Endangered and Threatened Species; Determination of Endangered Status for the Gulf of Maine Distinct Population Segment of Atlantic Salmon

Federal RegisterJun 19, 2009

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DEPARTMENT OF INTERIOR

Fish and Wildlife Service

50 CFR Part 17

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 224

[Docket No. 0808191116-9709-02]

RIN 0648-XJ93

Endangered and Threatened Species; Determination of Endangered Status for the Gulf of Maine Distinct Population Segment of Atlantic Salmon

AGENCY:

National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce; United States Fish and Wildlife Service (USFWS), Interior.

ACTION:

Final rule.

SUMMARY:

We (NMFS and USFWS, collectively referred to as the Services) have determined that naturally spawned and conservation hatchery populations of anadromous Atlantic salmon (

Salmo salar

) whose freshwater range occurs in the watersheds from the Androscoggin River northward along the Maine coast to the Dennys River, including those that were already listed in November 2000, constitute a distinct population segment (DPS) and hence a “species” for listing. We have determined that the Gulf of Maine (GOM) DPS warrants listing as endangered under the Endangered Species Act (ESA). Critical habitat for the GOM DPS will be designated in a subsequent

Federal Register

notice.

DATES:

This rule is effective July 20, 2009.

ADDRESSES:

Comments and materials received, as well as supporting scientific information used in the preparation of this rule, will be available for public inspection, by appointment, during normal business hours at: National Marine Fisheries Service, Northeast Regional Office, 55 Great Republic Drive, Gloucester MA 01930. An electronic copy of this final rule is available at:

http://www.nero.noaa.gov/prot_res/altsalmon/

. Public comments received can be viewed at

http://www.regulations.gov

FOR FURTHER INFORMATION CONTACT:

Rory Saunders, NMFS, at (207) 866-4049; Jessica Pruden, NMFS, at (978) 282-8482; Marta Nammack, NMFS, at (301) 713-1401; Lori Nordstrom, USFWS, at (207) 827-5938 ext. 13. Persons who use a Telecommunications device for the deaf (TDD) may call the Federal Information Relay Service (FIRS) at 1-800-877-8339, 24 hours a day, 7 days a week.

SUPPLEMENTARY INFORMATION:

Background

We issued a final rule listing the GOM DPS of Atlantic salmon as endangered on November 17, 2000 (65 FR 69469). The GOM DPS was defined as all naturally reproducing wild populations and those river-specific hatchery populations of Atlantic salmon having historical, river-specific characteristics found north of and including tributaries of the lower Kennebec River to, but not including, the mouth of the St. Croix River at the U.S.-Canada border. In the final rule listing the GOM DPS, we did not include fish that inhabit the mainstem and tributaries of the Penobscot River above the site of the former Bangor Dam, the upper Kennebec River, or the Androscoggin River within the GOM DPS (65 FR 69469; November 17, 2000).

In late 2003, we assembled the 2005 Biological Review Team (BRT) composed of biologists from the Maine Atlantic Salmon Commission (now the Maine Department of Marine Resources Bureau of Sea-run Fisheries and Habitat (MDMR)), the Penobscot Indian Nation, and both Services. The 2005 BRT was charged with reviewing and evaluating all relevant scientific information relating to the current DPS delineation (including a detailed genetic characterization of the Penobscot population and data relevant to the appropriateness of including the upper Kennebec and Androscoggin rivers as part of the DPS), determining the conservation status of the populations not included in GOM DPS listed in 2000, and assessing their relationship to the GOM DPS as it was listed in 2000. The findings of the 2005 BRT, which are detailed in the 2006 Status Review for Anadromous Atlantic Salmon in the United States (Fay

et al.

, 2006), addressed: the DPS delineation, including whether populations that were not included in the 2000 listing should be included in the GOM DPS; the extinction risks to the species; and the threats to the species. The 2006 Status Review (Fay

et al.

, 2006) underwent peer review by experts in the fields of Atlantic salmon biology and genetics to ensure that it was based on the best available science. Each peer reviewer independently affirmed the major conclusions presented in Fay

et al.

(2006).

Policies for Delineating Species Under the ESA

Section 3 of the ESA defines “species” as including “any subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature.” The term “distinct population segment” is not recognized in the scientific literature. Therefore, the Services adopted a joint policy for recognizing DPSs under the ESA (DPS Policy; 61 FR 4722) on February 7, 1996. The DPS policy requires the consideration of two elements when evaluating whether a vertebrate population segment may be considered a DPS under the ESA: (1) The discreteness of the population segment in relation to the remainder of the species or subspecies to which it belongs; and (2) the significance of the population segment to the species or subspecies to which it belongs.

A population segment of a vertebrate species may be considered discrete if it satisfies either one of the following conditions: (1) It is markedly separated from other populations of the same taxon (an organism or group of organisms) as a consequence of physical, physiological, ecological, or behavioral factors. Quantitative measures of genetic or morphological discontinuity may provide evidence of this separation; or (2) it is delimited by international governmental boundaries within which differences in control of exploitation, management of habitat, conservation status, or regulatory mechanisms exist that are significant in light of section 4(a)(1)(D) of the ESA (

i.e.

, inadequate regulatory mechanisms).

If a population segment is found to be discrete under one or more of the above conditions, its biological and ecological significance to the taxon to which it belongs is evaluated. This consideration may include, but is not limited to: (1) Persistence of the discrete population segment in an ecological setting unusual or unique for the taxon; (2) evidence that the loss of the discrete population segment would result in a significant gap in the range of a taxon; (3) evidence that the discrete population segment represents the only surviving natural occurrence of a taxon that may be more abundant elsewhere as an introduced population outside its historic range; and (4) evidence that the discrete population segment differs markedly from other populations of the species in its genetic characteristics.

Listing Determinations Under the ESA

The ESA defines an endangered species as one that is in danger of extinction throughout all or a significant portion of its range, and a threatened species as one that is likely to become endangered in the foreseeable future throughout all or a significant portion of its range (sections 3(6) and 3(20), respectively). The statute requires us to determine whether any species is endangered or threatened because of 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 (section 4(a)(1)(A-E)). We are to make this determination based solely on the best available scientific and commercial data available after conducting a review of the status of the species and taking into account any efforts being made by states or foreign governments to protect the species.

Atlantic Salmon Life History

Anadromous Atlantic salmon are a wide ranging species with a complex life history. The historic range of Atlantic salmon occurred on both sides of the North Atlantic: from Connecticut to Ungava Bay in the western Atlantic and from Portugal to Russia's White Sea in the Eastern Atlantic, including the Baltic Sea.

For Atlantic salmon in the United States, juveniles typically spend 2 years rearing in freshwater. Freshwater ecosystems provide spawning habitat and thermal refuge for adult Atlantic salmon; overwintering and rearing areas for eggs, fry, and parr; and migration corridors for smolts and adults (Bardonnet and Bagliniere, 2000). Adult Atlantic salmon typically spawn in early November. During spawning, the female uses its tail to scour or dig a series of nests in the gravel where the eggs are deposited; this series of nests is called a redd. The eggs remain in the redd until they hatch in late March or April. At this stage, they are referred to as alevin or sac fry. Alevins remain in the redd for about 6 more weeks and are nourished by their yolk sac until they emerge from the gravel in mid-May. At this time, they begin active feeding and are termed fry. Within days, the fry enter the parr stage, indicated by vertical bars (parr marks) on their sides that act as camouflage. Atlantic salmon parr are territorial; thus, most juvenile mortality is thought to be density dependent and mediated by habitat limitation (Gee

et al.

, 1978; Legault, 2005). In particular, suitable overwintering habitat may limit the abundance of large parr prior to smoltification (Cunjak

et al.

, 1998). Smoltification (the physiological and behavioral changes required for the transition to salt water) usually occurs at age 2 for most Atlantic salmon in Maine. The smolt emigration period is rather short and lasts only 2 to 3 weeks for each individual. During this brief emigration window, smolts must contend with rapidly changing osmoregulatory requirements (McCormick

et al.

, 1998) and predator assemblages (Mather, 1998). The freshwater stages in the life cycle of the Atlantic salmon have been well studied; however, much less information is available on Atlantic salmon at sea (Klemetsen

et al.

, 2003).

Gulf of Maine Atlantic salmon migrate vast distances in the open ocean to reach feeding areas in the Davis Strait between Labrador and Greenland, a distance over 4,000 km from their natal rivers (Danie

et al.

, 1984; Meister, 1984). During their time at sea, Atlantic salmon undergo a period of rapid growth until they reach maturity and return to their natal river. Most Atlantic salmon (about 90 percent) from the Gulf of Maine return after spending 2 winters at sea; usually less than ten percent return after spending 1 winter at sea; roughly one percent of returning salmon are either repeat spawners or have spent 3 winters at sea (3 sea winter, or 3SW salmon) (Baum, 1997).

In addition to anadromous Atlantic salmon, landlocked Atlantic salmon have been introduced to many lakes and rivers in Maine, though they are only native to four watersheds in the State: The Union, including Green Lake in Hancock County; the St. Croix, including West Grand Lake in Washington County; the Presumpscot, including Sebago Lake in Cumberland County; and the Penobscot, including Sebec Lake in Piscataquis County (Warner and Havey, 1985). There are certain lakes and rivers in Maine where landlocked salmon and anadromous salmon co-exist. Recent genetic surveys have confirmed that little genetic exchange occurs between these two life history types (Spidle

et al.

, 2003; NMFS unpublished data).

Delineation of the Gulf of Maine Distinct Population Segment

Fay

et al.

(2006) concluded that the DPS delineation that resulted in the 2000 listing designation (65 FR 69469; November 17, 2000) was largely appropriate, except in the case of large rivers that were excluded in the previous listing determination (Section 6.2.4 of Fay

et al.

, 2006). As described below in the analyses of discreteness and significance of the population segment, Fay

et al.

(2006) concluded that the salmon currently inhabiting the larger rivers (Androscoggin, Kennebec, and Penobscot) are genetically similar to the rivers included in the GOM DPS as listed in 2000 (Spidle

et al.

, 2003), have similar life history characteristics, and occur in the same zoogeographic region (section 6.3 of Fay

et al.

, 2006). Further, the salmon populations inhabiting the large and small rivers from the Androscoggin River northward to the Dennys River differ genetically and in important life history characteristics from Atlantic salmon in adjacent portions of Canada (Spidle

et al.

, 2003; Fay

et al.

, 2006). Thus, Fay

et al.

(2006) (section 6.3.1.4 and 6.3.2.4) concluded that this group of populations (population segment) met both the discreteness and significance criteria of the DPS Policy and, therefore should be considered a DPS. Fay

et al.

(2006) recommended that the new GOM DPS include all anadromous Atlantic salmon whose freshwater range occurs in the watersheds from the Androscoggin River northward along the Maine coast to the Dennys River, including all associated conservation hatchery populations used to supplement these natural populations; currently, such conservation hatchery populations are maintained at Green Lake National Fish Hatchery (GLNFH) and Craig Brook National Fish Hatchery (CBNFH).

Delineating Geographic Boundaries

Determining the precise boundary of the GOM DPS is difficult. In the case of the GOM DPS, we use a wide array of independent sources of information to make this determination. These sources of information include recent genetic analyses, life history, and zoogeography, among others. Recent genetic analyses, in particular, have clarified these distinctions, and we rely on them heavily in the following analysis. When using genetic data to make these delineations, it is important to note that extant populations must exist in order to make meaningful comparisons. In the case of determining the northern boundary of the GOM DPS, extant populations were used in genetic analyses and thus inform the determination. However, in the case of the determination of the southern boundary of the GOM DPS, many populations south of the Androscoggin are extirpated, and thus there are no genetic data available to make these

comparisons. For this reason we rely on additional information to delineate the southern boundary of the GOM DPS below.

We relied on genetic data to inform our determination on the northern terminus of the GOM DPS. At a broad scale, it is clear that there are substantial differences in genetic structure between U.S. and Canadian populations of Atlantic salmon (Spidle

et al.

, 2003). However, there are no genetic data on the wild salmon that once occurred in the St. Croix watershed along the U.S.-Canada border. As listed in 2000, the northern terminus of the GOM DPS was the U.S.-Canada border at the St. Croix River, but as described on page 54 of Fay

et al.

(2006), the best available science suggests that the St. Croix groups with other Canadian rivers. Genetic analyses found that salmon in the Dennys River are more similar to populations in the United States than to Canadian salmon populations that are geographically proximate to the Dennys (Spidle

et al.

, 2003). Therefore, we find that the northern terminus of the GOM DPS is the Dennys River watershed, rather than the St. Croix.

We determined the southern terminus of the GOM DPS to be the Androscoggin River based on zoogeography rather than genetics because there are extremely few Atlantic salmon in the rivers on which to base genetic analyses as one moves southward. Due to the combination of low numbers of Atlantic salmon in some rivers (

e.g.

, Androscoggin) and the complete extirpation of the native stock in other rivers to the south (

e.g.

, Merrimack), complete genetic data are not and may never be available for the Services to be able to genetically characterize these populations. In the absence of clear genetic data, we used ecological factors to define the southern boundary of the GOM DPS. The Androscoggin River lies within the Penobscot-Kennebec-Androscoggin Ecological Drainage Unit (EDU) (Olivero, 2003) and the Laurentian Mixed Forest Province (Bailey, 1995), which separates it from more southern rivers that were historically occupied by Atlantic salmon. EDUs are aggregations of watersheds with similar zoogeographic history, physiographic conditions, climatic characteristics, and basic geography (Olivero, 2003). The substantial changes in physiographic conditions south of the Androscoggin drainage are reflected in the southern terminus of both the Laurentian Mixed Forest Province and the Penobscot—Kennebec—Androscoggin EDU occurring in that area. Basin geography, climate, groundwater temperatures, hydrography, and zoogeographic differences between the Penobscot—Kennebec—Androscoggin EDU and the EDUs to the south (

e.g.

, Saco-Merrimack-Charles, Lower Connecticut, Middle Connecticut, and Upper Connecticut) likely had a strong effect upon Atlantic salmon ecology and production. These differences would influence the structure and function of aquatic ecosystems (Vannote

et al.

, 1980; Cushing

et al.

, 1983; Minshall

et al.

, 1983; Cummins

et al.

, 1984; Minshall

et al.

, 1985; Waters, 1995) and create a different environment for the development of local adaptations than rivers, such as the Saco and Merrimack, to the south.

In the proposed rule, we proposed to include the entire Androscoggin, Kennebec, and Penobscot Watersheds within the GOM DPS boundary. Some comments from the public appropriately highlighted several impassable falls that limited the upstream extent to which anadromous salmon inhabited the rivers of Maine. NMFS also evaluated historical occupancy at the watershed scale for the process of proposing critical habitat for the GOM DPS. There is also considerable information provided in the 2006 Status Review pertaining to impassable falls as well. We are, therefore, using these information sources (and others cited therein) to delimit the upstream extent of anadromy for GOM salmon in this final rule.

We have identified seven impassable falls that substantially limited the upstream extent of the freshwater range of GOM salmon. These include Rumford Falls in the town of Rumford on the Androscoggin River, Snow Falls in the town of West Paris on the Little Androscoggin River, Grand Falls in Township 3 Range 4 BKP WKR, on the Dead River in the Kennebec Basin; the un-named falls (impounded by Indian Pond Dam) immediately above the Kennebec River Gorge in the town of Indian Stream Township on the Kennebec River; Big Niagara Falls on Nesowadnehunk Stream in Township 3 Range 10 WELS in the Penobscot Basin; Grand Pitch Falls on Webster Brook in Trout Brook Township in the Penobscot Basin; and Grand Falls on the Passadumkeag River in Grand Falls Township in the Penobscot Basin (Table 1).

