23376 Federal Register / Vol. 74, No. 95 / Tuesday, May 19, 2009 / Proposed Rules 

DISPUTES (UTILITY CONTRACTS) 

(DATE) 

The requirements of the Disputes clause at 

FAR 52.233–1 are supplemented to provide 

that matters involving the interpretation of 

tariffed retail rates, tariff rate schedules, and 

tariffed terms provided under this contract 

are subject to the jurisdiction and regulation 

of the utility rate commission having 

jurisdiction. 

(End of clause) 

[FR Doc. E9–11654 Filed 5–18–09; 8:45 am] 

BILLING CODE 6820–61–S 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[FWS–R3–ES–2008–0030; 92210–1111– 

0000–FY09–B3] 

Endangered and Threatened Wildlife 

and Plants; 12-Month Finding on a 

Petition To List the Coaster Brook 

Trout as Endangered 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Notice of 12-month petition 

finding. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), announce a 

12-month finding on a petition to list 

the coaster brook trout (Salvelinus 

fontinalis) as endangered under the 

Endangered Species Act of 1973, as 

amended (Act). The petition also asked 

that critical habitat be designated for the 

species. After review of all available 

scientific and commercial information, 

we find that the coaster brook trout is 

not a listable entity under the Act, and 

therefore, listing is not warranted. We 

ask the public to continue to submit to 

us any new information that becomes 

available concerning the taxonomy, 

biology, ecology, and status of coaster 

brook trout and to support cooperative 

conservation of coaster brook trout 

within its historical range in the Great 

Lakes. 

DATES: The finding announced in this 

document was made on May 19, 2009. 

ADDRESSES: This finding is available on 

the Internet at http:// 

www.regulations.gov at Docket Number 

[FWS–R3–ES–2008–0030]. Supporting 

documentation for this finding is 

available for inspection, by 

appointment, during normal business 

hours at the U.S. Fish and Wildlife 

Service, Region 3 Fish and Wildlife 

Service Regional Office, 1 Federal Drive, 

Bishop Henry Whipple Federal 

Building, Fort Snelling, MN 55111. 

Please submit any new information, 

materials, comments, or questions 

concerning this finding to the above 

address, Attention: Coaster brook trout. 

FOR FURTHER INFORMATION CONTACT: 

Jessica Hogrefe, Region 3 Fish and 

Wildlife Service Regional Office (see 

ADDRESSES) (telephone 612–713–5346; 

facsimile 612–713–5292). Persons who 

use a telecommunications device for the 

deaf (TDD) may call the Federal 

Information Relay Service (FIRS) at 

800–877–8339. 

SUPPLEMENTARY INFORMATION: 

Background 

Section 4(b)(3)(B) of the Act (16 

U.S.C. 1531 et seq.) requires that, for 

any petition to revise the Lists of 

Endangered and Threatened Wildlife 

and Plants that contains substantial 

scientific and commercial information 

that listing may be warranted, we make 

a finding within 12 months of the date 

of our receipt of the petition on whether 

the petitioned action is: (a) Not 

warranted, (b) warranted, or (c) 

warranted, but the immediate proposal 

of a regulation implementing the 

petitioned action is precluded by other 

pending proposals to determine whether 

species are threatened or endangered, 

and expeditious progress is being made 

to add or remove qualified species from 

the List of Endangered and Threatened 

Species. Section 4(b)(3)(C) of the Act 

requires that we treat a petition for 

which the requested action is found to 

be warranted but precluded as though 

resubmitted on the date of such finding, 

that is, requiring that we make a 

subsequent finding within 12 months. 

Such 12-month findings must be 

published in the Federal Register. This 

notice constitutes our 12-month finding 

for the petition to list the U.S. 

population of coaster brook trout. 

Previous Federal Action 

The Sierra Club Mackinac Chapter, 

Huron Mountain Club, and Marvin J. 

Roberson filed a petition, dated 

February 22, 2006, with the Secretary of 

the Interior to list as endangered the 

‘‘naturally spawning anadromous (lakerun) coaster brook trout throughout its 

known historic range in the 

conterminous United States’’ and to 

designate critical habitat under the Act. 

The petition clearly identified itself as 

such and included the requisite 

identification information for the 

petitioners, as required in 50 CFR 

424.14(a). On behalf of the petitioners, 

Peter Kryn Dykema, Secretary of the 

Huron Mountain Club, submitted 

supplemental information, dated May 

23, 2006, in support of the original 

petition. This supplemental information 

provided further information on the 

species’ status and biology, particularly 

for brook trout in the Salmon Trout 

River. 

