub. Further loss of habitat from agricultural modifications is a

threat to the continued existence of the Cowhead Lake tui chub.

B. Overutilization for commercial, recreational, scientific, or

educational purposes. The Cowhead Lake tui chub has not been documented

as a commercial or recreational fish species. It has been little

studied and there are only a handful of documented collections. This

factor is not considered a threat to the existence of the Cowhead Lake

tui chub.

C. Disease or predation. Aquatic snakes and birds are likely

predators of Cowhead Lake tui chub

ntific, or

educational purposes. The Cowhead Lake tui chub has not been documented

as a commercial or recreational fish species. It has been little

studied and there are only a handful of documented collections. This

factor is not considered a threat to the existence of the Cowhead Lake

tui chub.

C. Disease or predation. Aquatic snakes and birds are likely

predators of Cowhead Lake tui chub. This species is most vulnerable to

predation during drought periods when much of the drainage dries up and

Cowhead Lake tui chub are concentrated in smaller pools. The only other

species detected in Cowhead Lake tui chub habitat are speckled dace

(Rhinichthys osculus) and an occasional trout, which do not appear to

pose a threat to the Cowhead Lake tui chub. Introduction of nonnative

fish, game fish, or other tui chubs could harm the Cowhead Lake tui

chub through increased competition, predation, and hybridization. There

have been no documented instances of disease adversely affecting the

Cowhead Lake tui chub. If a disease were introduced, the tui chub

population would be at great risk because of its small size and

confined range.

D. The inadequacy of existing regulatory mechanisms. Currently

there are no regulatory mechanisms that specifically protect the

Cowhead Lake tui chub or its habitat. The current documented range of

the Cowhead Lake tui chub is approximately 50 percent on private land

and 50 percent on public land. It appears that the majority of the

population occurs on private land where there is more perennial water.

The Cowhead Lake tui chub is considered a species of special concern by

CDFG as Class 1: Endangered. This designation indicates that the

species meets the State definition to qualify for official listing, but

is not officially listed yet. The Federal status of the Cowhead Lake

tui chub is as a candidate species (see section on Previous Federal

Action)

and where there is more perennial water.

The Cowhead Lake tui chub is considered a species of special concern by

CDFG as Class 1: Endangered. This designation indicates that the

species meets the State definition to qualify for official listing, but

is not officially listed yet. The Federal status of the Cowhead Lake

tui chub is as a candidate species (see section on Previous Federal

Action). There is currently no regulatory authority vested in either

the State or Federal designations that offers protection or appropriate

management for this species. This lack of adequate regulatory

protection is a threat to the existence of the Cowhead Lake tui chub.

The National Environmental Policy Act (NEPA) and section 404 of the

Clean Water Act (CWA) represent the primary Federal laws that could

potentially afford some protection to listed species, however, neither

of these laws protect candidate species. The conversion of land to

agricultural uses that may adversely affect the Cowhead Lake tui chub

is generally unregulated at any level of government. For example, the

U.S. Army Corps of Engineers (Corps) has promulgated regulations that

exempt some farming, forestry, and maintenance activities from the

regulatory requirements of section 404 (33 CFR 323.4).

The California Environmental Quality Act (CEQA) offers some

opportunities to protect rare and endangered plants or animals, as well

as species that are eligible for listing but are not currently listed.

If a proposed project may significantly impact a species, it is

possible to require mitigation. However, this protection is at the

discretion of the lead agency involved and social and economic

considerations can override requirements for mitigation or protection.

Proposed revisions to CEQA guidelines, if made final, may weaken the

current protections for threatened, endangered and other sensitive

species

project may significantly impact a species, it is

possible to require mitigation. However, this protection is at the

discretion of the lead agency involved and social and economic

considerations can override requirements for mitigation or protection.

Proposed revisions to CEQA guidelines, if made final, may weaken the

current protections for threatened, endangered and other sensitive

species. Section 1603 of California Fish and Game Code authorizes the

California Department of Fish and Game (CDFG) to regulate streambed

alterations. Such alterations include any work that substantially

diverts, alters or obstructs the natural flow or substantially changes

the bed, channel or bank of any river, stream or lake. At this time,

the Service is not aware of any 1603 permit for the activities

occurring in Cowhead Lake and Cowhead Slough.