Table 1—Impassable Falls That Limit the Upstream Extent of the Freshwater Range of GOM Salmon

Name of falls

Town

River

Basin

Rumford Falls

Rumford

Androscoggin River

Androscoggin.

Snow Falls

West Paris

Little Androscoggin River

Androscoggin.

Grand Falls

Township 3 Range 4 BKP WKR

Dead River

Kennebec.

Un-named

Indian Stream Township

Kennebec River

Kennebec.

Big Niagara Falls

Township 3 Range 10 WELS

Nesowadnehunk Stream

Penobscot.

Grand Pitch

Trout Brook Township

Webster Brook

Penobscot.

Grand Falls

Grand Falls Township

Passadumkeag River

Penobscot.

As a result, we have modified the geographic boundaries of the freshwater range of GOM salmon in the Androscoggin, Kennebec, and Penobscot Basins in the following ways: all freshwater bodies in the Androscoggin Basin are included up to Rumford Falls on the Androscoggin River and up to Snow Falls on the Little Androscoggin River; all freshwater bodies in the Kennebec Basin are included up to Grand Falls on the Dead River and the unnamed falls (currently impounded by Indian Pond Dam) immediately above the Kennebec River Gorge; and all freshwater bodies in the Penobscot Basin are included up to Big Niagara Falls on Nesowadnehunk Stream, Grand Pitch on Webster Brook, and Grand Falls on the Passadumkeag River.

We recognize that many other potentially impassable waterfalls exist throughout the range of GOM salmon. While other impassable falls may exist throughout the range, we did not exclude any other areas (other than the areas above the seven falls mentioned above) for the following reasons: (1) Their occurrence is typically in headwater areas that preclude access from relatively small portions of a given watershed; (2) identifying every impassable falls is impractical given

current information; and (3) no other impassable falls were brought to our attention during the public comment period.

In addition, we recognize that within every watershed, there is an upstream extent of anadromy. However, it is impossible to define that specific point in every watershed. The upstream extent of anadromy is ultimately limited by the incremental narrowing of a given river or stream. While a stream may be too small for an adult salmon to swim up any further, juveniles may ascend further than that point in search of suitable rearing habitat. In fact, upstream movement of even fry can be quite substantial. As such, we include all the freshwater bodies as part of the freshwater range of GOM salmon unless above one of the impassable falls mentioned in the text above.

Discreteness and Significance of the GOM DPS

With respect to the “discreteness” of this population segment, section 6.3.1 of Fay

et al.

(2006) considered ecological, behavioral, and genetic factors under the first discreteness criterion of the DPS Policy to examine the degree to which it is separate from other Atlantic salmon populations. Gulf of Maine salmon are behaviorally and physiologically discrete from other members of the taxon because they return to their natal GOM rivers to spawn (a process called homing), which leads to the separation in stocks that has been observed between the Gulf of Maine and other segments of the taxon. River-specific adaptation is an important mechanism that allows anadromous salmon to occupy diverse environments throughout their range. River-specific adaptation is facilitated by homing and is characteristic of all other anadromous salmonids (Klemetsen

et al.

, 2003; Utter

et al.

, 2004). Baum and Spencer (1990) found that roughly 98 percent of all tagged salmon returned to their natal rivers to spawn. As described below, these strong homing tendencies have led to the formation and maintenance of river-specific adaptations for GOM salmon as well.

Ecologically, GOM salmon are discrete from other members of the taxon. The core of the riverine habitat of this population segment lies within the Penobscot-Kennebec-Androscoggin EDU (Olivero, 2003) and the Laurentian Mixed Forest Province (Bailey, 1995). These environmental conditions have shaped life history characteristics of GOM salmon. In particular, GOM salmon life history strategies are dominated by age 2 smolts and 2SW adults, whereas populations to the north of this population segment are generally dominated by age 3 or older smolts and 1SW adults (called grilse). Smolt age reflects growth rate (Klemetsen

et al.

, 2003), with faster growing parr emigrating as smolts earlier than slower growing ones (Metcalfe

et al.

, 1990). Smolt age is largely influenced by temperature (Symons, 1979; Forseth

et al.

, 2001) and can therefore be used to compare and contrast growing conditions across rivers (Metcalfe and Thorpe, 1990). For GOM populations, smolt ages are quite similar across rivers with naturally-reared (result of either wild spawning or fry stocking) returning adults predominantly emigrating at river age 2 (88 to 100 percent) with the remainder emigrating at river age 3 (Fay

et al.

, 2006). Smolt ages from naturally-reared returning adults in rivers south of the Penobscot-Kennebec-Androscoggin EDU are also dominated by river age 2 smolts with some emigrating at river age 3, but a substantial proportion of river age 1 smolts are also present (See Table 6.3.1.1 in Fay

et al.

, 2006).

The strongest evidence that GOM salmon are discrete from other members of the taxon is genetic. Fay

et al.

(2006) described genetic structure of this population segment and other stocks in detail in section 6.3.1.3. In summary, three primary genetic groups of North American populations (Spidle

et al.

, 2003; Spidle

et al.

, 2004; Verspoor

et al.

, 2005) are evident. These include the anadromous GOM populations (including salmon in the Kennebec and Penobscot Rivers) (Spidle

et al.

, 2003), non-anadromous Maine populations (Spidle

et al.

, 2003), and Canadian populations (Verspoor

et al.

, 2005). Because of these behavioral, physiological, ecological and genetic factors, we conclude that the GOM anadromous population is discrete from other Atlantic salmon populations under the provisions of the DPS Policy.

With respect to the “significance” of this population segment, Fay

et al.

(2006) found that there are three attributes which are described as evidence for “significance” in the DPS policy that are applicable to the GOM DPS (section 6.3.2 of Fay

et al.

, 2006). Fay

et al.

(2006) (section 6.3.2.1) concluded that this population segment has persisted in an ecological setting unusual or unique to the taxon for several reasons. First, GOM salmon live in and migrate through a unique marine environment. The marine migration corridor for GOM salmon begins in the GOM that is known for unique circulation patterns, thermal regimes, and predator assemblages (Townsend

et al.

, 2006). Gulf of Maine salmon undertake extremely long marine migrations to feeding grounds off the West Coast of Greenland because the riverine habitat they occupy is at the southern extreme of the current North American range. While such vast marine migrations are more common for stocks on the northeast side of the Atlantic, the combination of the long migration distances and the unique setting of the GOM, described above, make the oceanic life history of the GOM DPS quite different from those of other stocks (ICES, 2008). In addition, the core of the riverine habitat of this population segment lies within the Penobscot-Kennebec-Androscoggin EDU (Olivero, 2003) and the Laurentian Mixed Forest Province (Bailey, 1995). The importance of this setting is evidenced by the tremendous production potential of its juvenile nursery habitat that allows production of proportionately younger smolts than Canadian rivers to the north (Myers, 1986; Baum, 1997; Hutchings and Jones, 1998). Thus, the combination of the unique rearing conditions in the freshwater portion of its range combined with the unique marine migration corridor led Fay

et al.

(2006) to conclude that this population segment has persisted in an ecological setting unusual or unique to the taxon.

Fay

et al.

(2006) also concluded that the loss of this population segment would result in a significant gap or constriction in the range of the taxon (Section 6.3.2.2 of Fay

et al.

, 2006). The extirpation of this population segment would represent a significant range reduction for the entire taxon

Salmo salar

because this population segment represents the southernmost native Atlantic salmon population in the western Atlantic. The temperature regimes in these southern rivers made possible the tremendous growth and production potential which resulted in the historically very large populations in these areas. Historic attempts to enhance salmon populations (in GOM rivers) using Canadian-origin fish failed. This further illustrates the importance of conserving native, river-specific populations and the difficulties of restoration if they are lost.

Fay

et al.

(2006) concluded that this population segment differs markedly from other populations of the species in its genetic characteristics (Section 6.3.2.3 of Fay

et al.

, 2006). While genetic differences were used to examine the “discreteness” of this population segment, Fay

et al.

(2006) suggested that the “significance” of these observed genetic differences is that they provide evidence of local adaptation. That is, low returns of exogenous smolts (

i.e.

, Canadian-origin

smolts stocked in Maine) and lower survival of smolts from these Maine rivers stocked outside their native geographic range (

e.g.

, into the Merrimack River) indicate that this population segment is adapted to its native environment. Based on this information related to significance, Fay

et al.

(2006) concluded that this population segment is significant to the Atlantic salmon species, and therefore, qualifies as a DPS (the new GOM DPS) under the provisions of the DPS Policy.

Fay

et al.

(2006) (section 6.3.4) explicitly considered whether to include hatchery populations in the GOM DPS and concluded that all conservation hatchery populations (currently maintained at GLNFH and CBNFH) should be included in the GOM DPS. This determination was based on the fact that there is a low level of genetic divergence between conservation hatchery populations and the rest of the GOM DPS because: (1) The river-specific hatchery programs collect wild parr or sea-run adults annually (when possible) for inclusion into the broodstock programs; (2) broodstocks are used to stock fry and other life stages into the river of origin, and, in some instances, hatchery-origin individuals represent the primary origin of Atlantic salmon due to low adult returns; (3) there is little evidence of introgression from Canadian-origin populations; and (4) there is minimal introgression from aquaculture fish because of a rigorous genetic screening program in the hatchery. Because the level of divergence is minimal, in Section 6.3.4 Fay

et al.

(2006) suggested that hatchery populations should be considered part of the GOM DPS. However, Fay

et al.

(2006) also noted the dangers of reliance on hatcheries. In short, genetic risks from hatcheries include artificial selection, inbreeding depression, and outbreeding depression, in addition to other risks such as the potential for disease outbreaks, loss of funding, or other catastrophic failure at one or more hatcheries. The reader is directed to “Population Status of the GOM DPS” section of this final rule and Section 8.5.1 of Fay

et al.

(2006) for an in depth discussion of these risks.

For the reasons described in Section 6 of Fay

et al.

(2006), we conclude that the GOM DPS as described above warrants delineation as a DPS (

i.e.

, it is discrete and significant). Specifically, we conclude that the GOM DPS is comprised of all anadromous Atlantic salmon whose freshwater range occurs in the watersheds from the Androscoggin River northward along the Maine coast to the Dennys River, including all associated conservation hatchery populations used to supplement these natural populations; currently, such populations are maintained at GLNFH and CBNFH. We consider the conservation hatchery populations that are maintained at CBNFH and GLNFH essential for recovery of the GOM DPS because the hatchery populations contain a high proportion of the genetic diversity remaining in the GOM DPS (Bartron

et al.

, 2006). Excluded are those salmon raised in commercial hatcheries for aquaculture and landlocked salmon because they are genetically distinguishable from the GOM DPS. The marine range of the GOM DPS extends from the Gulf of Maine to feeding grounds off Greenland. The freshwater range of the GOM DPS includes all freshwater bodies in the watersheds from the Androscoggin to the Dennys, except those watersheds excluded because of natural barrier falls as described in the “Delineating Geographic Boundaries” section of this final rule. The most substantial difference between the GOM DPS as listed in 2000 and the GOM DPS described in this final rule is the inclusion of the majority of the Androscoggin, Kennebec, and Penobscot Basins as well as the associated conservation hatchery population at GLNFH.

Several rivers outside the range of the GOM DPS in Long Island Sound and Central New England contain Atlantic salmon (Fay

et al.

, 2006; section 6.4). The native Atlantic salmon of these areas south of the GOM DPS were extirpated in the 1800s (Fay

et al.

, 2006). Efforts to restore Atlantic salmon to these areas (

e.g.

, Connecticut, Merrimack, and Saco Rivers) involve stocking Atlantic salmon that were originally derived from the GOM DPS. Atlantic salmon whose freshwater range occurs outside the range of GOM DPS do not interbreed with salmon within the GOM DPS, are not considered a part of the GOM DPS, and are not protected under the ESA.

Population Status of the GOM DPS

In evaluating the status of Atlantic salmon, we considered four basic attributes that contribute to a viable population: abundance, productivity, genetic diversity, and spatial distribution. The importance of considering each of these factors is briefly described below. However, it is important to note that our ability to conduct such analyses for Atlantic salmon is often limited by the availability of sufficient data. It is also important to note that the most recent data available at the time of writing of this final rule was from 2007. We consider the U.S. Atlantic Salmon Assessment Committee (USASAC) reports to be the data of record with respect to Atlantic salmon counts. USASAC reports are generally not available until several weeks after their annual meeting in March. Thus, 2008 data are considered only preliminary at the time of writing this final rule.

Considering abundance levels of a given species is critical to evaluating extinction risks. All else being equal, small populations are at greater risk of extinction than larger populations because, generally, larger populations are better able to withstand the effects of environmental variation, genetic processes, demographic stochasticity, ecological feedback, and catastrophes (Shaffer, 1981).

Population growth rate (productivity) provides information regarding how a population is performing in the habitat it occupies. In evaluating extinction risks, we ideally measure average productivity at different life stages and estimates of variance to describe the level of uncertainty inherent in the measurements. An example of life stage-specific data could be smolt emigration estimates which represent: (a) The population's potential to increase or (b) the population's ability to weather periods of poor marine conditions. Measuring productivity rates over time is quite difficult and resource intensive. Therefore, simple measures such as spawner population size and replacement rates may be used to provide more rapid detection of changes in conditions affecting population growth rates.

For small populations, spatial distribution is important to reduce extinction risks from genetic risks and demographic stochasticity. A population's spatial distribution depends on habitat quality (including accessibility), population dynamics, and dispersal characteristics of individuals in the population. Analysis of spatial distribution focuses primarily on spawning group distribution (even though spatial distribution is important at all life stages) and connectivity of populations. Since freshwater habitat is often quite heterogeneous, spawning habitat may be distributed as discrete patches. Straying is an important component contributing to spatial distribution and, typically, straying rates are higher at smaller scales (

e.g.

, occurring within subpopulations rather than between populations (Quinn, 1997)).

Genetic diversity allows species to adapt to a variety of environments that provide for the needs of the species and

protects against short-term environmental change while also providing the raw genetic material necessary to survive long-term environmental change. Natural demographic and evolutionary processes (patterns of mutation, selection, drift, recombination, migration, etc.) are important to maintaining a species' genetic diversity.

The influence of hatcheries on the GOM DPS must be carefully considered in evaluating the status of the species. The influence of hatcheries can be both positive and negative; we describe these effects in some detail below in this section of this final rule. It is important, however, to first describe the general operation of conservation hatcheries in Maine.

The USFWS operates two hatcheries in support of Atlantic salmon recovery efforts in Maine. Together, Green Lake National Fish Hatchery (GLNFH) and Craig Brook National Fish Hatchery (CBNFH) raise and stock over 600,000 smolts and 3.5 million fry annually within the range of the GOM Atlantic salmon DPS. The primary focus of the conservation hatchery program for the GOM Atlantic salmon DPS is to conserve the genetic legacy of Atlantic salmon in Maine until habitats can support natural, self-sustaining populations (Bartron

et al.,

2006). As such, a great deal of consideration is given to broodstock collection, spawning protocols, genetic screening for aquaculture escapees, and other considerations as outlined by Bartron

et al.

(2006). The current program started in 1992, when a river-specific broodstock and stocking program was implemented for rivers in Maine (Bartron

et al.,

2006). This strategy complies with the North Atlantic Salmon Conservation Organization (NASCO) guidelines for stock rebuilding (USASAC, 2005). The stocking program was initiated for two reasons: (1) Runs were declining in every river in Maine, and numerous studies indicated that restocking efforts are more successful when the donor population comes from the river to be stocked (Moring

et al.,

1995); and (2) the numbers of returning adult Atlantic salmon to the rivers were very low, and artificial propagation had the potential to increase the number of juvenile fish in the river through fry and other early life stage stocking.