On September 13, 2007, we received 

a 60-day notice of intent to sue over the 

Service’s failure to determine, within 1 

year of receiving the petition, whether 

the coaster brook trout warrants listing. 

Under section 4 of the Act, the Service 

is to make a finding, to the maximum 

extent practicable within 90 days of 

receiving a petition, that it does or does 

not present substantial scientific or 

commercial information indicating that 

the petitioned action may be warranted. 

Further, the Act requires that, within 12 

months of receiving a petition found to 

present substantial information, the 

Service must determine whether the 

petitioned action is warranted. A 

complaint was filed in U.S. District 

Court in the District of Columbia on 

December 17, 2007, for failure to make 

a timely finding (Sierra Club, et al. v. 

Kempthorne, No. 1:07–cv–02261 (D.D.C. 

December 17, 2007)). The Service 

reached a negotiated settlement with the 

plaintiffs to submit the 90-day finding to 

the Federal Register by March 15, 2008. 

We published a ‘‘substantial’’ 90-day 

finding March 20, 2008. The negotiated 

settlement further required the Service 

to publish the 12-month finding in the 

Federal Register by December 15, 2008. 

The deadline for the 12-month finding 

was extended to April 15, 2009, by 

mutual consent. On April 15, 2009, we 

filed an unopposed motion to extend 

the deadline for the coaster brook trout 

12-month finding to May 12, 2009. 

Species Information 

Species Description 

Brook trout (Salvelinus fontinalis), 

also called brook char or speckled trout, 

is one of three species in the genus 

Salvelinus (chars) native to north and 

eastern North America; the others being 

lake trout (S. namaycush) and Arctic 

char (S. alpinus). The chars are a subgroup of fishes in the salmon and trout 

subfamily (Salmoninae) that is distinct 

from the ‘‘true’’ trout and salmon subgroups. 

The brook trout throughout its range 

in eastern North America exhibits 

considerable variation in growth rate, 

color, and other features, but generally 

can be distinguished from other char 

and trout species by its olive-green to 

dark brown back with a light yellowbrown vermiculate pattern, sides with 

large yellow-brown spots and blue halos 

surrounding small, sporadic red and 

orange spots. Pectoral, pelvic, anal, and 

lower caudal fin have leading edges of 

white bordered by black with the 


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remainder predominantly reddish to 

orange. Sea-run brook trout become 

silver with purple iridescence and show 

red spots on the sides (Scott and 

Crossman 1973, p. 208). 

Distribution 

The historical range of native brook 

trout extends along Hudson Bay in 

Canada across the Provinces of 

Manitoba, Ontario and Quebec, to 

Newfoundland and Labrador and south 

to Nova Scotia and New Brunswick in 

Canada; and from eastern Iowa through 

northern Illinois, northern Ohio, and the 

Great Lakes drainage (Minnesota, 

Michigan, Wisconsin), through the New 

England States (New York, New 

Hampshire, Vermont, Maine, 

Massachusetts, Pennsylvania, New 

Jersey), large New England rivers (such 

as the Hudson River and Connecticut 

River), and through the Appalachian 

Mountains in Maryland, Virginia, West 

Virginia, North Carolina, South 

Carolina, Tennessee, south to Georgia 

(MacCrimmon and Campbell 1969, pp. 

1700–1702; MacCrimmon et al. 1971, p. 

452; Scott and Crossman 1973, pp. 209– 

210; Power 1980, p. 142). Naturalized 

populations of brook trout were 

established as early as the late 1800s 

beyond the historical native range by 

introductions to waters in western 

North America, South America, Eurasia, 

Africa, and New Zealand (MacCrimmon 

and Campbell 1969, p. 1699, pp. 1703– 

1717). The current range of native brook 

trout still extends through Canada and 

down to Georgia in the U.S., but in 

many locations, populations have been 

completely extirpated or have 

contracted within this range towards 

upper stream reaches, higher altitudes, 

or headwaters (EBJV 2006, p. 2). 

Distribution of Brook Trout in the Great 

Lakes 

According to Bailey and Smith (1981, 

p. 1549) and MacCrimmon and 

Campbell (1969, p. 1701), brook trout 

are native to the lakes and tributaries of 

Lakes Superior, Huron, Michigan, and 

the tributaries of Lakes Erie and Ontario. 

Brook trout are not believed to have 

been present in Minnesota streams 

above barrier falls to Lake Superior 

(Smith and Moyle 1944, p. 119) or 

throughout most of the lower peninsula 

of Michigan (MIDNR 2008a, pp. 1–2; 

MacCrimmon and Campbell 1969, p. 