E. Other natural or manmade factors affecting its continued

existence. Pest control programs (i.e., USDA-APHIS grasshopper control

program) that

introduce pesticides into the drainage are a threat to the Cowhead Lake

tui chub. The water supply in this high desert habitat is low and

variable and naturally limits the amount of suitable habitat for the

Cowhead Lake tui chub. This natural condition offers fewer options for

refuge for Cowhead Lake tui chub in the event of drought, harsh winter

conditions or human-induced environmental impacts.

The entire population of Cowhead Lake tui chub occurs in less than

2 percent of its historical range and, therefore, is vulnerable to the

risks associated with small, restricted populations. Impacts to species

populations that can lead to extinction include: the loss or alteration

of essential elements (habitat, food), the introduction of limiting

factors into the environment (poison, predators), and catastrophic

random changes or environmental perturbations (extreme weather,

disease) (Gilpin and Soule 1986)

vulnerable to the

risks associated with small, restricted populations. Impacts to species

populations that can lead to extinction include: the loss or alteration

of essential elements (habitat, food), the introduction of limiting

factors into the environment (poison, predators), and catastrophic

random changes or environmental perturbations (extreme weather,

disease) (Gilpin and Soule 1986). Many extinctions are the result of a

severe reduction of population size by some deterministic event,

followed by a random natural event that extirpates the species. The

smaller a population is, the greater its vulnerability to stochastic

perturbations (Terbough and Winter 1980, Gilpin and Soule 1986, Shaffer

1987). The elements of risk that are amplified in very small

populations include: (1) The impact of high death rates or low births

rates; (2) the effects of genetic drift and inbreeding; and (3)

deterioration in environmental quality. When the number of individuals

in the sole population of a species or subspecies is sufficiently low,

the effects of inbreeding may result in the expression of deleterious

genes in the population (Gilpin 1987). Deleterious genes reduce

individual fitness in various ways, most typically as decreased

survivorship of young. Genetic drift in small populations decreases

genetic variation due to random changes in gene frequency from one

generation to the next.

This reduction of variability within a population limits the

ability of that population to adapt to environmental changes.

One scenario where loss of habitat may cause extinction is when the

species is a local endemic (because of their isolation and restricted

range) (Gilpin and Soule 1986). The Cowhead Lake tui chub is a local

endemic, which can be locally abundant, yet lives in a very restricted

area. Because the sole population is small and occurs in one single

drainage, it is extremely vulnerable to natural or human-made

environmental impacts

may cause extinction is when the

species is a local endemic (because of their isolation and restricted

range) (Gilpin and Soule 1986). The Cowhead Lake tui chub is a local

endemic, which can be locally abundant, yet lives in a very restricted

area. Because the sole population is small and occurs in one single

drainage, it is extremely vulnerable to natural or human-made

environmental impacts. There are no known populations of Cowhead Lake

tui chub outside of Cowhead Slough for recolonization if a catastrophic

event were to occur in Cowhead Slough. While the species still occurs

within its limited range, we do not know whether the population is

declining, how habitat conditions may be affecting the population, and

how the small population size may be affecting genetic and behavioral

stability. Based on the vulnerability of this small population in its

limited range, and the lack of any refugial populations or habitat, the

Service believes that threats to current occupied or potential habitat

and individuals put this species at risk of being extirpated.

The Service has carefully assessed the best scientific and

commercial information available regarding the present and future

threats faced by this species in determining this proposed rule. This

species is threatened throughout its range by a variety of human

impacts, including the dewatering of Cowhead Lake, livestock grazing,

agricultural activities, and by random naturally occurring events.

Based on this evaluation, the preferred action is to list Cowhead Lake

tui chub as endangered based on the risk of extinction throughout all

of its range. Critical habitat is not being proposed for this species

for reasons discussed in the ``Critical Habitat'' section of this

proposal.

Critical Habitat

1) The species is

threatened by taking or other human activity, and identification of

critical habitat can be expected to increase the degree of threat to

the species, or (2) such designation of critical habitat would not be

beneficial to the species. The Service determines that designation of

critical habitat for the Cowhead Lake tui chub is not prudent due to

lack of benefit to the species.