Current practices of fry, parr, and smolt stocking as well as recovery of parr for hatchery rearing are designed to ensure that river-specific brood stock is available for future production. Atlantic salmon from the Narraguagus, Pleasant, Sheepscot, Machias, East Machias, and Dennys populations are maintained at CBNFH in East Orland, Maine. These populations are augmented by annual collections of parr from their respective natal river; this program is described in detail by Bartron

et al.

(2006). Additionally, returning adult Atlantic salmon are trapped at the Veazie Dam on the Penobscot River throughout the duration of the run, transferred to CBNFH, and held until spawning in the fall of each year. In addition, domestic adults (

i.e.,

offspring of the sea-run adults representing all sea-run spawned families) from the Penobscot River are maintained at GLNFH in the event that insufficient sea-run adults return to the Veazie trap or in the event of a fish loss at CBNFH. Adult Atlantic salmon (with the exception of the Penobscot River) are maintained in one of six river-specific broodstock rooms at CBNFH. Within each broodstock room, adults are maintained separately by capture year. Capture year is defined as the year parr were collected from a river. Each capture year may represent one to two year classes. In addition, fully captive lines, or “pedigree lines,” are implemented when the recovery of parr from the river environment is expected to be too low to ensure future spawning stock is available (Bartron

et al.,

2006). Pedigree lines are established at the time of stocking, where a proportional representation of each family from a particular river-specific broodstock is retained in the hatchery while the rest of the fry are stocked into the river. If parr are recovered from the fry stocking for the pedigree lines, individuals are screened to determine origin and familial representation and are integrated into the pedigree line to maintain some component of natural selection while maintaining a broad representation of the genetic diversity observed in the broodstock.

The goals of the captive propagation program include maintenance of the unique genetic characteristics of each river-specific broodstock and maintenance of genetic diversity within each broodstock (Bartron

et al.,

2006). Evaluation of estimates of genetic diversity within captive populations, such as average heterozygosity, relatedness, and allelic richness are monitored within the hatchery broodstocks according to the CBNFH Broodstock Management Plan (Bartron

et al.,

2006). Estimates of allelic richness within each broodstock have thus far, revealed consistent estimates over the brief time series available (generally 1994 to 2004; Bartron

et al.,

2007). Information from genetic monitoring is used to evaluate management practices to reduce the potential for artificially reducing overall genetic diversity. Further details of annual genetic monitoring are described by Bartron

et al.

(2007).

The current low abundance of adult returns, integration of the majority of adult returns into the hatchery for the Penobscot, and recapture of parr from the wild for broodstock makes the wild and hatchery populations interwoven. In the following sections of this final rule, we describe the four population attributes of interest (abundance, productivity, spatial structure, and genetic diversity) and attempt to apply them first to the wild population and then discuss the impact the hatchery has on that attribute. For the reasons noted above, however, it is rarely possible to completely separate the wild and hatchery population in this analysis.

Abundance

The abundance of Atlantic salmon within the range of the GOM DPS has been generally declining since the 1800s (Fay

et al.,

2006). Data sets tracking adult abundance are not available throughout this entire time period; however, Fay

et al.

(2006) in Figure 7.3.1 present a comprehensive time series of adult returns to the GOM DPS dating back to 1967. It is important to note that contemporary abundance levels of Atlantic salmon within the GOM DPS are several orders of magnitude lower than historical abundance estimates. For example, Foster and Atkins (1869) estimated that roughly 100,000 adult salmon returned to the Penobscot River alone before the river was dammed, whereas contemporary estimates of abundance for the entire GOM DPS have rarely exceeded 5,000 individuals in any given year since 1967 (Fay

et al.,

2006).

Contemporary abundance estimates are informative in considering the conservation status of the GOM DPS today. After a period of population growth in the 1970s, adult returns of salmon in the GOM DPS have been steadily declining since the early 1980s and appear to have stabilized at low levels since 2000 (Figure 1). The population growth observed in the 1970s is likely attributable to favorable marine survival and increases in hatchery capacity, particularly at GLNFH, which was constructed in 1974. Marine survival remained relatively high throughout the 1980s, and salmon populations in the GOM DPS remained relatively stable until the early 1990s when marine survival rates decreased, leading to the declining trend in adult abundance observed in the early 1990s.

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Adult returns to the GOM DPS have been very low for many years and remain extremely low in terms of adult abundance in the wild. Further, the majority of all adults return to a single river, the Penobscot, which accounted for 91 percent of all adult returns to the GOM DPS in 2007 (Table 2). As illustrated by Table 3, of the 925 adult returns to the Penobscot in 2007, 802 were the result of smolt stocking and only the remaining 123 were naturally-reared. The term “naturally-reared” includes fish originating from natural spawning and hatchery fry (USASAC, 2008). Hatchery fry are included because hatchery fry are not marked; therefore, they cannot be distinguished from fish produced from natural spawning. Because of the extensive amount of fry stocking that takes place in an effort to recover the GOM DPS, it is likely that a substantial number of fish counted as naturally-reared were actually stocked as fry. The term “hatchery-origin” includes those fish stocked as either parr or smolt from either CBNFH or GLNFH.

The proportion of naturally reared fish that is attributed to fry stocking cannot be determined. Preliminary adult return data for 2008 (

http://www.maine.gov/dmr/searunfish/trapcounts.html

) indicated higher returns than in previous years, but remain well below conservation spawning escapement (CSE) goals that are widely used (

e.g.

, ICES, 2005) to describe the status of individual Atlantic salmon populations. When CSE goals are met, Atlantic salmon populations are generally self-sustaining. When CSE goals are not met (

i.e.

, less than 100 percent), populations are not reaching full potential, and this can be indicative of a population decline. For all rivers in Maine, current Atlantic salmon populations (including hatchery contributions) are well below CSE levels required to sustain themselves (Fay

et al.

, 2006) (section 7.1), which is further indication of their poor population status. Furthermore, calculation of returns relative to CSE for Atlantic salmon include salmon of fry-stocked origin; because these fish are not spawned in the wild, displaying returns as a percentage of CSE overestimates the degree to which the population is achieving self-sustainability.

Table 2—Adult Returns to the Small Coastal Rivers, the Penobscot River, the Kennebec River, and the Androscoggin River From 2001 to 2007. These Data are Summarized From Table 3.2.1.2 and Table 16 in the United States Atlantic Salmon Assessment Committee Report (USASAC, 2008)

Year

Small coastal

rivers

Penobscot River trap count

Kennebec River trap count

Androscoggin River trap count

Total known

returns

2001

103

785

893

2002

780

819

2003

1112

1191

2004

1323

1416

2005

985

1066

2006

1044

1144

2007

925

1014

Counts not conducted on the Kennebec until 2006.

Table 3—Adult Returns to Rivers Within the Freshwater Range of the GOM DPS by Origin in 2007. These Data Are Summarized From Table 1 in the United States Atlantic Salmon Assessment Committee Report (USASAC, 2008)

River

Hatchery-origin

Naturally-reared

Total

Androscoggin

Kennebec

Dennys

Narraguagus

Other GOM DPS

Penobscot

802

123

925

Total

830

184

1014

Declines in both hatchery-origin and naturally reared salmon are evident in the Penobscot River (Table 4). Declines in hatchery-origin adult returns are less sharp because of the effects of hatcheries. In short, hatchery supplementation over this time period has been relatively constant, generally fluctuating around 550,000 smolts per year (USASAC, 2008). In contrast, the number of naturally-reared smolts emigrating each year is likely to decline following poor returns of adults. Although it is impossible to distinguish truly wild salmon from those stocked as fry, it is likely that some portion of naturally reared adults are wild. Thus, wild smolt production would suffer 3 years after there were low adult returns, because the progeny of adult returns typically emigrate 3 years after their parents return. The relatively constant inputs from smolt stocking coupled with the declining trend of naturally reared adults result in the apparent stabilization of hatchery-origin salmon and the decline of naturally reared components of the GOM DPS observed over the last 2 decades.

Table 4—Adult returns, by origin (hatchery-origin and naturally reared) and age (1sw Indicates the Individual Spent One Winter at Sea; 2sw Indicates the Individual Spent Two Winters at Sea; 3sw Indicates the Individual Spent Three Winters at Sea; and Repeat Indicates the Individual was a Repeat Spawner) to the Penobscot River from 1996 to 2007

Year

Hatchery-origin

1sw

2sw

3sw

Repeat

Naturally reared

1sw

2sw

3sw

Repeat

Total

1996

484

1,218

303

2,044

1997

243

934

153

1,355

1998

238

793

133

1,210

1999

223

568

108

968

2000

167

265

534

2001

195

466

785

2002

363

344

780

2003

196

847

1,112

2004

276

952

1,323

2005

269

678

985

2006

338

653

1,044

2007

226

575

925

The influence of CBNFH and GLNFH on abundance of the GOM DPS is positive, thus reducing short-term extinction risks to the GOM DPS. Below, we briefly describe the three mechanisms by which the conservation hatchery programs positively affect the abundance of the GOM DPS:

1. Stocking of large numbers of smolts (Penobscot beginning in 1974, Dennys beginning in 2001, and Narraguagus beginning in 2008) increases adult returns, thus reducing demographic risks (

i.e.

, extinction risks) to populations that would otherwise be smaller.

2. Stocking large numbers of smolts also reduces the risks of catastrophic loss because at least one cohort is always at sea and could be collected as broodstock in case of a catastrophic event in freshwater (

e.g.

, a large contaminant spill) or in a hatchery (

e.g.

, disease outbreak).

3. Rivers without large scale fry stocking efforts have even fewer adult returns than those rivers with large scale stocking efforts. Further, rivers that lack significant hatchery contributions (fry stocking) have not experienced stable

levels of adult returns since the decline in marine survival in the early 1990s. For example, redd counts in the Ducktrap River (a river which is not stocked) have been steadily declining since the 1990s to a point where no redds were found in the Ducktrap River in 2007, a year with favorable conditions for redd counting and over 90 percent of spawning habitat surveyed (USASAC, 2008).

As illustrated by the above data, the abundance of Atlantic salmon in the GOM DPS is low and either stable or declining. The proportion of fish that are of natural origin is very small (approximately 10 percent) and is continuing to decline. The conservation hatchery has assisted in slowing the decline and helped stabilize populations at low levels, but has not contributed to an increase in the overall abundance of salmon and has not been able to halt the decline of the naturally-reared component of the GOM DPS.

Productivity

The historic productivity of the GOM DPS is unknown. Over long time frames, it is expected that productivity fluctuated widely according to a diverse range of biotic factors such as food availability and abiotic factors such as temperature regime and sea level.

Contemporary productivity rates for the GOM DPS can be inferred from replacement rates. In short, populations with a replacement rate of 1.0 or higher are stable or increasing while populations with a replacement rate less than 1.0 are declining. The USASAC has estimated the replacement rate for the GOM DPS (as listed in 2000) over the last several years. Replacement rate for the GOM DPS (as listed in 2000) had been below 1.0 for several generations until 2007, when replacement rate for the 2002 spawning cohort was 1.47. This translates to on average, every adult returning in 2002 replacing itself with 1.47 adults in 2007. While this increase is promising, it only represents 1 year; thus, it is premature to conclude that this is indicative of an increasing trend.

Replacement rate is a fairly imprecise measurement of productivity for several reasons. First, tracking adult to adult return rates of naturally reared fish necessarily includes those fish that result from stocking. Thus, it is not true replacement of fish in the wild because each river with substantial returns of adults is stocked with fry, or smolts as in the case of the Penobscot, Narraguagus, and Dennys Rivers. This situation results in an overestimation of productivity (because it does not account for the contribution that stocking makes to adult returns) and also emphasizes the importance of hatcheries to the security of the GOM DPS. Without stocking of hatchery fry and smolts, adult returns would presumably be lower and would result in even lower replacement rates.

The influence of hatcheries on productivity is not known with certainty, but overall productivity (even with hatchery supplementation) is quite low. The first goal of the captive broodstock program is to facilitate the recovery of the natural populations and minimize the risk of further decline or loss of individual populations (Bartron

et al.

, 2006). Over time, more adult returns should successfully spawn in the wild and result in replacement rates above 1.0. However, insufficient data exist to determine whether adult returns from hatchery contributions result in more spawners and ultimately more truly wild-origin adult returns. The National Research Council (NRC, 2004) and the Sustainable Ecosystems Institute (SEI, 2007) identified this as a key limitation in available data on the recovery efforts for salmon in Maine. Without this information, it is impossible to estimate, with any certainty, the effect of hatcheries on this key population attribute (productivity). Overall, however, replacement rates less than 1.0 (as has been the case most years since the early 1990s) are indicative of low productivity.

As illustrated by the above, productivity of the GOM DPS is low and has not consistently had a replacement rate above 1.0 such that population growth would be expected. There is no current evidence that hatcheries have increased or will increase productivity in the wild.

Spatial Distribution

The historic distribution of Atlantic salmon in Maine has been described extensively by Baum (1997) and Beland (1984), among others. In short, substantial populations of Atlantic salmon existed in nearly every river that was large enough to maintain a spawning population. The upstream extent of anadromy extended far into the headwaters of even the largest rivers. For example, Atlantic salmon were found throughout the West Branch of the Penobscot River as far as Penobscot Brook, a distance over 350 river km inland (Atkins, 1870). In the Kennebec River, Atlantic salmon ranged as far inland as the Kennebec River Gorge and Grand Falls on the Dead River, 235 km inland (Foster and Atkins, 1867; Atkins, 1887).

Today, the spatial structure of Atlantic salmon is limited by obstructions to passage and also by low abundance levels. Fish passage obstructions caused the decline of many salmon populations (Moring, 2005). Within the range of the GOM DPS, the Kennebec, Androscoggin, Union, and Penobscot Rivers contain dams that severely limit passage of salmon to significant amounts of spawning and rearing habitat.

In addition, the low abundance of salmon within the range of the GOM DPS serves to concurrently limit spatial distribution through two mechanisms: (1) Lack of sufficient source populations, and (2) hatchery limitations. First, in properly functioning salmon populations, some areas have relatively abundant salmon populations such that they may serve as “source” populations. Fish from source populations may seek out areas with fewer or no competitors. This is an important dispersal mechanism for all anadromous salmonids. Over evolutionary timescales, this process led to the colonization of nearly every river in Maine by Atlantic salmon. Because the abundance of salmon is so low today, this dispersal mechanism is likely not operating and will likely not operate until trends in productivity and abundance are reversed. Second, spatial distribution is limited today by hatchery capacity. The Penobscot River alone would require 12.5 million fry in order to properly seed all presently accessible rearing habitat (Trial, 2006), while GLNFH and CBNFH can only produce roughly 3.5 million fry annually (Barton

et al.

, 2006). Thus, hundreds of thousands of otherwise suitable habitat units are currently unoccupied (NMFS, 2008). The Sheepscot, Narraguagus, Dennys, Machias, East Machias, and Pleasant Rivers are usually stocked with as many fry as are needed to properly seed the habitat, although no stocking occurs within a 50-meter buffer around areas known to have spawning activity the previous year in order to reduce competition between potentially wild and hatchery fry (described in detail by Trial, 2006). Hatchery space for the Penobscot population is limited by hatchery capacity, such that only 2.5 million fry are typically allocated and stocked into the Penobscot River annually. Other rivers within the freshwater range of the GOM DPS have been stocked to a very limited degree in some years, usually with Penobscot-origin fry (see section 5 of Fay

et al.

, 2006, for a detailed review).