1704). 

Habitat Requirements 

Brook trout require clear, cold, welloxygenated water to thrive. They are 

generally found in water ranging 

between 41–68° Fahrenheit (5–20° 

Celsius), with their likely preferred 

temperature falling near the middle of 

this range (Power 1980, p. 172). Thermal 

requirements within this range vary by 

life cycle phase and season (Scott and 

Crossman 1973, p. 211; Blanchfield and 

Ridgway 1997, p. 750; Baril and Magnan 

2002, pp. 177–178). 

The brook trout spawns in late 

summer or autumn, the date varying 

with latitude and temperature. 

Spawning takes place most often over 

gravel beds but may be successfully 

accomplished over a variety of 

substrates if there is spring upwelling or 

a moderate current (Scott and Crossman 

1973, p. 210). Power (1980, p. 151) 

describes rangewide brook trout 

spawning, which occurs in the fall, 

when day length and temperature are 

decreasing. In northerly regions and at 

high elevations, brook trout may spawn 

as early as late August and spawning 

may be delayed until December in 

southern areas. As is typical for 

salmonids, females prepare redds 

(hollows scooped out for spawning) in 

suitable gravel substrate. The female 

then deposits her eggs in the redd where 

they are fertilized by a male. After 

spawning there is no further parental 

involvement with the young. The redd 

protects the eggs and allows an adequate 

exchange of dissolved gases and other 

materials during development. 

Brook trout are carnivorous, feeding 

opportunistically upon a variety of prey, 

such as worms, leeches, crustaceans, 

aquatic insects, terrestrial insects, 

spiders, mollusks, and fish (Scott and 

Crossman 1973, p. 212). Anadromous 

(migrating from salt water to spawn in 

fresh water) forms vary their feeding 

behavior and prey items based on their 

age and the environment, marine or 

riverine, they are occupying (Newman 

and Dubois 1997, p. 9). Brook trout also 

show diverse foraging behaviors; some 

individuals may be sedentary, eating 

crustaceans from the lower portion of 

the water column, whereas others in the 

same system may be more active and eat 

insects from the upper portion of the 

water column (McLaughlin et al. 1999, 

p. 386). This resource polymorphism 

may play a supplementary role in the 

extensive adaptive radiation (evolution 

of ecological variability within a rapidly 

multiplying lineage; Smith and 

Sku ́lason 1996) observed in this species. 

Genetics of Brook Trout 

A large amount of genetic variation for 

brook trout is distributed among populations 

(large Fst values). This pattern is heavily 

influenced by the diverse ecological and lifehistory characteristics of brook trout 

populations (population connectivity or 

isolation, philopatric tendency). This pattern 

of highly differentiated populations of brook 

trout is found at small and large geographic 

scales. Population genetic structuring is 

common in brook trout throughout its range 

(Angers et al. 1999, pp. 1049–1050). Like 

many salmonids, brook trout tend to have a 

hierarchical population structure resulting 

from the hierarchical design of the networks 

of streams and lake or coastal areas in which 

they live, and a complicated life cycle that 

leads to strong local adaptations. Taxonomic 

resolution can be even more complicated at 

the lake level when lakes include sympatric 

(occupying the same or overlapping 

geographic area without interbreeding) but 

genetically divergent brook trout populations 

such as in Lake Mistassini in Canada (Fraser 

and Bernatchez 2008, p. 1197). This degree 

of genetic divergence that forms among 

populations is reflective of the reproductive 

connections (isolation) among the 

populations across the range of the taxon. 

Six distinct genetic mitochondrial 

(mtDNA) clades have been identified 

throughout the range of brook trout in 

eastern North America (Danzmann et al. 

1998, p. 1307). These mtDNA clades 

reflect historical isolation in glacial 

refugia or long periods of isolation in 

nonglacial areas in the southern part of 

the species’ range. The Wisconsin 

glacial advance which covered portions 

of Canada covered all five Great Lakes 

15,000 years ago (Bailey and Smith 

1981, p. 1543). As these glaciers 

receded, brook trout recolonized the 

lakes from the Mississippi and Atlantic 

refugia (Danzmann et al. 1998, pp. 1308, 

1312). Given this pattern of glaciation, 

genetic diversity is greatest at the 

southern portion of the species’ range 

and gradually decreases northward 

(Danzmann et al. 1998, pp. 1310–1311). 