Critical habitat receives consideration under section 7 of the Act

with regard to actions carried out, authorized, or funded by a Federal

agency (see Available Conservation Measures section). As such,

designation of critical habitat may affect activities on Federal lands

and may affect activities on non-Federal lands where such a Federal

nexus exists. Under section 7 of the Act, Federal agencies are required

to ensure that their actions do not jeopardize the continued existence

of a species or result in destruction or adverse modification of

critical habitat. However, both jeopardizing the continued existence of

a species and adverse modification of critical habitat have similar

standards and thus similar thresholds for violation of section 7 of the

Act. In fact, biological opinions that conclude that a Federal agency

action is likely to adversely modify critical habitat but not

jeopardize the species for which the critical habitat has been

designated are extremely rare. Also, the designation of critical

habitat for the purpose of informing Federal agencies of the locations

of occupied Cowhead Lake tui chub habitat is not necessary because the

Service can inform Federal agencies through other means. For these

reasons, the designation of critical habitat for the Cowhead Lake tui

chub would provide no additional benefit to the species beyond that

conferred by listing, and therefore, such designation is not prudent.

Cowhead Lake tui chub has an extremely narrow distribution in one

small reach (5.4 kilometers (3.4 miles)) of Cowhead Slough

ice can inform Federal agencies through other means. For these

reasons, the designation of critical habitat for the Cowhead Lake tui

chub would provide no additional benefit to the species beyond that

conferred by listing, and therefore, such designation is not prudent.

Cowhead Lake tui chub has an extremely narrow distribution in one

small reach (5.4 kilometers (3.4 miles)) of Cowhead Slough. At the

present time, no other site is known to be occupied by or suitable for

this fish. However, the Service believes that a high level of awareness

already exists for this species due to numerous efforts since 1994,

between private and public entities, to develop and implement a

conservation agreement to conserve and protect this species ( J. Danna

in litt. 1994a and 1994b, J. Schadler in litt. 1994 and 1995, S. Stokke

in litt. 1997). In addition, the Cowhead Lake tui chub has been

included in the draft Recovery Plan for Warner Basin fishes and may

benefit to some degree from recovery actions specified for the listed

species in the plan (USDI 1997). The private

landowners at Cowhead Lake are aware of the Cowhead Lake tui chub's

presence and extremely limited habitat, as are the BLM managers and

others involved in management of the area. Therefore, designation of

critical habitat would provide no benefit with respect to notification.

In addition, given the species' narrow distribution and precarious

status, virtually any conceivable adverse effect to the species'

habitat would very likely jeopardize its continued existence.

Designation of critical habitat for Cowhead Lake tui chub would,

therefore, provide no benefit to the species apart from the protection

afforded by listing the fish as endangered.

Protection of the habitat of Cowhead Lake tui chub will be

addressed through the section 4 recovery process and the section 7

consultation process

ies'

habitat would very likely jeopardize its continued existence.

Designation of critical habitat for Cowhead Lake tui chub would,

therefore, provide no benefit to the species apart from the protection

afforded by listing the fish as endangered.

Protection of the habitat of Cowhead Lake tui chub will be

addressed through the section 4 recovery process and the section 7

consultation process. The Service believes that activities involving a

Federal action which may affect Cowhead Lake tui chub can be identified

without designating critical habitat by providing Federal agencies with

information on the locations of occupied habitats and information on

the kinds of activities which could affect the species. For the reasons

discussed above, the Service finds that the designation of critical

habitat for the Cowhead Lake tui chub is not prudent.

Available Conservation Measures

Conservation measures provided to species listed as endangered or

threatened under the Act include recognition, recovery actions,

requirements for Federal protection, and prohibitions against certain

practices. Recognition through listing results in conservation actions

by Federal, State, and local agencies, private organizations, and

individuals. The Act provides for possible land acquisition and

cooperation with the States and requires that recovery actions be

carried out for all listed species. The protection required of Federal

agencies and the prohibitions against certain activities are discussed,

in part, below.