The influence of hatcheries on spatial structure of the GOM DPS is positive. Without hatchery contributions, fewer juveniles would inhabit the rivers of Maine. In section 7.2., Fay

et al.

(2006)

examined recent MDMR electrofishing data, which demonstrated that rivers with large scale stocking efforts have much higher juvenile densities compared to those rivers without large scale stocking efforts. The hatchery, therefore, has allowed for maintenance of the current spatial structure of the GOM DPS. Without the hatcheries, there likely would have been a greater reduction in spatial distribution. In summary, spatial distribution of the GOM DPS is positively influenced by the Atlantic salmon conservation hatchery supplementation program in the following ways:

1. The use of captive broodstock from seven separate populations reduces the risks of random environmental and demographic events;

2. Stocking maintains the spatial distribution of the GOM DPS;

3. Stocking has been used to repopulate unoccupied areas, when determined to be an appropriate management action.

As illustrated above, the spatial distribution of the GOM DPS has been significantly reduced from historic levels and is currently limited by low abundance of Atlantic salmon. However, we conclude that spatial distribution would have experienced even greater reductions without the influence of hatcheries.

Genetic Diversity

In general, large populations have higher levels of genetic diversity than small populations. As population sizes decrease, and the potential for mating related individuals increases, the threat of inbreeding in a population also increases. Inbreeding has been documented to decrease overall fitness of a population (Spielman

et al.

, 2004; Lynch and O'Hely, 2001), reducing the long-term population viability. Thus, maintaining sufficient levels of genetic variability and structure is of utmost importance to endangered and threatened species.

Historical salmon populations within the range of the GOM DPS were several orders of magnitude higher than they are today and occupied a greater diversity of habitats. As such, genetic diversity levels of the GOM DPS are likely to have been higher historically as well. Lage and Kornfield (2006) demonstrated significant reductions in diversity and effective population size in the Dennys River from 1963 to 2001. This raises concern that diversity levels today are lower than historical levels.

However, results from genetic surveys conducted by the USFWS suggest that, overall, the GOM DPS is not currently suffering significant negative effects due to inbreeding. Estimates of genetic diversity (

e.g.

, average heterozygosity, relatedness coefficients, and allelic diversity and frequency) within captive populations are evaluated within the hatchery broodstocks according to the CBNFH Broodstock Management Plan (Bartron

et al.

, 2006). Broodstock management is evaluated annually and is revised as needed to minimize the potential for inbreeding and maintain genetic diversity (Bartron

et al.

, 2006).

The effects of hatcheries on genetic diversity of the GOM DPS are both positive and negative; however, the positive effects outweigh the negative effects at this time. Below, we describe the positive and negative effects of hatcheries on diversity levels of the GOM DPS. Genetic diversity of the GOM DPS is positively influenced by the Atlantic salmon conservation hatchery supplementation program in the following ways:

1. A rigorous genetic screening program reduces the risks of outbreeding depression that may otherwise result from aquaculture escapees or their progeny being integrated into the hatchery program;

2. The effective use of spawning protocols preserves genetic variation inherent in each of the genetically unique river populations maintained at CBNFH, ensures the long-term maintenance of genetic variation, and minimizes the potential for inbreeding or domestication selection and associated reductions in fitness in the wild;

3. The use of pedigree lines for those populations most at risk reduces the chance of catastrophic loss of an entire population;

4. Stocking of juveniles into rivers significantly reduces the risks of catastrophic loss at CBNFH. That is, if a catastrophic loss of one or more captive broodstock lines occurred at CBNFH, a component of the genetic variability lost could be recovered by collecting parr for broodstock.

There are significant risks associated with the current reliance on hatcheries for the persistence of the GOM DPS. As mentioned previously, these risks include artificial selection, inbreeding depression, and outbreeding depression.

Over the long term, artificial selection for the hatchery environment is considered a threat to survival. If parr are not recovered in numbers sufficient for broodstock and spawning requirements, it becomes necessary to establish pedigree lines, which means that natural selection from fry to parr stage may no longer be incorporated into the life cycle (details of pedigree line management are in Fay

et al.

, 2006, and Bartron

et al.

, 2006). Establishment of pedigree lines is only resorted to in instances when one of the following criteria is met:

1. The number of broodstock for a particular population is low (less than collection target);

2. There is a threat of few or no hatchery or wild spawned parr being recovered; or

3. Loss of family variation through general parr collection practices is projected to cause appreciable losses in local population diversity in the near future.

In recent years, pedigree lines have been established for broodstock from the Pleasant River (due to insufficient parr collection) and the Dennys River (due to a large aquaculture escape event). Over time, this process could result in a population that is well adapted to the artificial environment and poorly adapted to the natural environment; this form of artificial selection is widely known as domestication selection (Hey

et al.

, 2005).

Both inbreeding depression and outbreeding depression are widely accepted as potential risks in artificial propagation programs. As population sizes decrease, and the potential for mating related individuals increases, the threat of inbreeding in a population also increases. Inbreeding may also decrease overall fitness of a population (Spielman

et al.

, 2004; Lynch and O'Hely, 2001), reducing the long-term population viability and, therefore, inhibiting the success of restoration and recovery efforts. Of similar concern is the threat of outbreeding depression and decreased fitness resulting from the mating of individuals from populations with significantly different genetic composition.

Over time, these risks will increase and more negative effects may appear. At this time, however, results from USFWS genetic screening programs suggest that domestication, inbreeding depression, and outbreeding depression do not appear to be negatively impacting the GOM DPS.

Summary

In summary, all available metrics of abundance, productivity, spatial distribution, and genetic diversity are cause for concern for the GOM Atlantic salmon DPS. Contemporary abundance estimates of adult spawners are several orders of magnitude lower than historical abundance. Estimates of productivity are well below those required to sustain a viable population over the long term. The spatial distribution of the GOM DPS has been severely reduced relative to historical

distribution patterns. Genetic diversity levels, though apparently stable, are likely much lower than they were historically (Lage and Kornfield, 2006) and lower than more abundant populations in Canada (Spidle

et al.

, 2003). Finally, while conservation hatcheries positively influence several of these metrics, they have not yet been able to reverse the observed declines in wild adult spawners. In the following sections of this final rule, we use this information combined with recent population viability analyses to analyze the current conservation status of the GOM DPS.

Population Viability Analyses

Statistical methods can be used to quantitatively estimate population growth, and more importantly, extinction probabilities for a species. The simplest type of model to perform this can be referred to as a simple Population Viability Analysis (PVA). A simple PVA quantitatively estimates population growth and extinction probabilities for a single population (Dennis

et al.,

1991). A simple PVA is a stochastic exponential growth model of population size. These types of models are best used with census data where the sampling variability is small compared to the population or environmental variability (Dennis

et al.,

1991).

More complex versions of PVAs have been developed where life history characteristics, such as the age distribution within abundance measures, are accounted for within the model. In addition, a modified approach has been developed where different life history processes are compartmentalized within the model allowing for the incorporation of such things as juvenile survival rates, adult survival rates, habitat limitations/degradation, age-specific fecundity, or migration rates (Brook

et al.,

1999; Marmontel, 1997; Ratner

et al.,

1997; Zhang and Wang, 1999). Other complex PVAs have been developed to help managers decide between competing management regimes, whereby population growth (or conversely extinction probability) can be predicted based on changes to survival at one or more life stages. Thus, PVA models can vary widely in complexity.

Some general caveats are associated with the use and interpretation of PVAs. It is particularly important to recognize that PVAs are merely projections about what might happen in the future based on the data used to compile the model and assumptions made to address uncertainties (Ralls

et al.,

2002; Legault, 2005). Because PVAs do not account for all potential sources of future environmental variation and because of the uncertainty inherent in predicting future conditions, especially over longer timeframes, we use PVA results cautiously and consider them as just one of the pieces of information we evaluate in determining a species' conservation status.

For the purpose of considering the risks of extinction for Atlantic salmon, we have two PVAs to consider: the simple PVA conducted by Fay

et al.

(2006), and the SalmonPVA (Legault, 2004; Legault, 2005). Both are instructive in considering the relative extinction risks to the GOM DPS. They also help clarify the importance of marine survival and hatchery supplementation in considering extinction risks. It is important to note that the Services look at estimates of how extinction probability changes over multiple timeframes and not at only a single estimate of the extinction probability for a single time period. This is consistent with the cautions noted by Fay

et al.

(2006) and Legault (2005).

Fay

et al.

(2006) used a simple PVA to assess the extinction risk to the GOM DPS as defined in this final rule. This PVA examined a number of different scenarios and provided a wide range of alternative outputs. In particular, it included three different endpoints: 1 individual, 50 individuals, and 100 individuals. An endpoint greater than zero, referred to as a quasi-extinction threshold or QET, reflects the point at which the population is considered to be functionally extinct, that is, non-recoverable due to loss of fitness of individuals, inability of individuals to carry out essential population functions, or other problems. Compared with use of an extinction threshold of zero, use of a QET would produce a higher probability of extinction over the same time period or the same probability of extinction over a shorter time period. An extinction threshold of one individual, which recognizes that there is no longer a population to model, is not typically referred to as a QET; compared to a threshold of zero individuals, it will not materially affect a model's results. Although a model's results using different extinction thresholds are not directly comparable, they do provide useful information about the condition of the population over time.

Fay

et al.

(2006) presented a range of estimated extinction risks for a variety of time horizons (0 to 100 years, with 20-year intervals). This analysis used adult return data from two time series (1980-2004 and 1991-2004) to estimate population growth and extinction probabilities for the GOM DPS. The two time series were separated because of the regime shift in marine survival observed for Atlantic salmon throughout the North Atlantic that began in 1991 (ICES, 2005). This regime shift represents a change in productivity and marine survival of Atlantic salmon in the Northwest Atlantic that has persisted to date. In short, projections for the time period 1980 to 2004 are more “optimistic” because those data include roughly 10 years of higher marine survival; projections for the time period 1991 to 2004 are more “pessimistic” because they only include observations during the recent period of lower marine survival. Using this method, Fay

et al.

(2006) provided a wide range of extinction risks, but all scenarios considered clearly trended toward extinction. Comparing the two time series clearly shows the importance of marine survival; extinction risks are more severe for the 1991 to 2004 time series (Figure 3) compared to the 1980 to 2004 time series (Figure 2).

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The results of the Fay

et al.

(2006) PVA are based solely on the dynamics of the population during the timeframes examined (1980 to 2004) and are dependent on the following assumptions: (1) Hatchery supplementation continues into the future for up to 100 years at current levels with similar survival rates, and (2) similar threats to the species remain operative into the future (

i.e.

, environmental conditions remain unchanged). The Fay

et al.

(2006) PVA does not include the risk of disruptions to hatchery operations (

e.g.

, due to disease outbreak) or the risk of genetic effects (such as inbreeding and domestication selection described above) of hatchery supplementation.

The SalmonPVA (Legault, 2004) was developed for the GOM DPS of Atlantic salmon as listed in 2000 and does not include the Penobscot population. Given that smaller initial population sizes exacerbate the extinction process (Holmes, 2001), the probability of extinction for any given time period for the GOM DPS as defined in this final rule, which includes the Penobscot population, might be lower than the estimates produced by the model for the GOM DPS as listed in 2000. However, the Penobscot population is also in decline and subject to many of the same, as well as additional, environmental stressors. Thus, the model results are still generally instructive for this analysis. The SalmonPVA model was developed to aid in the formation of delisting criteria for the GOM DPS as listed in 2000 and to assess the efficacy of different management strategies towards this delisting goal.

The SalmonPVA (Legault, 2004, 2005) incorporates all salmon life stages, different survival rates for each stage, four different marine survival scenarios, freshwater habitat capacity, harvest, straying rates, and hatchery stocking as inputs into the model. Extinction in the SalmonPVA was defined as no fish alive at any life stage; this model, unlike the Fay

et al.

(2006) PVA, does not use QETs (

i.e.

, it does not identify an earlier point in decline at which the population would become functionally extinct).

The SalmonPVA (Legault, 2004, 2005) demonstrates that current levels of hatchery supplementation may reduce extinction risk to the GOM DPS as listed in 2000 depending on the rate of marine survival. In simulations where current low marine survival estimates increased to the mean of the last 30 years, the SalmonPVA estimated that the extinction risk in the next 100 years (for the GOM DPS as listed in 2000) was approximately 1 percent in simulations where hatchery supplementation continued for 50 years, 72 percent if continued hatchery supplementation was reduced from 50 years to 30 years, and near 100 percent if hatchery supplementation ceased in 10 years. Furthermore, in simulations using a constant low marine survival scenario representing the current environment, there was a 100 percent chance of extinction within 100 years regardless of the number of years of stocking, and extinction occurred within 20 years of the last stocking event.

Like the results of the Fay

et al.

(2006) PVA, the results of the SalmonPVA (Legault 2004, 2005) are dependent on assumptions about future conditions remaining the same. These assumptions include the level of hatchery supplementation (

i.e.

, number of fish stocked), freshwater survival, freshwater carrying capacity, and straying rates of adult fish among rivers. Also like the Fay

et al.

(2006) PVA, the SalmonPVA (Legault 2004, 2005) does not include the risk of disruptions to hatchery operations (

e.g.

, due to disease outbreak) or the genetic risks (such as inbreeding and domestication selection described above) of hatchery supplementation. It is expected that extinction would proceed much faster than indicated by the model's simulation results if and when these effects become operative in the GOM DPS. The SalmonPVA does include scenarios where hatchery operations cease (without attributing that to a cause which could be lack of funding, disease outbreak or evidence of significant genetic risks), and those scenarios illustrate that declines rapidly follow the elimination of the hatchery.

Both the Fay

et al.

(2006) and Legault (2004, 2005) PVAs assumed that hatchery supplementation would continue at its present level even when there were 100 or fewer returning adults in the Penobscot. However, hatchery supplementation (in particular, smolt stocking) could not continue at the same level in the future if returning adults fell below 150 because that is the number of adults necessary to make full use of the current conservation hatchery capacity for the smolt stocking program that currently sustains the Penobscot population (section 5.2.1 of Fay

et al.

, 2006). Smolt stocking increases the number of returning adults, so if the full number of smolts could not be produced and stocked, there would be fewer adults returning which would result in an even smaller population. Adult returns to the Penobscot constitute a substantial proportion of the total returns to the GOM DPS (Table 2).

Additional problems would arise if there were 150 or fewer adult returns to the Penobscot. If there were only 150 adult returns, it is likely all of their production would be used for smolt production (M. Bartron, USFWS, pers. comm., 2009). Fry production for the Penobscot would have to come from domestic broodstocks. If the domestic broodstocks (at GLNFH and other sources) were not able to be sustained because all the adult production was being used for smolt production, then there would be no fry production for the Penobscot. If the total production from 150 fish were used to produce smolts, and not to replenish domestic broodstocks, then those backup broodstocks for the Penobscot would no longer exist (M. Bartron, USFWS, pers. comm., 2009). Fry production in the other rivers (those maintained at CBNFH) would continue.

If there were 150 or fewer adults in the Penobscot, or if smolt stocking and fry stocking was curtailed, there would be an increased risk of genetic problems because the rate of loss of genetic diversity (and the potential for inbreeding) is inversely proportional to the effective population size (number of individuals reproducing). As the number of individuals reproducing decreases, the rate of loss of genetic diversity increases, as does the potential for inbreeding. The potential for loss of genetic diversity further increases when populations remain low for extended periods of time. A faster population decline and genetic impacts would increase the probability of extinction beyond the predictions of the two PVAs.

In addition to providing estimates of extinction probability, the Fay

et al.