As the most geographically isolated (for 

tens of thousands of years), brook trout 

in the southern part of the species’ range 

(along the Appalachian Mountains 

south to Georgia) are the most diverse, 

containing all six mtDNA clades. The 

Great Lakes contains three of the six 

mtDNA clades. Throughout the northern 

portion of their range in Canada, brook 

trout are the least genetically diverse, 

with only a single mtDNA clade present. 

Within each of these lineages, there is 

evidence to suggest that selection is 

driving rapid phenotypic divergence in 

some populations. 

Results based on microsatellite DNA 

variation identified nine distinct genetic 

assemblages of brook trout in the U.S. 

(King 2009, unpub. data). Assemblages 

from the nonglacial southern part of the 

species’ range (along the Appalachian 

Mountains from Pennsylvania to 

Georgia) in the U.S. are the most 

genetically divergent, and this 

divergence among the assemblages 

generally decreases as the range 

progresses northward. 


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Genetics of Brook Trout in the Great 

Lakes 

Populations from Lake Superior and 

tributaries to Lake Erie form two of the 

nine genetic assemblages of brook trout 

in the U.S. The Lake Erie populations 

are the most divergent assemblage from 

the northern part of the species’ range. 

Lake Superior populations are similar in 

the degree of genetic divergence to the 

remaining northern assemblages 

grouping with the average genetic 

distance between brook trout 

populations in the U.S. Samples from 

the rest of the Great Lakes were not 

available for analysis. Although brook 

trout in the Great Lakes do not contain 

any wholly unique mtDNA clades, they 

do contain a large amount of the genetic 

variation in a confined portion of the 

range (Danzmann et al. 1998, pp. 1310– 

1311). 

Native populations of brook trout in 

Lake Superior in most cases have 

retained their native genetic 

characteristics despite the stocking of 

hatchery fish from sources outside and 

within the Lake Superior basin. In Lake 

Superior, the intensity and purpose of 

stocking has varied over time and space. 

For example, Minnesota tributaries to 

Lake Superior have been stocked with 

hatchery strains that originated from 

outside of the Great Lakes Basin to 

provide fishing opportunities above fish 

passage barriers (Wilson et al. 2008, p. 

1312). Until the early 1990s, most of the 

stocked fish in Lake Superior were 

domesticated strains from outside the 

Great Lakes basin (Schreiner et al. 2008, 

p. 1357), although many stocking events 

were undocumented and records of 

early stocking events are incomplete 

(Wilson et al. 2008, p. 1312). These 

stocking efforts were not targeted at 

rehabilitation and from that perspective, 

results were poor. The stocked fish were 

not behaviorally or evolutionarily 

adapted to the environment in which 

they were planted, criteria known to 

limit survival and reproductive success 

(Schreiner et al. 2008, p. 1357). 

Burnham-Curtis (2001, p. 2) concluded 

that hatchery fish have had little 

reproductive success in Lake Superior 

streams based on her examination of 36 

tributaries to Lake Superior and 9 

hatchery stocks outplanted into the lake. 

However, the genetic methods used by 

Burnham-Curtis provided low power to 

detect genetic introgression of hatchery 

fish into native populations (Wilson et 

al. 2008, p. 1312). A recent study by 

D’Amelio and Wilson (2008, p. 1215) 

used genetic methods with high power 

to detect genetic introgression of 

hatchery fish into natural populations. 

This study documented only low levels 

of genetic introgression of Lake Nipigon 

hatchery fish into native populations of 

brook trout from six tributaries to Lake 

Superior’s Nipigon Bay (D’Amelio and 

Wilson 2008, p. 1222), despite decades 

of stocking. A study by Scribner et al. 

(2006, pp. 3–4) examined nine brook 

trout populations from Lake Superior 

tributaries on the south shore of 

Michigan and four hatchery strains 

outplanted into those tributaries. This 

study used similar methods to D’Amelio 

and Wilson (2008). Scribner et al. (2006, 

p. 8) concluded that hatchery stocking 

appears to have minimal if any impact 

of on brook trout. 

Brook Trout Life-History Diversity 

An individual’s ability to produce 

multiple phenotypes (visible or 

observable characteristics) in response 

to its environment is termed phenotypic 

plasticity (Scheiner 1993, p. 36). Recent 

studies have recognized the role of 

phenotypic plasticity as a major source 

of phenotypic variation in natural 

populations (Price et al. 2003, p. 1438). 