The Cowhead Lake tui chub has been included in a draft Recovery

Plan for the threatened and rare native fishes of the Warner Basin and

Alkali (USDI 1997). The Cowhead Lake tui chub was included because it

is a rare native endemic that occurs within the Warner Basin that could

potentially benefit from recovery actions in the Warner Basin for the

other listed native fishes

ed,

in part, below.

The Cowhead Lake tui chub has been included in a draft Recovery

Plan for the threatened and rare native fishes of the Warner Basin and

Alkali (USDI 1997). The Cowhead Lake tui chub was included because it

is a rare native endemic that occurs within the Warner Basin that could

potentially benefit from recovery actions in the Warner Basin for the

other listed native fishes.

Section 7(a) of the Act, as amended, requires Federal agencies to

evaluate their actions with respect to any species that is proposed or

listed as endangered or threatened and with respect to its critical

habitat, if any is being designated. Regulations implementing this

interagency cooperation provision of the Act are codified at 50 CFR

part 402. Section 7(a)(4) of the Act requires Federal agencies to

confer with the Service on any action that is likely to jeopardize the

continued existence of a proposed species or result in destruction or

adverse modification of proposed critical habitat. If a species is

listed subsequently, section 7(a)(2) requires Federal agencies to

ensure that activities they authorize, fund, or carry out are not

likely to jeopardize the continued existence of such a species or to

destroy or adversely modify its critical habitat, if any is designated.

If a Federal action may affect a listed species or its critical

habitat, the responsible Federal agency must enter into formal

consultation with the Service. Approximately one-half of the only known

population of Cowhead Lake tui chub is on BLM-managed land including

grazing allotments within the range of this species. Grazing can

decrease water quality by removing vegetation on streambanks and

uplands, thereby increasing erosion and sedimentation, and by polluting

the water with waste products.

The Act and implementing regulations found at 50 CFR 17.21 set

forth a series of general prohibitions and exceptions that apply to all

endangered wildlife

uding

grazing allotments within the range of this species. Grazing can

decrease water quality by removing vegetation on streambanks and

uplands, thereby increasing erosion and sedimentation, and by polluting

the water with waste products.

The Act and implementing regulations found at 50 CFR 17.21 set

forth a series of general prohibitions and exceptions that apply to all

endangered wildlife. With respect to the Cowhead Lake tui chub, these

prohibitions, in part, make it illegal for any person subject to the

jurisdiction of the United States to take (including harass, harm,

pursue, hunt, shoot, wound, kill, trap, capture, collect, or attempt

any such conduct), import or export, transport in interstate or foreign

commerce in the course of commercial activity, or sell or offer for

sale in interstate or foreign commerce any listed species. It also is

illegal to possess, sell, deliver, carry, transport, or ship any such

wildlife that has been taken illegally. Certain exceptions apply to

agents of the Service and State conservation agencies.

Permits may be issued to carry out otherwise prohibited activities

involving endangered wildlife species under certain circumstances.

Regulations governing permits are at 50 CFR 17.22 and 17.23. Such

permits are available for scientific purposes, to enhance the

propagation or survival of the species, and for incidental take in

connection with otherwise lawful activities. Information collections

associated with these permits are approved under the Paperwork

Reduction Act, 44 U.S.C. 3501 et seq., and assigned Office of

Management and Budget clearance number 1018-0094. For additional

information concerning these permits and associated requirements, see

50 CFR 17.22. Requests for copies of the regulations regarding listed

species and inquiries about prohibitions and permits may be addressed

to: Regional Director, U.S. Fish and Wildlife Service, 911 NE 11th

Avenue, Portland, Oregon 97232-4181 (503/231-6241; FAX 503/231-6243)

Budget clearance number 1018-0094. For additional

information concerning these permits and associated requirements, see

50 CFR 17.22. Requests for copies of the regulations regarding listed

species and inquiries about prohibitions and permits may be addressed

to: Regional Director, U.S. Fish and Wildlife Service, 911 NE 11th

Avenue, Portland, Oregon 97232-4181 (503/231-6241; FAX 503/231-6243).