(2006) and Legault (2004, 2005) PVAs also provide useful projections regarding the condition of the population over time. For example, the results of the Legault (2004, 2005) PVA demonstrate that, while the estimated extinction probability may be low under certain scenarios of long-term hatchery supplementation and improved marine survival, the population can continue to decline to extinction. For the model scenario producing an extinction probability estimate of 1 percent in 100 years if marine survival increased to the 30-year average and hatchery supplementation continued for 50 years, the replacement rate was still less than 1, indicating the simulated GOM DPS was still in decline. Also under this scenario, the model predicted that three of the eight river populations would be extirpated.

In summary, PVA results must be interpreted carefully. The two PVAs considered here do not include risks associated with other sources of environmental variation (

e.g.

, aquaculture escapement and disease

outbreak in the wild) identified in the Summary of Factors Affecting the Species section. Because these PVAs do not account for all potential sources of future environmental variation, and because of the uncertainty inherent in predicting future conditions, especially over longer timeframes, we do not consider the numerical estimates of extinction probabilities in the PVA of Fay

et al.

(2006) and the SalmonPVA (Legault 2004, 2005) to be the actual extinction probabilities of the newly defined GOM DPS.

We have no information to indicate that marine survival will significantly improve. We find that, based on the available trend information, it is most reasonable to assume that marine survival will continue at approximately its current low level. Therefore, we conclude that the results of the Fay

et al.

(2006) PVA and the Legault (2004, 2005) PVA that are based on marine survival values above the current low level are unrealistic.

Also, based on information on diseases (see Factor C in the Factors Affecting the Species section of this final rule), or concerns such as catastrophic loss to water supply or feed contamination (P. Santavy, USFWS, pers. comm., January 23, 2009), there is a risk of disruptions to hatchery operations. Based on the information on long-term hatchery operations (NRC, 2004; Fay

et al.

, 2006, at section 8.5.1; SEI, 2007), there is a risk of genetic problems from hatchery supplementation. At present, these risks are not quantifiable, and are therefore not accounted for in either PVA. However, we find that these risks are substantial in the long term because of the dependence on the conservation hatchery program.

Because the models do not include the risk of disruptions to hatchery operations, the risk of genetic effects of hatchery supplementation, and risks associated with other sources of environmental variation, we conclude that all of the results of the Fay

et al.

(2006) PVA and the Legault (2004, 2005) PVA may considerably underestimate the probability of extinction. Nevertheless, the Fay

et al.

(2006) PVA and the Legault (2004, 2005) SalmonPVA do tell us much about certain factors affecting the status of the GOM DPS as defined in this rule, especially the significance of hatchery supplementation and marine survival, and we use this information to provide important context for evaluating threats in the following sections of this rule.

Previous Federal Actions

In 1991, the FWS designated Atlantic salmon in five rivers in Downeast Maine (the Narraguagus, Pleasant, Machias, East Machias, and Dennys Rivers) as Category 2 candidate species under the ESA (56 FR 58804; November 21, 1991). Both Services received identical petitions in October and November of 1993 to list the Atlantic salmon (

Salmo salar

) throughout its historic range in the contiguous United States under the ESA. On January 20, 1994, the Services found that the petition presented substantial scientific information indicating that the petitioned action may be warranted (59 FR 3067).

The Services conducted a joint review of the species in January 1995, and found that the available biological information indicated that the species described in the petition, Atlantic salmon throughout its range in the United States, did not meet the definition of “species” under the ESA. Therefore, the Services concluded that the petitioned action to list Atlantic salmon throughout its historical United States range was not warranted (60 FR 14410; March 17, 1995). In the same notice, the Services determined that a DPS consisting of populations in seven rivers (the Dennys, East Machias, Machias, Pleasant, Narraguagus, Ducktrap, and Sheepscot Rivers) did warrant listing under the ESA. On September 29, 1995, after reviewing the information in the status review, as well as state and foreign efforts to protect the species, the Services proposed to list the seven rivers DPS as a threatened species under the ESA (60 FR 50530; September 29, 1995). The proposed rule contained a special rule under section 4(d) of the ESA which would have allowed for a State plan, approved by the Services, to define the manner in which certain activities could be conducted without violating the ESA. In response to that special provision in the proposed rule, the Governor of Maine convened a task force that developed a Conservation Plan for Atlantic Salmon in the seven rivers. That Conservation Plan was submitted to the Services in March 1997.

The Services reviewed information submitted from the public, current information on population levels, and assessed the adequacy of the Maine Atlantic Salmon Conservation Plan, and, on December 18, 1997, withdrew the proposed rule to list the seven rivers DPS of Atlantic salmon as threatened under the ESA (62 FR 66325). In that withdrawal notice, the Services redefined the species under analysis as the GOM DPS to acknowledge the possibility that other populations of Atlantic salmon could be added to the DPS if they were found to be naturally reproducing and to have wild stock characteristics. NMFS maintained the GOM DPS as a candidate species to acknowledge ongoing concern over the species' status. In the 1997 withdrawal notice, the Services outlined three circumstances under which the process for listing the GOM DPS of Atlantic salmon under the ESA would be reinitiated: (1) An emergency which poses a significant risk to the well-being of the GOM DPS is identified and not immediately and adequately addressed; (2) the biological status of the GOM DPS is such that the DPS is in danger of extinction throughout all or a significant portion of its range; or (3) the biological status of the GOM DPS is such that the DPS is likely to become endangered in the foreseeable future throughout all or a significant portion of its range.

The Services received the State of Maine 1998 Annual Progress Report on implementation of the Conservation Plan in January 1999. On January 20, 1999, the Services invited comment from the public on the first annual report and other information on protective measures and the status of the species. The comment period remained open until March 8, 1999 (64 FR 3067). The Services reviewed all comments submitted by the public and provided a summary of those, along with their own comments, to the State of Maine in March 1999. The State of Maine responded to the Services' comments on April 13, 1999.

In order to conduct a comprehensive review of the protective measures in place and the status of the species, as was committed to in the 1997 withdrawal notice, the BRT was reconvened to update the January 1995 Status Review for Atlantic salmon. The 1999 Status Review was made available on October 19, 1999 (64 FR 56297). On November 17, 1999, the Services published a proposed rule to list as endangered the GOM Atlantic salmon DPS, which was defined to include all naturally reproducing remnant populations of Atlantic salmon from the Kennebec River downstream of the former Edwards Dam site northward to the mouth of the St. Croix River at the United States-Canada border. At that time, the Services stated that, to date, they had determined that these populations were found in the Dennys, East Machias, Machias, Pleasant, Narraguagus, Sheepscot, and Ducktrap Rivers and in Cove Brook, all in eastern Maine. On November 17, 2000 (65 FR 69459), the Services published a final rule listing the GOM Atlantic salmon

DPS as endangered. In that final rule, we noted that a determination as to the appropriateness of adding the mainstem and upper tributaries of the Penobscot River to the DPS would be made upon completion of genetic analyses.

The 2006 Status Review for Anadromous Atlantic Salmon (

Salmo salar

) in the United States (Fay

et al.

, 2006) assessed genetic and life history information and concluded that the GOM DPS as defined in 2000 should be redefined to encompass the Penobscot, Kennebec, and Androscoggin Rivers.

We received a petition to list the “Kennebec River population of anadromous Atlantic salmon” as an endangered species under the ESA on May 11, 2005. NMFS published a notice in the

Federal Register

on November 14, 2006 (71 FR 66298), concluding that the petitioners (Timothy Watts, Douglas Watts, the Friends of Merrymeeting Bay, and the Maine Toxics Action Coalition) presented substantial scientific information indicating that the petitioned action may be warranted.

On September 3, 2008 (73 FR 51415), we proposed to revise the extent of the GOM DPS and list the DPS as endangered; we also announced our 12-month finding that listing was warranted for the petition to list Atlantic salmon in the Kennebec River as endangered. On September 5, 2008 (73 FR 51747), NMFS proposed to designate critical habitat for the revised GOM DPS of Atlantic salmon.

The Services jointly administer the ESA as it applies to anadromous Atlantic salmon. In 2006, the USFWS Region 5 and NMFS Northeast Region entered into a Statement of Cooperation to divide responsibility for ESA implementation with respect to Atlantic salmon in order to enhance efficiency and effectiveness. Experience implementing this agreement, changes in structure of the recovery program, and anticipated increases in workload associated with this listing action caused the Services to revisit the 2006 agreement. A new Statement of Cooperation has been signed which clarifies roles and responsibilities between the Services. The Statement of Cooperation assigns the following responsibilities to NMFS: critical habitat designation; section 7 consultations (for both the species and critical habitat) on activities within estuaries and marine waters; ESA activities and actions to address dams; assessment activities in the estuary and marine environment; and international science and management. The Statement of Cooperation assigns the following responsibilities to USFWS: Administrative lead for development of a new recovery plan; section 10 recovery permits; section 10 habitat conservation plans (for all activities except dams); section 7 consultations (for both the species and critical habitat) on activities in freshwater (except dams); and the conservation hatchery program.

Summary of Comments

With the publication of the proposed listing determination for the GOM DPS on September 3, 2008, we announced a 90-day public comment period extending through December 2, 2008. We held two public hearings at two different locations to provide additional opportunities and formats to receive public input as announced on October 21, 2008 (73 FR 62459). A joint NMFS/FWS policy requires us to solicit independent expert review from at least three qualified specialists, concurrent with the public comment period (59 FR 34270; July 1, 1994). In December 2004, the Office of Management and Budget (OMB) issued a Final Information Quality Bulletin for Peer Review establishing minimum peer review standards, a transparent process for public disclosure, and opportunities for public input. The OMB Peer Review Bulletin, implemented under the Information Quality Act (Pub. L. 106-554), is intended to provide public oversight on the quality of agency information, analyses, and regulatory activities, and applies to information disseminated on or after June 16, 2005. We solicited technical review of the proposed listing determination from four independent experts, and received reviews from two of these experts. The independent expert review under the joint NMFS/FWS peer review policy collectively satisfies the requirements of the OMB Peer Review Bulletin and the joint NMFS/FWS peer review policy.

Comments were submitted from interested individuals; state, Federal and tribal agencies; fishing groups; environmental organizations; industry groups; and peer reviewers with scientific expertise. The summary of comments and our responses below are organized into seven general categories: (1) Tribal comments (2) peer review comments; (3) comments on the delineation of the GOM DPS; (4) comments on the conservation status of the GOM DPS; (5) comments on the Services' identification and consideration of specific threats; (6) comments on the consideration of conservation efforts in general as well as in relation to the conservation status of the GOM DPS; and (7) comments on the Federal management of the GOM DPS.

During the public comment period, the Services met with a number of groups to address specific concerns and questions on the proposed listing decision. The hydropower industry, agriculture industry, and various state agencies were among the groups with which the Services met. These discussions focused on clarification of information in the proposed rule and the potential implications of the listing decision on Atlantic salmon management and the ongoing operations of industry. These meetings were not held to solicit or receive comments on the proposed rule, but rather to provide clarification. Meeting participants were instructed to submit comments on the proposed rule through the regular means, and those are identified and addressed in the comments section of this rule. The Services also met with representatives from some of the Maine Tribes, including the Penobscot Indian Nation, The Houlton Band of Maliseets, the Aroostook Band of Micmacs, and the Passamaquoddy Tribe. The Services appreciate the importance of our Federal trust responsibilities and the spirit of government-to-government consultation embodied in Secretarial Order 3206 (American Indian Tribal Rights, Federal-Tribal Trust Responsibilities, and the Endangered Species Act) and Executive Order 13175 (Consultation and Coordination with Indian Tribal Governments). The focus of the government-to-government consultation was on the implications of the listing decision on Atlantic salmon management and exploring options to further enhance our cooperation on Atlantic salmon recovery.

Tribal Comments

Comment 1:

The Penobscot Indian Nation commented that it maintains its right to directly take Atlantic salmon for sustenance purposes. Penobscot Indian Nation members have not lethally taken an Atlantic salmon since 1988 at which time two Atlantic salmon were harvested for ceremonial purposes. The Penobscot Indian Nation has not exercised its right to take any Atlantic salmon for traditional purposes since that time based upon concerns about the health of the Penobscot Atlantic salmon population. The Penobscot Indian Nation stated that it will continue to abstain from taking any Atlantic salmon until the status of the Penobscot population is healthy enough to be able to sustain some level of harvest.

Response:

The Services appreciate the importance of Atlantic salmon to the Penobscot Indian Nation in particular as well as other Maine Tribes. The Services recognize both the Penobscot Indian

Nation's tribal rights and the Services' responsibility to implement the ESA. Given that Penobscot Indian Nation has not exercised its right to take Atlantic salmon since 1988 on a voluntary basis, the Services believe that there is no conflict provided the Penobscot Indian Nation continues to voluntarily abstain from taking based upon continued concerns about the conservation status of the Penobscot population.

Comment 2:

The Penobscot Indian Nation commented that it would not take any position on whether the species should be listed as threatened or endangered. The Penobscot Indian Nation defers to the Services' expertise to make that determination.

Response:

The Services have provided justification for the listing decision in this final rule.

Peer Review Comments

Comment 3:

Both reviewers agreed with the delineation of the GOM DPS of Atlantic salmon. However, both reviewers felt there were parts of the text that could be further clarified, specifically consideration of available genetic data for the northern and southern boundaries in relation to the zoogeographic information used.

Response:

The Services received comments from both peer reviewers and the general public regarding necessary clarification of the data used to support the southern boundary delineation in particular. The Services have clarified the text in the DPS delineation section of this final rule.

Comment 4:

One of the peer reviewers stated that the discussion of the population PVA was perhaps overemphasized and could be simplified while still communicating extinction risk. The reviewer notes that there are simpler deterministic equilibrium models that could have been used to more simply state extinction risk.

Response:

The Services have clarified the text of the rule addressing PVAs and the projections. The Services acknowledge that there are a number of different types of models that could have been used to project extinction risk or demonstrate the conservation status of the species. The Services chose the PVA models because they are useful in assessing extinction risks. Further, the Atlantic salmon conservation and management community in Maine are more familiar with them than with other models, given the public's previous exposure to them during the recovery planning process and the development of the 2006 Status Review. We agree with the peer reviewer that the PVA is just one piece of information considered in the listing determination; in the text of this final rule, we have clarified our findings with respect to the PVAs and how they factor into the biological status of the species.

Comment 5:

Both reviewers noted that the proposed rule lacked necessary description for how threats were categorized as either primary or secondary threats. Neither felt that this was an incorrect way to communicate the magnitude of the threat; rather, the basis for this determination should be better explained and supported in the text.

Response:

The Services agree that the description of threats as primary or secondary could have been better explained in the proposed rule. Upon review, the Services decided to take a different approach to describing the magnitude of the threat and its influence on the conservation status of the GOM DPS under the ESA. Rather than comparing the magnitude of the threats to each other, we have identified the relative impact of each of the threats on the species and its habitat. The text has been modified accordingly.

Comment 6:

One of the reviewers had concerns about the discussion of artificial propagation under Factor E (Other Natural or Manmade Factors Affecting its Continued Existence). While the reviewer agrees with the Services' conclusion that the conservation hatchery program is reducing the risk of extinction of the GOM DPS, he highlighted areas where the text should be clarified. Specifically, the short- and long-term goals of the conservation hatchery program should be better described in relation to how the program is currently being conducted.

Response:

Upon closer review and in response to the peer review, the Services have changed the way in which artificial propagation and specifically the conservation hatchery program are described and considered. While there are both positive and negative effects resulting from any artificial propagation program, the Services have determined that it would be more appropriate to move the discussion of the role of the conservation hatchery program and its influence on the current status of the species and recovery to the section of the rule describing the status of the species rather than describing it in the section pertaining to the threats. The Services have also revised the description of the program and its role in recovery of the GOM DPS in response to comments received from both peer reviewers and the general public.