The brook trout exhibits remarkable 

phenotypic plasticity across its natural 

range. This plasticity allows it to thrive 

in a variety of environments, from cold 

subarctic regions, through temperate 

zones and in southern refugia in eastern 

North America, and in a range of places 

where it has been introduced (Power 

1980, p. 142). Although primarily a 

stream-dwelling species, brook trout 

also occupy inland lakes and coastal 

waters. Because of the variety of the 

freshwater, estuary, and ocean 

environments, migratory plasticity is 

also favored. The brook trout’s dispersal 

subsequent to receding glaciation, and 

separation into isolated breeding stocks 

in diverse habitats subject to an array of 

natural and man-made influences have 

all contributed to this variability (Power 

1980, p. 142). 

Brook trout display considerable lifehistory variation throughout their native 

range (Huckins and Baker 2008, p. 

1229). Brook trout across its range 

exhibit a variety of life-history types 

(polymorphisms or ecotypes), including 

fluvial (stream-dwelling), adfluvial 

(migrating between lakes and streams), 

lacustrine (lake-dwelling), and 

anadromous (migrating from salt water 

to spawn in fresh water) forms. 

Understanding life-history diversity in a 

species requires knowledge of the 

evolutionary history, ecological setting, 

and reproductive relationships among 

ecotypes. Reproductive interactions 

between ecotypes are reflected by the 

magnitude and pattern of genetic 

differentiation observed between lifehistory phenotypes at neutral genetic 

markers. The expression of migratory 

behavior (expressed as the adfluvial and 

anadromous ecotypes) by any 

individual fish will be partially in direct 

response to its environment. Phenotypic 

expression of more than one form may 

be expected in a population located in 

a variable environment containing 

habitats for several ecotypes. The 

amount of phenotypic plasticity a 

population will exhibit for the migratory 

trait also has a heritable genetic basis 

and will be determined by the intensity 

and type of selective pressures that 

population experiences (Via and Lande 

1985, pp. 517–519; Theriault et al. 2008, 

pp. 418–419). 

Adoption of migratory adfluvial form 

or stream-resident life-history form in 

brook trout has been modeled under a 

conditional strategy framework where 

environmentally influenced threshold 

traits determine which ecotype a fish 

will adopt (Hendry et al. 2004, pp. 124– 

125). Growth rate efficiencies, body size, 

and concentration of juvenile hormone 

have all been identified as potential 

threshold traits (Theriault and Dodson 

2003, pp. 1155–1157). Theoretical work 

by Ridgway (2008, p. 1185) and Uller 

(2008, pp. 436–437) also provide 

information to suggest parental effects 

are important to the expression of 

alternate ecotypes of brook trout. These 

parental effects describe an affect of the 

parental phenotype on the offspring’s 

phenotype such as coaster females 

producing larger eggs and spawning in 

different locations from stream-resident 

ecotypes, influencing the habitat use 

(Morinville and Rasmussen 2006, pp. 

701–702) and growth rate at the juvenile 

stage (Perry et al. 2005, p. 1358). These 

differences in growth rate and habitat 

use impact potential threshold traits. 

Work on sympatric brook trout life 

forms at young ages largely comes from 

a few studies on anadromous 

populations. Morinville and Rasmussen 

(2003) studied the bioenergetics of 

young brook trout exhibiting 

anadromous migratory and streamresident life tactics. They found that the 

anadromous migrants have higher 

metabolic costs and had consumption 

rates 1.4 times that of stream residents 

but growth efficiencies of the 

anadromous form were lower than that 

of residents. Spatial utilization of 

habitat differed among the life tactics as 

well, with migratory individuals 

occupying faster-flowing waters 

compared to the resident fish which 

used pool areas (p. 408). They 

concluded that migrant brook trout have 

noticeably different energy budgets than 

resident brook trout from the same 

system (p. 406). Morinville and 

Rasmussen (2008) also investigated 

morphological differences between life 


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tactics. The authors concluded that 

migrant brook trout were found to be 

more streamlined (narrower and 

shallower bodies) than resident brook 

trout, and these differences persisted 

into the marine life of the migrant fish 

(pp. 175, 183). The differences were 

powerful enough to derive discriminant 

functions using five of the measured 

traits allowing for accurate classification 

of juvenile brook trout as either migrant 

or resident with an overall correct 

classification rate of 87 percent. 

A study by Theriault et al. (2007b, p. 

61) found that sympatric anadromous 

and fluvial brook trout in the SainteMarguerite River in Quebec belonged to 

a single gene pool. Phenotypic plasticity 

is, therefore, a major force driving the 

expression of these two life histories 

from this population. Evolution of 

phenotypic plasticity in this population 

was influenced by mating systems with 

most of the mating between different 

morphotypes occurring between fluvial 

males and anadromous females. 