It is the policy of the Service, published in the Federal Register

on July 1, 1994 (59 FR 34272), to identify to the maximum extent

practicable at the time a species is listed those activities that would

or would not constitute a violation of section 9 of the Act if a

species is listed. The intent of this policy is to increase public

awareness of the effect of a proposed listing on proposed and ongoing

activities within a species' range. The Service believes that, based on

the best available information, the following actions will not result

in a violation of section 9, provided these actions are carried out in

accordance with any existing regulations and permit requirements:

(1) Possession of legally acquired Cowhead Lake tui chub;

(2) Actions that may affect Cowhead Lake tui chub which are

authorized, funded or carried out by a Federal agency, when the action

is conducted in accordance with an incidental take statement issued by

the Service pursuant to section 7 of the Act.

(3) Actions that may affect Cowhead Lake tui chub that are not

authorized, funded or carried out by a Federal agency, when the action

is conducted in accordance with an incidental take statement issued by

the Service pursuant to section 10(a)(1)(B) of the Act. Section

10(a)(1)(B) refers to Habitat Conservation Plans (HCP's) that are

negotiated after a species has been listed under Section 4 of the Act

and are designed to mitigate and minimize impacts to the species to the

greatest extent practicable

agency, when the action

is conducted in accordance with an incidental take statement issued by

the Service pursuant to section 10(a)(1)(B) of the Act. Section

10(a)(1)(B) refers to Habitat Conservation Plans (HCP's) that are

negotiated after a species has been listed under Section 4 of the Act

and are designed to mitigate and minimize impacts to the species to the

greatest extent practicable.

Activities that the Service believes could potentially harm the

Cowhead Lake tui chub and result in ``take'' include, but are not

limited to:

(1) Take of Cowhead Lake tui chub without a permit, which includes

harassing, harming, pursuing, hunting, shooting, wounding, killing,

trapping, capturing, or collecting, or attempting any of these actions;

(2) Possess, sell, deliver, carry, transport, or ship illegally

taken Cowhead Lake tui chub;

(3) Introduction of nonnative fish species that compete or

hybridize with, or prey on Cowhead Lake tui chub;

(4) Destruction or alteration of Cowhead Lake tui chub habitat by

dredging, channelization, diversion, instream vehicle operation or rock

removal, or other activities that result in the destruction or

significant degradation of cover, channel stability, substrate

composition, temperature, and corridors used by the species for

foraging, cover, and spawning;

(5) Discharges or dumping of toxic chemicals, silt, or other

pollutants into waters supporting Cowhead Lake tui chub that result in

death or injury of the species; and

rock

removal, or other activities that result in the destruction or

significant degradation of cover, channel stability, substrate

composition, temperature, and corridors used by the species for

foraging, cover, and spawning;

(5) Discharges or dumping of toxic chemicals, silt, or other

pollutants into waters supporting Cowhead Lake tui chub that result in

death or injury of the species; and

(6) Destruction or alteration of riparian or streamside habitat and

adjoining uplands of waters supporting Cowhead Lake tui chub by

grazing, mining, hydropower development, agriculture or other

developmental activities that result in destruction or significant

degradation of cover, channel stability, substrate composition,

temperature, and corridors used by the species for foraging, cover, and

spawning.

The term ``significant degradation of habitat'', as used in the

descriptions of activities above, is that amount of degradation which

causes ``take'' of Cowhead Lake tui chub. Not all of the activities

mentioned above will result in violation of section 9 of the Act; only

those activities which result in ``take'' of Cowhead Lake tui chub are

considered violations of section 9. Questions regarding whether

specific activities may constitute a violation of section 9 should be

directed to the Field Supervisor of the Services Sacramento Fish and

Wildlife Office (see ADDRESSES section). Requests for information on

permits should be addressed to the Assistant Regional Director,

Ecological Services, U.S. Fish and Wildlife Service, 911 NE. 11th

Avenue, Portland, Oregon 97232-4181 (503/231-6241; FAX 503/231-6243).

Public Comments Solicited

olation of section 9 should be

directed to the Field Supervisor of the Services Sacramento Fish and

Wildlife Office (see ADDRESSES section). Requests for information on

permits should be addressed to the Assistant Regional Director,

Ecological Services, U.S. Fish and Wildlife Service, 911 NE. 11th

Avenue, Portland, Oregon 97232-4181 (503/231-6241; FAX 503/231-6243).