Comment 7:

One reviewer recommended minor clarifications to the text in Factor E addressing diadromous fish communities, marine survival, and competition.

Response:

The Services have clarified the text in these sections to be responsive to comments from both peer reviewers and the general public.

Comment 8:

Both reviewers commented that the section applying the

Policy for Evaluation of Conservation Efforts when making Listing Decisions (PECE)

to conservation actions was unclear and seemed incomplete. They questioned the analysis of only one conservation initiative, the Penobscot River Restoration Project (PRRP).

Response:

The Services agree that analysis of conservation efforts under PECE is more transparent if a complete analysis of a variety of efforts is included in the rule. We have revised the section addressing analysis of conservation actions.

Comment 9:

Both reviewers commented that the determination to list the GOM DPS of Atlantic salmon as endangered was sound and only suggested minor clarifications to the text.

Response:

The Services have made minor changes and clarified the text in this section.

Public Comments

Comment 10:

Many commenters believe that certain river systems, particularly the Androscoggin and the Union, should not be included within the GOM DPS boundaries. They argue that we erred in using different criteria (zoogeographic and genetic) to delineate the southern and northern boundaries of the DPS and that we should delay the decision to include the Androscoggin in the DPS until the naturally reared population in Androscoggin can be genetically characterized. Commenters also suggest that river systems where the species has been extirpated, such as the Union, should not be included within the DPS range.

Response:

The 1996 Interagency Policy Regarding the Recognition of Distinct Vertebrate Populations Under the Endangered Species Act (61 FR 4722) (DPS Policy) states that a population segment may be considered discrete in relation to the remainder of the species to which it belongs if “it is markedly separated from other populations of the same taxon as a consequence of physical, physiological, ecological or behavioral factors. Quantitative measures of genetic or morphological discontinuity may provide evidence of this separation.” The DPS Policy does not restrict the Services to using only one measure to

define discreteness of a population segment. In fact, the introduction to the second element (significance) that must be met in evaluating whether a population qualifies as a DPS says that a population segment may be considered discrete based on “one or more” of the discreteness conditions.

As more thoroughly described in the “Review of Species Delineation” section of this final rule, genetic data were available for us to delineate the northern boundary of the GOM DPS. These data show clear genetic differentiation between populations inhabiting rivers in Maine and rivers in New Brunswick, with the Dennys River population clustering more closely with the Maine population and the St. Croix River population clustering more closely with populations in New Brunswick. Therefore, we used the Dennys watershed as the northern boundary of the DPS. However, because of the combination of low numbers of Atlantic salmon in some rivers (

e.g.

, only three naturally reared adult returns to the Androscoggin River (Table 3)) and the complete extirpation of the native stock in other rivers (

e.g.

, Merrimack River), complete genetic data are not, and may never be, available for us to genetically characterize these populations.

In the absence of clear genetic information to define the southern boundary of the GOM DPS, we used ecological factors in addition to the genetic factors described above. In particular, we used the zoogeographic boundary (the Penobscot-Kennebec-Androscoggin EDU and the Laurentian Mixed Forest Province) that ecologically separates the Androscoggin watershed from watersheds to the south (

e.g.

, Saco, Merrimack, and Connecticut watersheds). EDUs, defined by Olivero (2003), are aggregations of watersheds with similar zoogeographic history, physiographic conditions, climatic characteristics, and basin geography. EDUs generally have similar physiographic and climatic conditions (Higgins

et al.

, 2005). These differences would influence the structure and function of aquatic ecosystems (Vannote

et al.

,1980; Cushing

et al.

, 1983; Minshall

et al.

, 1983; Cummins

et al.

, 1984; Minshall

et al.

, 1985; Waters, 1995) and create a different environment for the development of local adaptations than rivers to the south. Therefore, we believe this zoogeographic boundary sufficiently satisfies the criteria to define discreteness for the southern edge of the GOM DPS.

In listing the GOM DPS, our goal is ultimately to recover the species so it no longer requires the protection of the ESA. Therefore, we have delineated boundaries for the GOM DPS that include all the areas of current and historical occupation of Atlantic salmon where those salmon would be identified as belonging to the GOM DPS. During recovery planning, we will further evaluate the recovery needs of the GOM DPS. It is likely that different levels of attention will be paid to the recovery of the DPS in different watersheds, based in part on the threats within a particular watershed and the habitat potential within a watershed. Delineating the entire GOM DPS conserves this ecosystem for Atlantic salmon survival and recovery, in addition to supporting straying, providing refugia, and buffering against catastrophic events.

Comment 11:

Some commenters suggest that the boundaries of the DPS delineation should not extend into watersheds that were historically unoccupied by Atlantic salmon because they are upstream of historical, natural barriers (

e.g.

, waterfalls).

Response:

Based on the comments received, analyses by NMFS (2008), and information contained in the 2006 Status Review, we delimited the freshwater range of the GOM DPS to include only those areas downstream of substantial barrier falls. For this final rule, we have modified the geographic boundaries of the freshwater range of the GOM DPS in the Androscoggin, Kennebec, and Penobscot Basins in the following ways: All freshwater bodies in the Androscoggin Basin are included up to Rumford Falls on the Androscoggin River and up to Snow Falls on the Little Androscoggin River; all freshwater bodies in the Kennebec Basin are included up to Grand Falls on the Dead River and the un-named falls (currently impounded by Indian Pond Dam) immediately above the Kennebec River Gorge; and all freshwater bodies in the Penobscot Basin are included up to Big Niagara Falls on Nesowadnehunk Stream, Grand Pitch on Webster Brook, and Grand Falls on the Passadumkeag River. See the “Delineating Geographic Boundaries” section of this final rule.

Comment 12:

Many commenters stated that the Services did not accurately determine the conservation status of the GOM DPS. These commenters disagreed with the Services' proposal that the GOM DPS should be listed as endangered under the ESA. Instead, they argued that a threatened listing determination was more appropriate. The definition of endangered is “in danger of extinction throughout all or a significant portion of its range.” Several commenters argued the results of the PVA conducted by Legault (2004, 2005) demonstrated that the GOM DPS had a less than one percent chance of extinction provided that hatchery supplementation continued into the future. Thus, some commenters felt that the definition of threatened, “likely to become endangered * * *” was more appropriate given the role of hatcheries in preventing extinction. Commenters also cited the success of the conservation hatchery program as evidenced by the status of rivers within the 2000 GOM DPS that were supported by hatchery supplementation versus those that were not. The replacement rate reported by the USASAC was also cited as evidence of the positive contribution of the hatchery program to returns within the GOM DPS.

Response:

We agree that the conservation hatcheries (CBNFH and GLNFH) provide a buffer against short-term extinction risks. Without these facilities in place, the status of the GOM DPS would be even more dire. However, as described in the “Population Status of the GOM DPS” section of this final rule, only three of the four population attributes of interest (abundance, spatial structure, and genetic diversity) are enhanced by the conservation hatcheries. In particular, the lack of any evidence that hatchery fish have the potential to result in wild returns over successive generations remains a significant concern. While the increase in replacement rate reported in 2007 by the USASAC is a positive sign, the overall trend remains negative when taken together. Further, 1 year of positive population growth is insufficient to justify threatened status.

The extended timeframes for extinction (provided that hatchery supplementation continues) projected by Legault (2005) are further evidence of the buffering effect of hatcheries. However, these projections do not include any consideration of the negative effects of reliance on hatcheries over successive generations. Recent evidence suggests that the negative effects of domestication, inbreeding depression, and outbreeding depression can accrue over just a few generations (Araki

et al.

, 2007). While we do not believe these negative effects are substantially reducing the long-term viability of the GOM DPS at this time, each successive generation will likely have higher risks of reduced fitness because of these effects. These additive risks over time are not modeled or otherwise accounted for in the extinction risks scenarios described by Legault (2005). The PVA results of Legault demonstrate that extinction occurs quickly when the conservation hatchery is eliminated. This provides

further evidence that the wild population is currently in danger of extinction.

Finally, the SalmonPVA (Legault 2005) showed that at the constant low marine survival scenario representing the current environment, there was a 100 percent chance of extinction within 100 years regardless of the number of years of stocking, and extinction occurred within 20 years of the last stocking event. Legault (2005) demonstrated that an increase in marine survival substantially decreased the extinction probabilities. The scenario in which Legault found there to be a 1 percent chance of extinction assumed an increase in marine survival to the high of the previous 30 years. Unfortunately, we have no information to indicate that marine survival will significantly improve; therefore, there is no scientifically sound basis for assuming there is only a one percent chance of the GOM DPS going extinct.

Comment 13:

One commenter felt that both hatchery-origin and naturally reared Atlantic salmon should be equally weighted in terms of their population contribution to the GOM DPS. This commenter felt that the inclusion of both hatchery-origin and naturally reared Atlantic salmon in the GOM DPS was inconsistent with the way in which the Services weighted the relative contribution of each group to recovery. The Services' determination of the conservation status of the GOM DPS placed a higher weight on naturally reared fish in terms of their contribution to recovery versus hatchery origin fish (fish stocked as parr, smolts, or adults).

Response:

The stated purpose of the ESA is “to provide a means whereby the ecosystems upon which endangered species and threatened species depend may be conserved” (16 U.S.C. § 1531(b)). Using captive propagation as a recovery tool is clearly warranted when necessary, as in the case of the GOM DPS. However, the intent of the ESA is quite clear: the ultimate goal of species recovery efforts should be recovery in the wild, free from human intervention. While CBNFH and GLNFH clearly reduce the immediate risk of extinction of the GOM DPS, they have not been shown to substantially contribute to recovery in the wild. The influence of hatcheries on productivity is not known with certainty, but overall productivity (even with hatchery supplementation) is quite low. Hatchery fish are included in the GOM DPS because they are essential to recovery, and the sole purpose of the conservation hatchery is recovery. But, recovery means recovery in the wild, so the goal of the hatchery is to, over time, increase the percentage of returns that are of wild origin to the point that the GOM DPS becomes self-sustaining and is no longer dependent on the hatchery. Over time, more adult returns should successfully spawn in the wild, resulting in replacement rates above 1.0. However, the idea that adult returns from hatchery contributions result in more spawners and, ultimately, more truly wild-origin adult returns, remains an untested hypothesis. The National Research Council (NRC, 2004) and the Sustainable Ecosystems Institute (SEI, 2007) identified this as a key limitation in available data on the recovery efforts of salmon in Maine. Without this information, it is impossible to estimate, with any certainty, the effect of hatcheries on this key population attribute (productivity). The conservation hatchery has assisted in slowing the decline and helped stabilize populations at low levels, but has not contributed to an increase in the overall abundance of wild salmon.

Comment 14:

Several commenters felt that the Services' listing determination placed too much emphasis on the potential for a catastrophic failure at the conservation hatchery facilities. Commenters acknowledged that this may have been an issue when the Services initially listed the GOM DPS in 2000, given that all broodstock were held at CBNFH. However, the expansion of the GOM DPS to include the Penobscot and other rivers means that there are now several facilities that house broodstock (

e.g.

, GLNFH, the USDA facility, and the Cooke Facility on the Kennebec). Thus, loss of all broodstock due to a catastrophic failure is highly unlikely.

Response:

The Services agree that the loss of all potential broodstock would be extremely unlikely. However, it would not take the loss of all broodstock to significantly jeopardize the long-term viability of the GOM DPS. Catastrophic broodstock loss or a catastrophic loss of fry, parr, or smolt cohorts would result in a decrease in effective population size, loss of genetic diversity, and a multi-year lag while life stages rebuild, during which time there would be limited or no hatchery production or stocking.

Domestic broodstock for the Penobscot is currently maintained at facilities in addition to GLNFH. These domestic broodstocks should be viewed as backups. These sources are meant to be replenished annually (

i.e.,

new domestic broodstock lines are created each year) for GLNFH to reduce long-term selection to the hatchery environment. If there was a situation where the numbers of adult returns were reduced to 150 or less, then all production would go toward smolt production and not to fry stocking or to replenish domestic broodstocks. These backup broodstocks would no longer exist (M. Bartron, USFWS, pers. comm., 2009). If these domestic broodstocks were used to propagate future domestic broodstocks, there would be greater concerns about the decreased fitness of their offspring in the wild from successive generations of selection to captivity.

The Services have concluded that the conservation hatcheries significantly contribute to the maintenance of the genetic diversity of the GOM DPS. However, there are both long-term and short-term risks of reliance on hatcheries that have been considered above in the “Population Status of the GOM DPS” section of this final rule. In addition, recent events provide additional evidence of the potential for catastrophic events to further exacerbate extinction risks. In January 2009, significant mortality occurred to eggs of Penobscot origin at CBNFH. Low egg survival rates in the Penobscot population required the use of the domestic line for smolt production (50,000) for the first time ever. The relative fitness rate of the sea-run line has not been compared to the domestic line, so the demographic effects are unpredictable. The cause for the low egg survival rate is unknown, but is being investigated at the time of writing of this rule.

Comment 15:

Several commenters felt that by increasing the geographic scope of the GOM DPS to include additional populations, one being the Penobscot, which has the highest returns to the DPS, the extinction risk is substantially reduced. Therefore, these commenters felt that a threatened listing determination is warranted.

Response:

All things being equal, larger populations do have lower extinction risks. However, the inclusion of the Penobscot population in the GOM DPS does not alter the trends in abundance, which are pointing toward extinction. The addition of the Penobscot population does provide some measure of security from immediate extinction risks, but does not reverse the long-term trend which is toward extinction.

Comment 16:

At least one commenter argued that a threatened listing determination could be justified based upon the returns to both the Penobscot and Downeast Salmon Habitat Recovery Units (SHRU). These two SHRUs, according to the commenter, satisfy the minimum recovery criteria by having at

least 500 (naturally reared and hatchery origin) salmon within each SHRU.

Response:

In developing its draft recovery criteria for use in the critical habitat designation process, NMFS specifically noted that in order to be eligible for recovery, SHRUs would not only need to meet a minimum population size of 500 individuals, but also show a positive population growth rate for at least two generations (10 years). Further, only wild-origin salmon are included in these measures because the goal of recovery is to achieve a self-sustaining population; a population that relies on hatchery stocking is not self-sustaining and therefore does not contribute to achievement of the recovery criteria. These criteria have clearly not been met in either case given the long-term downward trends in abundance and preponderance of hatchery-origin salmon composing the GOM DPS as described throughout this final rule. NMFS' draft recovery guidelines (2008) also state that in order to delist the GOM DPS, the threats identified at the time of listing must be addressed.

Comment 17:

Many commenters argued that the PVA results of Legault (2004, 2005) and Fay

et al.

(2006), coupled with low returns and poor marine survival, demonstrate that the Services are correct in their proposal to list the GOM DPS as endangered under the ESA. These commenters felt that the intent behind the ESA is to recover wild populations and that hatchery origin fish are only a temporary option until the wild population recovers.

Response:

We concur. We also recognize the long-term risks of reliance on hatcheries that are not accounted for in either PVA. Therefore, we are issuing this final rule to list the GOM DPS of Atlantic salmon as endangered.

Comment 18:

A small number of commenters argued against listing the expanded GOM DPS at all. They argued that the rivers included in the expansion are heavily stocked and do not represent self-sustaining populations. They also stated that existing regulatory mechanisms are sufficiently protective, and thus, listing under the ESA is not necessary.