Additional work in this system 

demonstrated significant heritability for 

life-history tactic and for body size 

(Theriault et al. 2007a, pp. 7–8) 

indicating expression of life-history 

tactic in this population can be effected 

by natural or artificial selection. 

Life-History Diversity in Great Lakes 

Brook Trout 

Fish that complete their life cycle 

exclusively in tributaries to the Great 

Lakes exhibit the fluvial life history and 

are defined as stream residents. 

‘‘Coaster’’ (the subject of the petition) is 

a regional term for a life-history variant 

of brook trout in the Great Lakes 

(Burnham-Curtis 2001, p. 2; Wilson et 

al. 2008, p. 1) which use lake waters of 

the Great Lakes for all or a portion of its 

life cycle (Becker 1983, p. 320). The 

coaster form can be further divided into 

an adfluvial ecotype that migrates from 

the stream to the lake and back into 

tributaries to spawn and a lacustrine 

ecotype that completes its life cycle 

entirely within the lake (Huckins et al. 

2008, p. 1323). In the Great Lakes 

region, spawning usually occurs from 

mid-September through mid-November. 

Distinct life histories associated with 

the coaster and stream-resident types 

result in different physical, 

demographic, and ecological 

characteristics for the forms (Huckins et 

al. 2008, p. 1337; Huckins and Baker 

2008, p. 1241; Ridgway 2008, p. 1185). 

Specifically, coasters tend to live longer 

than stream residents (5–8 years versus 

less than 5 years), reach maturation later 

(females at 2–4 years versus 1–2 years), 

attain larger length and weight as adults 

(12–25 inches and 0.75–8 pounds (30– 

64 centimeters (cm) and 341–3632 

grams (g)) versus (5–15 inches (13–38 

cm) and (less than 1 pound (<454 g), be 

more fecund (1500–3000 eggs per 

female versus 100–1500 eggs per 

female), and move greater distances (up 

to 19–217 miles (30–350 kilometers 

(km)) versus less than 19 miles (30 km)) 

(Scott and Crossman 1973, pp. 208, 210, 

211; Power 1980, p. 157; Becker 1983, 

pp. 318, 320; Ritchie and Black 1988, 

pp. 19, 50, 51; Quinlan 1999, pp. 11, 12, 

14, 16, 17, 20; Swainson 2001, pp. 40, 

41, 60, 64; WIDNR and USFWS 2005, p. 

16; Huckins and Baker 2008, pp. 1239, 

1241; Huckins et al. 2008, pp. 1328, 

1329, 1337; Mucha and Mackereth 2008, 

p. 1210; Schram 2008a, pers. comm.; 

Chase 2008, pers. comm.). 

Coasters have been historically 

documented in Lakes Superior, Huron, 

and Michigan brook trout populations 

(Bailey and Smith 1981, p. 1549; 

Dehring and Krueger 1985, p. 1; 

Enterline 2000, p. 1; MIDNR 2008a, pp. 

1–2). However, Lake Superior is the 

only Great Lake with extant coaster 

forms of brook trout, and all available 

literature is from this area. Coasters in 

the Great Lakes are found in Canada and 

the U.S. in substantially fewer locations 

than they were historically (Newman et 

al. 2003, p. 39). Populations in the Great 

Lakes basin with these life-history forms 

are documented within Canada in 

tributaries to Nipigon and Black Bays, 

the Nipigon River, Lake Nipigon and the 

Pancake River in the eastern part of 

Lake Superior (Newman et al. 2003, p. 

39; Chase and Swainson 2009, pers. 

comm.). Within the U.S. portion of the 

Great Lakes basin, populations that 

express the coaster form occur in Isle 

Royale National Park in Tobin Harbor, 

Big and Little Siskiwit Rivers, and 

Washington Creek as well as on the 

south shore of Lake Superior in the 

Salmon Trout River (Newman et al. 

2003, p. 39). 

As previously stated, brook trout 

populations within the upper Great 

Lakes exhibit fluvial, adfluvial, and 

lacustrine life-history forms, coasters 

comprising the latter two forms. 

Populations of brook trout in Lake 

Superior likely function as types of 

metapopulations, with the coaster life 

forms serving as dispersers (D’Amelio 

and Wilson 2008, p. 1222; Sloss et al. 

2008, p. 1249). The viability of a 

metapopulation is strongly contingent 

upon maintaining dispersal among 

populations. Although brook trout 

exhibit spawning site fidelity, 

individuals exhibiting the adfluvial life 

forms in Lake Superior have also been 

shown to stray or disperse among 

streams (D’Amelio and Wilson 2008, p. 