Public Comments Solicited

The Service intends that any final action resulting from this

proposal will be as accurate and as effective as possible. Therefore,

comments or suggestions from the public, other concerned governmental

agencies, the scientific community, industry, or any other interested

parties concerning this proposed rule are hereby solicited. Comments

particularly are sought concerning:

(1) Biological, commercial trade, or other relevant data concerning

any threat (or lack thereof) to the Cowhead Lake tui chub;

(2) The location of any additional populations of the Cowhead Lake

tui chub and the reasons why any habitat should or should not be

determined to be critical habitat as provided by section 4 of the Act;

(3) Additional information concerning the range, distribution, and

population size of the Cowhead Lake tui chub;

(4) Any examples of take or vandalism of Cowhead Lake tui chub; and

(5) Current or planned activities in the subject area and their

possible impacts on the Cowhead Lake tui chub.

A final determination of whether to list this species will take

into consideration the comments and any additional information received

by the Service. Such communications may lead to a final decision

document that differs from this proposal.

The Act provides for one or more public hearings on this proposal,

if requested. Requests must be received within 45 days of the date of

publication of this proposal in the Federal Register. Such requests

must be made in writing and be addressed to the Field Supervisor,

Sacramento Field Office (see ADDRESSES section).

National Environmental Policy Act

ocument that differs from this proposal.

The Act provides for one or more public hearings on this proposal,

if requested. Requests must be received within 45 days of the date of

publication of this proposal in the Federal Register. Such requests

must be made in writing and be addressed to the Field Supervisor,

Sacramento Field Office (see ADDRESSES section).

National Environmental Policy Act

The Fish and Wildlife Service has determined that Environmental

Assessments or Environmental Impact Statements , as defined under the

authority of the National Environmental Policy Act of 1969, need not be

prepared in connection with regulations adopted pursuant to section

4(a) of the Endangered Species Act of 1973, as amended. A notice

outlining the Service's reasons for this determination was published in

the Federal Register on October 25, 1983 (48 FR 49244).

Required Determinations

This rule does not contain collections of information that require

approval by the Office of Management and Budget under 44 U.S.C. 3501 et

seq.

References Cited

A complete list of all references cited herein is available upon

request from the Field Supervisor, Sacramento Field Office (see

ADDRESSES section).

Author: The primary author of this proposed rule is Ann Chrisney,

Sacramento Field Office (see ADDRESSES section), telephone 916/979-

2725.

List of Subjects in 50 CFR Part 17

Endangered and threatened species, Exports, Imports, Reporting and

recordkeeping requirements, Transportation.

Proposed Regulation Promulgation

Accordingly, the Service hereby proposes to amend part 17,

subchapter B of chapter I, title 50 of the Code of Federal Regulations,

as set forth below:

PART 17--[AMENDED]

1. The authority citation for part 17 continues to read as follows:

Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C.

4201-4245; Pub. L. 99-625, 100 Stat. 3500, unless otherwise noted.

egulation Promulgation

Accordingly, the Service hereby proposes to amend part 17,

subchapter B of chapter I, title 50 of the Code of Federal Regulations,

as set forth below:

PART 17--[AMENDED]

1. The authority citation for part 17 continues to read as follows:

Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C.

4201-4245; Pub. L. 99-625, 100 Stat. 3500, unless otherwise noted.

2. Amend Sec. 17.11(h) by adding the following, in alphabetical

order under Fish, to the List of Endangered and Threatened Wildlife to

read as follows:

Sec. 17.11 Endangered and threatened wildlife.

* * * * *

(h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------

Species Vertebrate

-------------------------------------------------------- population where Critical Special

Historic range endangered or Status When listed habitat rules

Common name Scientific name threatened

--------------------------------------------------------------------------------------------------------------------------------------------------------

* * * * * * *

Fishes ....................

* * * * * * *

Chub, Cowhead Lake tui........... Gila bicolor U.S.A. (CA)........ Entire............. E ........... NA NA

vaccaceps.

* * * * * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------

Dated: March 17, 1998

Jamie Rappaport Clark,

Director, Fish and Wildlife Service.

[FR Doc. 98-8051 Filed 3-27-98; 8:45 am]

BILLING CODE 4310-55-P