Response:

Many endangered species are currently not self-sustaining. In fact, this is a key factor in determining whether a species should be listed; self-sustaining populations are generally less likely to need the protection of the ESA, depending on the threats facing the species. The Services do recognize the long history of stocking to support Atlantic salmon recovery in Maine. We describe both the positive and negative effects of hatchery supplementation in the “Population Status of the GOM DPS” section of this final rule. The weight of the available genetic, life history, and ecological data clearly indicates that the GOM DPS (including conservation hatchery populations used to supplement natural populations) satisfies both the discreteness and significance criteria of the DPS Policy, and therefore, is a DPS. The fact that the GOM DPS is not self-sustaining with the existing regulatory mechanisms and is trending toward extinction indicates it warrants the protection of the ESA.

Comment 19:

Several commenters felt that the threat posed by dams was overstated. Specifically, they disagree with the Services' assertion that current fish passage technology results in a high level of mortality and that dams contribute to significant changes in fish assemblages and predation. One commenter stated that in focusing on the threat posed by dams, the Services failed to recognize hydropower as a clean source of energy production.

Response:

The Services disagree that the threat posed by dams is overstated. The National Research Council stated in 2004 that the greatest impediment to self-sustaining Atlantic salmon populations in Maine is obstructed fish passage and degraded habitat caused by dams. There are many studies that support this conclusion that are reviewed and cited in Section 8 of Fay

et al.

(2006). Dams result in direct loss of production habitat, alteration of hydrology and geomorphology, interruption of natural sediment and debris transport, and changes in temperature regimes (Wheaton

et al.,

2004). Riverine areas above impoundments are typically replaced by lacustrine habitat following construction. Dramatic changes to both upstream and downstream habitat directly result in changes in the composition of aquatic communities, predator/prey assemblages, and species composition (NRC, 2004; Fay

et al.,

2006; Holbrook, 2007). Upstream changes in habitat are known to create conditions that are ideal for known predators of Atlantic salmon such as chain pickerel, smallmouth bass, and avian predators like double crested comorants (Fay

et al.,

2006). Furthermore, dams not only change predator-prey assemblages, but dam passage also negatively affects predator detection and avoidance in salmonids (Raymond, 1979; Mesa, 1994). Adults may also be susceptible to predation when they are attempting to locate and pass an upstream passage facility at a dam when stressed by higher summer temperatures (Power and McCleave, 1980).

Even highly effective passage facilities cause Atlantic salmon mortality. Passage inefficiency and delays occur at biologically significant levels, resulting in incremental losses of pre-spawn adults, smolts, and kelts (a life stage after Atlantic salmon spawn). Dams are known to typically injure or kill between 10 and 30 percent of all fish entrained at turbines (EPRI, 1992). With rivers containing multiple hydropower dams, these cumulative losses could compromise entire year classes of Atlantic salmon. Studies in the Columbia River system have shown that fish generally take longer to pass a dam on a second attempt after fallback compared to the first (Bjornn

et al.,

1999). Thus, cumulative losses at passage facilities can be significant and are an important consideration.

The Services do recognize that hydropower does not contribute to air pollution as do many other energy sources. However, dams remain a direct and significant threat to Atlantic salmon.

Comment 20:

Several commenters stated that existing recreational fishing regulations in the State of Maine are sufficiently protective of Atlantic salmon. Specifically, minimum and maximum length limits are cited for landlocked salmon and brown trout, as well as gear restrictions, area closures, and outreach programs to educate anglers on identification and mandatory regulations. Several of these commenters highlighted the importance of the support of the angling community to the conservation and recovery effort. They encouraged the Services to coordinate with the angling community prior to enacting regulations to ensure that unnecessary regulations are not enacted and that angling opportunities are made available when biologically appropriate and that any changes are consistent with the

1996 Policy for Conserving Species Listed or Proposed for Listing Under the ESA While Providing and Enhancing Recreational Fishing Opportunities

. Several commenters directly stated that the health of the Penobscot population could indeed support a directed catch and release fishery.

Response:

There are a number of minimum and maximum length limits that help reduce the threat of take of juvenile and adult anadromous Atlantic salmon. Similarly, closures have been enforced in certain areas where anadromous Atlantic salmon may be particularly susceptible to take. However, the Services believe that many of these regulations are still not sufficiently protective of outmigrating smolts and of adults. Minimum and

maximum length limits should be adjusted to be more protective, specifically, the maximum length limit of 25 inches (63.5 cm) for landlocked salmon should be decreased to 16 inches (40.6 cm) in certain areas. Closures should be prompted by the presence of adult Atlantic salmon in certain areas such as thermal refugia, overwintering areas, and holding pools. Some closures mandated by the State have been the result of emergency action following the lethal take of Atlantic salmon. A proactive approach to closures and regulation implementation will be more effective in terms of salmon recovery.

The Services recognize that the angling community has lent significant support to the conservation and recovery of Atlantic salmon in the GOM DPS. We believe that we have been very inclusive and transparent with respect to the angling community and issues of concern. We invited representatives of angler organizations to participate as members of the Atlantic Salmon Recovery Team and have been engaged and participated in critical discussions in other forums such as the Maine Atlantic Salmon Technical Advisory Committee and NASCO. We will continue to coordinate and collaborate with the angling community as we move forward with recovery and management of the GOM DPS. We believe that we have been consistent with the

1996 Policy for Conserving Species Listed or Proposed for Listing Under the ESA while Providing and Enhancing Recreational Fishing Opportunities

in our communication and coordination with the angling community, and we will continue to be consistent in the future.

It is not biologically appropriate, at this time, to allow a directed catch and release fishery on the Penobscot River. The Atlantic salmon population in the Penobscot River is highly dependent on hatchery stocking; broodstock goals have not been met in most recent years; and the population is less than 10 percent of its spawning escapement target. Given these low numbers, it is important to meet broodstock goals and also to allow some returning adults to spawn naturally in the river. Decreasing the chances of reaching both of these goals by allowing targeted fishing on returning adults does not further the conservation of the species. There also are legal restrictions on targeted fishing for a listed species.

Comment 21:

Maine's Department of Inland Fish and Wildlife (MIFW) stocks a variety of fish species to provide angling opportunities to Maine citizens. The bulk of the comments on MIFW stocking programs were submitted as comments on Factor B (Overutilization for Commercial, Recreational, Scientific and Educational Purposes). While stocking programs do cause take of Atlantic salmon due to angling, they also can have a negative impact on Atlantic salmon due to competition, particularly from non-native species. Factor E (Other Natural or Manmade Factors Affecting Its Continued Existence) addresses the issue of competition. Thus, comments related to stocking and potential competition issues are addressed in the section of the response to comments under Factor E.

Comments that were directly related to the impact of stocking programs on Atlantic salmon as a result of the expansion or increase in angling opportunities cite coordination with the MDMR as evidence that measures are taken to minimize any harmful effects of stocking practices on Atlantic salmon. Commenters also stated that in some areas where the habitat is not fully seeded with Atlantic salmon, informal agreements between MDMR and MIFW have been reached to allow for a certain level of fish stocking to enhance angling opportunities without creating a significant threat to salmon that may be in the area. One commenter also cited guidelines that are in the process of being finalized that will be used to manage rainbow trout stocking. Several commenters disagree with the Services' conclusion that these stocking programs are harmful to Atlantic salmon.

Response:

MIFW stocking practices that create more angling opportunities in areas occupied or used by Atlantic salmon contribute to the potential for take to occur as a result of misidentification, bycatch, or poaching. MIFW stocking programs are not directed to Atlantic salmon recovery or ecosystem restoration. They are intended to create and enhance angling opportunities, and, where these overlap with salmon, there is increased risk to salmon. MIFW currently stocks landlocked Atlantic salmon, brown trout, brook trout, rainbow trout, and splake in Atlantic salmon drainages, posing a threat to Atlantic salmon in the GOM DPS (Fay

et al.,

2006). The information presented by commenters with respect to angling regulations and stocking program management does not change our conclusion that angling and stocking programs associated with increased angling opportunities pose an ongoing threat to Atlantic salmon in the GOM DPS. While coordination may reduce or minimize exposure of Atlantic salmon to increased angling pressure, the fact remains that angling pressure is higher than it would be in the absence of these stocking programs.

Comment 22:

One commenter was concerned that the text on the threat of disease did not reflect the State of Maine's effort to attain Class A fish health ratings for the hatcheries managed by MIFW.

Response:

The text has been changed to reflect the effort on behalf of the State of Maine to achieve the Class A fish health rating. With this effort, disease issues still pose a threat to Atlantic salmon as described in Factor C below.

Comment 23:

One commenter felt that the text in the predation threat analysis did not acknowledge the restoration efforts of the State of Maine, specifically the Penobscot River Multi-species Management Plan and the Penobscot Interagency Technical Committee.

Response:

The Services believe that these two conservation actions are more appropriately described and evaluated in the analysis of conservation efforts under the Policy for Evaluating Conservation Efforts. We have revised that analysis to incorporate information on both of these efforts.

Comment 24:

Many commenters disagree with the Services' conclusion that the regulatory mechanisms to address the threat posed by dams are inadequate. These commenters stated that a number of laws directly (

e.g.

, Federal Power Act (FPA)) and indirectly (

e.g.

, ESA, National Environmental Policy Act) allow Federal resource agencies to influence passage issues and hydropower agreements. They state that the Federal Energy Regulatory Commission (FERC) process is very transparent and allows for public involvement. For non-FERC dams, commenters cited the oversight of the State of Maine Department of Environmental Protection (MDEP) in addressing fish passage, flow regimes, and water quality.

Response:

Notwithstanding the ESA, the current state and Federal regulatory mechanisms in place to address operation of dams were not designed to address survival or recovery of endangered species. The Services recognize that there are a number of laws that create a process whereby industry, Federal resource agencies, the public, state agencies and other groups are involved in relicensing, brokering settlement agreements, or prescribing fish passage. However, as described in the section of this rule that addresses Factor D, there are substantial shortcomings associated with these processes. First, most of these processes require a “balancing” of energy and environmental resources. Under the ESA, deference is given to the species.

The FERC process is extremely lengthy, and any contentious fishway prescriptions could potentially take years to agree on and implement. Furthermore, neither upstream nor downstream fish passage measures are 100 percent efficient. Their limitations contribute to juvenile and adult injury and mortality, as well as habitat alterations that affect the health and survival of all life stages of Atlantic salmon. Sections 10(a) and 10(j) of the FPA could be used by the Services to address the impact of dams on habitat; however, these regulatory mechanisms are often discretionary and not necessarily required by FERC (Fay

et al.

, 2006). Section 4(e) of the FPA may also be used to recommend fisheries enhancements; however, this section is only applicable to certain Federal lands which are a rare occurrence in Maine (Fay

et al.

, 2006).

It is also important to recognize that, while settlement agreements can be a very useful tool to address passage issues, they are not necessarily removing the issue of passage mortality or in some cases, even ensuring passage facilities. For example, the Kennebec Hydro Developers Accord uses biological triggers to establish sequential upstream passage. If these biological triggers are not met, upstream passage could be suspended further into the future.

The majority of dams within the GOM DPS range do not require a FERC license or water quality certificate from the MDEP. These non-jurisdictional dams are usually small, non-generating dams that were historically used for flood control, water storage, and other purposes. Virtually none of these dams have fish passage facilities, and almost all of them are impacting historical salmon habitat. While there is a process whereby the public can petition the State of Maine to set minimum flows and water levels, the State has no authority to prescribe fishery enhancements without public request or petition. To our knowledge, no fishways have ever been installed at any dam in the State of Maine using the fishway petition process outlined pursuant to 12 Maine Revised Statutes Annotated (MRSA) § 12760. Therefore, significant issues are ongoing with respect to the current mechanisms in place to address the threat of both FERC and non-FERC licensed dams.

While regulations exist, these regulations have not proven effective in preventing impacts or quickly responding to remove impacts. In fact, the most progress on fish passage issues has been accomplished by working outside of these regulatory mechanisms in the negotiation of fish passage agreements. Aspects of the current regulations we find inadequate include the time delays experienced, extensive resource requirements, and inability to prescribe a solution which eliminates the impacts from dams.

Comment 25:

Some commenters stated that Maine's existing water quality standards and criteria and its antidegradation policy under the Clean Water Act (CWA) as administered by the State of Maine (Maine Pollutant Discharge Elimination System (MPDES)) are sufficiently protective of all life stages of Atlantic salmon. Furthermore, commenters state that lack of requests by the Services to condition permits to avoid substantial impairment to Atlantic salmon is evidence that the present standards and criteria are protective of Atlantic salmon.

Response:

Maine's water classification program, of which the State's antidegradation policy is a part, provides for different water quality standards for different classes of waters (

e.g.

, there are four classes for freshwater rivers, all of which are found within the GOM DPS range). Some portions of the GOM DPS are in the highest water quality classification where water quality standards are the most stringent. These standards become progressively less stringent with each lower water classification. These standards were not defined specifically for Atlantic salmon. Additionally, permits allow an area of initial dilution or mixing zone where water quality requirements are reduced. Salmon in or passing through such zones would be exposed to discharges below water quality standards.

Even where water quality standards are believed to be sufficiently protective when met, there are circumstances and conditions where discharges do not meet water quality standards. There are documented cases where minimum dissolved oxygen standards were not met in class C waters (MDEP, 2008). Adequate dissolved oxygen concentrations are necessary for fish health (Decola, 1970). The observed incidents of low dissolved oxygen were potentially harmful to any salmon present.

The fact that the Services have not requested that permits be conditioned to protect Atlantic salmon does not mean that water quality standards are sufficiently protective of Atlantic salmon. Currently, the Services review only permits that may affect salmon where listed in 2000, and the number of permits issued in this area has been relatively small. Expansion of the DPS as a result of this final rule will encompass rivers for which there are many more activities requiring Maine Pollutant Discharge Elimination System (MPDES) permits, and where water classifications and associated water quality standards are lower, which causes us to be concerned about potential impacts to salmon. See Factors A and D, below, for our analysis of the impact of water quality on the GOM DPS.

Comment 26:

Some commenters stated that we inaccurately emphasized the effects of Overboard Discharges (OBD) on Atlantic salmon. They explain that the number of OBDs, the volume of discharge, and the treatment requirements result in a negligible effect on water quality within the range of the GOM DPS.

Response:

In the proposed rule, we stated that we were concerned about the potential negative impacts of OBDs on water quality and identified OBDs as a threat to the GOM DPS. While we remain concerned about the potential for OBDs to impact Atlantic salmon, we have determined that we have insufficient information to determine whether OBDs are currently causing or will cause harm to the GOM DPS. Therefore, we have removed OBDs as an identified stressor under Factors A and D below.

Comment 27:

Commenters emphasized the importance of Maine's water rule (MDEP Chapter 587 Rule) in protecting in-stream flows and habitat for aquatic life.

Response:

We agree that the Water Rule represents substantial progress toward limiting negative impacts on in-stream flows due to water withdrawals, particularly for class AA waters. However, there are aspects of the water rule that are not sufficiently protective of Atlantic salmon. Because the flow standards for class A, B, and C waters are based on the seasonal base flow (the average flow over an entire season), withdrawals would be allowed that maintain flow above the seasonal base flow but reduce flow below the median monthly flow. During times when flows are naturally low, allowing withdrawals to reduce flows further, to levels below the median monthly flow, would negatively impact Atlantic salmon. See Factors A and D, below, for our analysis of the impacts of water withdrawals under Maine's water rule on the GOM DPS.

Comment 28:

Some commenters noted Maine's forestry-related regulations and standards that are protective of Atlantic salmon.