1222; Mucha and Mackereth, p. 1211). 

The long-term persistence of a 

metapopulation requires a balance 

between local extinction and 

recolonization of constituent 

populations (see Hanski 1998 for a 

review of metapopulations). Dispersing 

individuals offset local population 

extinction by providing a means for 

recolonization (Brown and KodricBrown 1977, p. 448; Reeves et al. 1995, 

p. 340). Dispersing individuals also 

provide for gene flow among discrete 

populations, countering losses of 

genetic fitness while still allowing the 

development and distribution of unique 

adaptive traits (Ingvarsson 2001, p. 63; 

Tallmon et al. 2004, p. 494). Thus, the 

coaster life-history forms are important 

to the long-term viability of brook trout 

populations throughout Lake Superior. 

Genetic studies of stream-resident 

(fluvial life form) brook trout show 

substantial genetic structuring among 

populations in Michigan, Wisconsin, 

Minnesota, and Canada characterized by 

distinct regional groupings or 

metapopulations (Burnham-Curtis 1996, 

pp. 10–11; Burnham-Curtis 2001, p. 10; 

Sloss et al. 2008, p. 1249; Wilson et al. 

2008, p. 1312; Scribner et al. 2008, p. 9). 

In studies aimed at determining genetic 

differences between the coaster 

polymorphism and stream-resident fish 

occupying tributaries connected to the 

lake, molecular genetic work in Lake 

Superior indicates that coasters and 

stream-resident brook trout occupying 

tributaries to the first barrier are parts of 

the same population (D’Amelio and 

Wilson. 2008, p. 1221; Scribner et al. 

2008, p. 9; Stott 2008, p. 5). Work 

investigating the genetic differences of 

various tributaries to the lake found 

distinct differences among populations 

of brook trout in each tributary to Lake 

Superior (Burnham-Curtis 1996, p. 10; 

Burnham-Curtis 2000, p. 7; BurnhamCurtis 2001, p. 10; D’Amelio and Wilson 

2008, p. 1222; Sloss et al. 2008, p. 1249; 

Scribner et al. 2008, p. 9). Within Lake 

Superior, regional genetic differences 

are evident between brook trout 

populations in Nipigon Bay, Isle Royale, 

and Lake Nipigon-Grand Portage 

(Wilson et al. 2008, p. 1313). Adfluvial 

brook trout are thought to be the 

mechanism providing genetic 

communication among these regional 

aggregations and straying of a coaster 

was documented in Nipigon Bay and at 

Isle Royale (D’Amelio et al. 2008, p. 

1347; Stott 2008, p. 4). Sloss et al. (2008) 

investigated genetic differentiation 

among four Wisconsin populations of 

stream-resident brook trout. His work 

found significant differentiation among 

populations to the point the authors 

observed that for these populations, 


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there appears to be a near complete lack 

of gene flow among them resulting in 

genetic drift (Sloss et al. 2008, p. 1249). 

None of these isolated populations are 

thought to currently have adfluvial 

ecotypes as part of the population. This 

observation is consistent with the 

contemporary lack of an adfluvial form 

that historically provided the regional 

genetic connection for the three 

metapopulations previously mentioned. 

As characterized in the entire brook 

trout species, phenotypic plasticity and 

adaptive radiation (Schluter 2000, p. 1) 

appear to represent the continuum of 

evolutionary processes underlying the 

expression of life-history variation in 

populations of brook trout in Lake 

Superior (Ardren 2008, pp. 1–2). As 

stated above, plastic responses allow 

individuals to obtain high fitness in new 

environments. Alternatively, adaptive 

genetic differentiation among 

populations may provide evolutionary 

advantages. First, there are fitness costs 

to being highly plastic. For example, 

plastic genotypes need to maintain 

sensory and developmental pathways in 

order to induce plastic responses that 

are not required by nonplastic 

genotypes (Relyea 2002, pp. 272–273). 

Secondly, if the plastic response to a 

new environment is insufficient and 

directional selection favors an extreme 

phenotype, there will be genetic 

evolution of the trait (adaptive 

radiation). Therefore, if a population of 

brook trout experiences divergent 

selection in stable environments, we 

would expect the ecotypes to evolve 

genetic differences and nonplastic forms 

because the cost of maintaining the 

phenotypic plasticity would be too high. 