Response:

We concur that activities conducted in compliance with the Shoreland Zoning Act, Maine Forest

Practices Act, Natural Resource Protection Act, Protection and Improvement of Waters Act, Erosion and Sedimentation Control Law, and the Statewide Standards for Timber Harvesting and Related Activities in Shoreland Areas reduce threats to Atlantic salmon from sedimentation and other impacts related to forestry activities. The State's compliance monitoring and enforcement of these regulations and standards will assist in evaluating and confirming that forestry-related impacts to salmon are minimized. We discuss forestry activities and other potential non-point sources of pollution under Factors A and D below.

Comment 29:

Several commenters indicated that the threat of poor marine survival was understated. They felt that considering that poor marine survival was characterized as one of the primary threats to the GOM DPS, the Services have failed to adequately address it in either the proposed rule or the 2006 Status Review.

Response:

The Services agree and have incorporated additional information on marine survival into the final rule to properly reflect the significance of the threat of poor marine survival to the recovery of the GOM DPS. Marine survival and climate change are both addressed through analysis of the five factors specified in section 4(a)(1) of the ESA.

Comment 30:

One commenter disagreed with the identification of depleted diadromous fish communities as a threat to the GOM DPS. The commenter felt that the State of Maine is making strides in implementing management actions aimed at restoration of diadromous fish communities. These programs will need time to achieve success; however, the commenter argues that the threat need not be considered given that there are programs in place to address diadromous fish restoration.

Response:

The Services acknowledge the efforts by the State of Maine at diadromous species restoration in the analysis of State protective efforts. While the goal of these efforts is to restore the full suite of diadromous fishes, that goal is far from being realized. Further, there is not a high level of certainty that these actions will be implemented and effective. It is very encouraging that the role of restored diadromous fish communities is recognized; however, significant coordination, effort, and commitment are necessary to achieve the goal. Thus, the threat of depleted diadromous fish communities remains. The PECE analysis section of this rule contains the Services' evaluation of these programs as well as other conservation efforts.

Comment 31:

One commenter disagreed that MIFW sport fish stocking programs pose a threat to Atlantic salmon. These comments were submitted under Factor B, but in large part were directed at the way the Services characterized the threat of competition due to stocking under Factor E. The commenter stated that coordination between MIFW and MDMR is evidence that measures are taken to minimize any harmful effects of stocking practices on Atlantic salmon. In some areas where the habitat is not fully seeded with Atlantic salmon, informal agreements allow for a certain level of stocking without adversely affecting Atlantic salmon. The commenter also cited guidelines that are in the process of being finalized that will be used to manage rainbow trout stocking.

Response:

The Services disagree with the commenter that the threat posed by MIFW stocking programs is adequately addressed by the current stocking management program. Text has been added to the section of the rule that discusses competition to provide additional detail to clarify the negative impact current stocking programs have in terms of contributing to the threat of competition between other species and Atlantic salmon. The Services do recognize that a Memorandum of Understanding (MOU) exists between MDMR and MIFW that establishes a process for the management and stocking of freshwater salmonid fish species in Atlantic salmon river systems in Maine to “reduce the effects of competing finfish species on Atlantic salmon populations.” The MOU states that on an annual basis, at the very least, before April each year, biologists from MDMR and the MIFW will meet as a joint committee to: (1) Identify all current stocking programs for all finfish in identified Atlantic salmon river systems; (2) according to the best available scientific information on species interactions, assess the possible interactions between Atlantic salmon and inland fisheries management proposals; (3) identify and evaluate areas of concern and assess ways to minimize impacts; (4) implement agreed upon management actions or changes (no fish stocking or changes in management programs on these rivers shall take place other than in accordance with this agreement); and lastly, (5) develop recommendations for the Commissioner of Inland Fisheries & Wildlife and the other members of the Board of the Atlantic Salmon Commission for areas of concern that cannot be resolved by the joint committee. While this MOU does provide a process for managing stocking practices, it does not address all of the threats posed by the State's stocking practices. Some of the issues this process does not address include, but are not limited to, the following: (1) Cumulative effects of repeated stockings and multi-species stocking on Atlantic salmon; (2) competition for suitable over-wintering areas; (3) threats from introduction of parasites or disease from stocking; (4) the threats posed by Atlantic salmon/brown trout hybrids; and (5) management of other fish species (smallmouth bass, chain pickerel, etc.). Because these and other issues still have not been addressed fully, state stocking programs continue to pose a threat to the GOM DPS as is described in this rule.

Comment 32:

Several commenters felt that the Services did not give enough consideration to ongoing conservation efforts in the GOM DPS. Commenters used specific examples, including, but not limited to, the Penobscot River Restoration Project, the Kennebec Hydro Agreement, and Project SHARE (Salmon Habitat and River Enhancement). Many commenters felt that the PECE was not appropriately applied. Commenters suggested that the Services may need to use the PECE to reevaluate projects like the Penobscot River Restoration Project for which funding and certainty of implementation may have changed since publication of the proposed rule.

Response:

The Services agree that analysis of conservation efforts under PECE is more transparent if a more complete analysis of major efforts is included in the rule. We have revised the section addressing analysis of conservation efforts.

Comment 33:

Some commenters are concerned that having two Federal agencies (NMFS and USFWS) share jurisdiction of Atlantic salmon is inefficient, which is detrimental to the overall conservation of Atlantic salmon. As a result, some recommended that NMFS be assigned the lead Federal agency for management of Atlantic salmon.

Response:

Joint jurisdiction of Atlantic salmon was first established in 1994, when the Services worked together jointly to respond to a listing petition for Atlantic salmon. While we acknowledge that sharing jurisdiction for an endangered species is challenging, we believe that both agencies can contribute positively to recovery. Therefore, we will continue to share jurisdiction for Atlantic salmon. The goal of both agencies is the recovery of Atlantic salmon; to that end we will

strive to work cooperatively and effectively to conserve Atlantic salmon. To clarify roles and responsibilities of each agency and help resolve potential differences, we have developed a Statement of Cooperation (NMFS and USFWS, 2009). The preamble to this rule identifies how roles and responsibilities have been divided between the two agencies.

Comment 34:

Some commenters were concerned about the lack of resources to fulfill the requirements of the ESA for Federal agencies, the State, Tribes, or the regulated community as will be required by listing the Atlantic salmon in a larger area.

Response:

As required by section 4(b)(1)(A) of the ESA, listing decisions are to be made solely on the basis of the best scientific and commercial data available. We fully recognize that resources are limited and intend, through our collaborative partnership with the State and Tribes, to make most efficient use of our collective resources to conserve and recover Atlantic salmon. The challenge of addressing high workload with limited resources is one of the reasons the Services have divided responsibility for ESA implementation by activity as noted in the response above. We will work within the ESA's flexible framework to achieve the regulatory requirements of the ESA.

Comment 35:

Several commenters suggested that listing determinations should consider the likelihood of future cooperation and collaboration toward recovery.

Response:

Under the ESA, the Services must make each listing determination solely on the best available data on the status of the species, the five factors specified in section 4(a)(1) of the ESA, and the efforts being made to protect the species. The possibility of enhanced cooperation in future recovery actions is not one of the five statutory factors. While we recognize the importance of cooperation in achieving recovery, it is not one of the factors identified by the ESA for making listing determinations. Therefore, we have not considered it in this determination.

Summary of Factors Affecting the GOM DPS

Section 4 of the ESA (16 U.S.C. 1533) and implementing regulations at 50 CFR part 424 set forth procedures for adding species to the Federal List of Endangered and Threatened Species. Under section 4(a) of the ESA, we must determine if a species is threatened or endangered because of any of the following five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence.

We have described the effects of various factors leading to the decline of Atlantic salmon in previous listing determinations (60 FR 50530, September 29, 1995; 64 FR 62627, November 17, 1999; 65 FR 69459, November 17, 2000) and supporting documents (NMFS and USFWS, 1999; NMFS and USFWS, 2005). The reader is directed to section 8 of Fay

et al.

(2006) for a more detailed discussion of the factors affecting the GOM DPS. In making this finding, information regarding the status of the GOM DPS of Atlantic salmon is considered in relation to the five factors specified in section 4(a)(1) of the ESA.

In making this evaluation, we have carefully considered the relative demographic effects of each threat to the GOM DPS. In particular, there are large distinctions between marine survival and freshwater survival that are important to characterize the current status of the GOM DPS. From a demographic viewpoint, incremental increases in marine survival have a much greater impact on the population than do increases in freshwater survival; although, increases in marine survival may be more difficult to achieve. It is important to note that marine survival is calculated from the last time smolts are counted in a river until adults return to spawn. Thus, marine survival estimates may include some portion of freshwater, estuarine, and near-shore mortality in addition to open ocean mortality.

The historical range of freshwater survival for U.S. populations is estimated to be approximately 0.13 to 6.09 percent (Legault, 2005). These estimates are based on numerous studies on different life stages of the freshwater phase across a wide spatial and temporal scale. Current marine survival (smolt to adult) for U.S. populations is estimated to range from 0.09 to 1.02 percent based on total smolt cohort return rates for the Penobscot (hatchery smolt returns, 1995 to 2004) and Narraguagus Rivers (naturally reared smolt returns, 1997 to 2004) (ICES, 2008). For the reasons mentioned above, marine survival estimates of hatchery smolts in the Penobscot also include dam-related mortality.

Improvements in these survival rates are necessary to reach the point where each fish is replacing itself and to eventually result in population growth toward recovery. Increases in freshwater survival will enhance the probability of recovery; however, improvements in marine survival are necessary to achieve stability and growth. While numerous natural and anthropogenic factors during the freshwater phase influence Atlantic salmon populations (Baum

et al.

, 1983; McCormick

et al.

, 1998; Parrish

et al.

, 1998), the effects of marine survival are thought to have a greater influence on population levels (Friedland

et al.

, 2003; Jonsson and Jonsson, 2004; Chadwick, 1987) in part because the annual variation in marine survival is nearly four times greater than that in freshwater (Bley, 1987; Reddin

et al.

, 1988). Thus, marine survival has a significant impact on adult production. As a result, marine survival must improve in order to recover the GOM DPS (Legault, 2005), and, thus, low marine survival is one of the most important threats contributing to the poor status of the species. Other factors affecting the freshwater stages of salmon within the range of the GOM DPS can be quite pervasive (

e.g.

, poor connectivity due to improperly sized culverts). Below, these factors are described as stressors that collectively contribute to the poor status of the GOM DPS; however, those factors that affect later life stages (typically considered as marine survival) have the greatest demographic effect.

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

Changes to the GOM DPS's natural environment are ubiquitous. Both contemporary and historic land and water use practices such as damming of rivers, forestry, agriculture, urbanization, and water withdrawal have substantially altered Atlantic salmon habitat by: (1) Eliminating and degrading spawning and rearing habitat, (2) reducing habitat complexity and connectivity, (3) degrading water quality, and (4) altering water temperatures. These impacts and their effects on salmon are described in detail by Fay

et al.

(2006). Here, we summarize the stressors that are having the greatest impact on the GOM DPS.

Dams

Dams are among the leading causes of both historical declines and contemporary low abundance of the GOM DPS of Atlantic salmon (NRC, 2004). Dams directly limit access to otherwise suitable habitat. Prior to the construction of mainstem dams in the early 1800s, the upstream migrations of salmon extended well into headwaters

of large and small rivers alike, unless a naturally impassable waterfall existed. For example, Atlantic salmon were found throughout the West Branch of the Penobscot River (roughly 350 km inland) and as far as Grand Falls (roughly 235 km inland) on the Dead River in the Kennebec Drainage (Foster and Atkins, 1867; Atkins, 1870). Today, however, upstream passage for salmon on the West Branch of the Penobscot is nonexistent and on the Kennebec is limited to trapping and trucking salmon above the first mainstem dam. Dams also change hydraulic characteristics of rivers. These changes, combined with reduced, non-existent, or poor fish passage, influence fish community structure. Specifically, dams create slow-moving impoundments in formerly free-flowing reaches. Not only are these altered habitats less suitable for spawning and rearing of Atlantic salmon, they may also favor nonnative competitors such as smallmouth bass (

Micropterus dolomieu

) over native species such as brook trout (

Salvelinus fontinalis

) and American shad (

Alosa sapidissima

). Fish passage inefficiency also leads to direct mortality of Atlantic salmon, including both smolts and adults; these later life stages are particularly important from a demographic perspective as described above. Upstream passage effectiveness for anadromous fish species never reaches 100 percent, and substantial mortality and migration delays occur during downstream passage through screen impingement and turbine entrainment. The cumulative losses of smolts incrementally diminish the productive capacity of all freshwater rearing habitat above hydroelectric dams. The demographic consequences of low marine survival (described above) are similar to those of the cumulative losses of adults at dams. Comprehensive discussions of the impacts of dams are presented in sections 8.1, 8.3, and 8.5.4 of Fay

et al.

(2006) and NRC (2004).

In short, dams directly and substantially reduce survival rates of salmon through the following ways:

1. Dams directly limit access to otherwise suitable habitat. This has reduced spatial distribution of the GOM DPS over the last 200 years.

2. Dams also directly kill and injure a significant number of salmon on both upstream and downstream migrations. Injury and mortality due to dams occurs at the smolt and adult life stages. These older life stages are particularly important from a demographic perspective (similar to marine survival) since slight changes in survival rates at older life stages can drive demographic trends.

3. Dams also degrade the productive capacity of habitats upstream by inundating formerly free-flowing rivers, reducing water quality, and changing fish communities.

Dams are also one of three primary factors that led to the declining abundance trends that began in the 1800s. The other two factors (pollution and overfishing), though still operative, have been greatly reduced in severity (Moring, 2005). Dams, however, represent a significant threat during the current period of decline (1800s to present) and are generally more pervasive (over 300 within the freshwater range of the GOM DPS today) over that same time period. These effects have led to a situation where salmon abundance and distribution have been greatly reduced, and thus, the species is more vulnerable to extinction through processes such as demographic and environmental stochasticity, natural catastrophes, and genetic drift inherent in all small populations (Shaffer, 1981).

As stated above, dams directly limit access to otherwise suitable habitat, directly kill and injure a significant number of salmon during both upstream and downstream migration, and degrade the productive capacity of habitats upstream by inundating formerly free-flowing rivers, reducing water quality, and changing fish communities. Dams affect multiple life stages in multiple ways, particularly by preventing or impeding access to spawning habitat for returning adult salmon; impacts at this late life stage have the greatest demographic effect. Therefore, dams represent a significant threat to the survival and recovery of the GOM DPS.

Habitat Complexity

Some forest, agricultural, and other land use practices have reduced habitat complexity within the range of the GOM DPS of Atlantic salmon. Large woody debris (LWD) and large boulders are currently lacking from many rivers because of historical timber harvest practices. When present, LWD and large boulders create and maintain a diverse variety of habitat types. Large trees were harvested from riparian areas; this reduced the supply of LWD to channels. In addition, any LWD and large boulders that were in river channels were often removed in order to facilitate log drives. Historical forestry and agricultural practices were likely the cause of currently altered channel characteristics, such as width-to-depth ratios (

i.e.

, channels are wider and shallower today than they were historically). Channels with large width-to-depth ratios tend to experience more rapid water temperature fluctuations, which are stressful for salmon, particularly in the summer when temperatures are warmer. Further discussions of the impacts of reduced habitat complexity are presented in section 8.1.2 of Fay

et al.

(2006). Reduced habitat complexity acts as a stressor on the GOM DPS by reducing spaces for hiding from predators and increasing water temperature.

Habitat Connectivity

Over the last 200 years, habitat connectivity within the freshwater range of the GOM DPS has been reduced because of dams and poorly designed road crossings. Further discussions of the impacts of reduced habitat connectivity are presented in section 8.1.2 of Fay

et al.

(2006). As a highly migratory species, Atlantic salmon requ

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