Findings in the Salmon Trout River 

indicate phenotypic plasticity plays a 

major role in the expression of the 

adfluvial and fluvial ecotypes while 

information from Isle Royale indicates 

adaptive radiation has occurred 

separating adfluvial and lacustrine 

coaster ecotypes. Migratory plasticity 

could be favored in situations where 

adfluvial and stream-resident brook 

trout co-occur because the environments 

they occupy are highly variable 

(Huckins et al. 2008, p. 1324; Ridgway 

2008, pp. 1186–1187). The alternating 

selection patterns associated with these 

diverse and variable environments 

create a fitness advantage for plastic 

genotypes over nonplastic genotypes. In 

addition, the metapopulation structure 

mediated by coaster brook trout 

(D’Amelio and Wilson 2008, p. 1222; 

Ridgway 2008, p. 1181) favors plasticity 

over adaptive genetic differences among 

populations because dispersal among 

populations increases environmental 

heterogeneity and favors an increase in 

trait reaction norm (the pattern of 

visible characteristics produced by a 

given genetic makeup of an organism 

under different environmental 

conditions; Sultan and Spencer 2002, p. 

281). Alternatively, the adfluvial and 

lacustrine ecotypes on Isle Royale are 

physically isolated and in this situation, 

adaptive radiation would be favored 

over the evolution of phenotypic 

plasticity (Price 2003, pp. 1437–1438). 

If phenotypic plasticity is the source 

of differences observed between streamresident and brook trout, then these 

ecotypes are expressed in a single 

population and represent the extremes 

of the reaction norm for migratory 

behavior. Scribner et al. (2008, p. 10) 

did not observe genetic differences 

between sympatric adfluvial brook trout 

and presumed stream-resident ecotypes 

in the Salmon Trout River on the south 

shore of Lake Superior. Analysis of 

microsatellite DNA provided high 

statistical power to detect genetic 

differences between ecotypes. In fact, 

the authors did observe highly 

significant genetic differences between 

brook trout sampled above and below 

the impassable waterfall in this system. 

In addition, when collections from the 

Salmon Trout River were compared 

with native brook trout populations 

sampled from 10 other nearby 

tributaries, the lowest pairwise measure 

of genetic distinction was observed 

between the resident and adfluvial 

ecotypes sampled below the waterfall in 

the Salmon Trout River. D’Amelio and 

Wilson (2008, p. 1221) used similar 

methods to document that adfluvial 

brook trout in the Nipigon Bay were not 

genetically distinct from presumed 

resident brook trout sampled from 

tributaries to the bay. These findings in 

the Salmon Trout River and the Nipigon 

Bay area indicate phenotypic plasticity 

likely plays a major role in the 

expression of the adfluvial and fluvial 

ecotypes. 

Theriault et al. (2008, pp. 417–419) 

used an eco-genetic model to 

demonstrate that intensive harvest of 

anadromous fish reduces the probability 

of migration in brook trout over the 

course of 100 years. This study provides 

a basic framework for understanding 

how fisheries-induced selection 

(mortality from fishing) influences the 

evolution of alternate life-history tactics 

that are expressed by phenotypic 

plasticity. For example, directional 

selection imposed by fishing-induced 

mortality on coaster brook trout confers 

high fitness to the survivors of the 

fishery but not necessarily with respect 

to natural selection. There is also 

uncertainty regarding the rate of 

recovery for expression of the adfluvial 

form after fishing selection is reduced or 

eliminated because there is not 

automatically equal directional 

selection in the opposite direction for 

expression of the adfluvial form. In the 

case of the coaster, habitat degradation 

and competition from nonnative salmon 

may exclude brook trout from habitats 

that would allow juvenile brook trout to 

achieve growth rates necessary to 

express the adfluvial coaster ecotype 

(Huckins et al. 2008, pp. 1337–1339). 

Additionally, metapopulation structure 

mediated by coaster brook trout 

(D’Amelio et al. 2008, p. 1348) favors 

plasticity over adaptive genetic 

differences among populations (Sultan 

and Spencer 2002, p. 281). Loss of 

coasters in most populations in Lake 

Superior has reduced migration among 

populations (Sloss et al. 2008, p. 1249) 

resulting in a reduction in 

environmental heterogeneity favoring a 

decrease in the reaction norm of traits. 

These studies demonstrate that humaninduced selective forces can alter the 

reaction norm for a population which 

can result in the loss of plasticity 

needed to express the coaster lifehistory forms. 

Brook trout experts contend that if 

environmental conditions are suitable 

(i.e., threats are abated), the adfluvial 

life form of brook trout populations in 

Lake Superior can be readily 

reconstituted from purely resident stock 

(USFWS 2009, p. 8); this is believed 

unlikely for other salmonids (e.g., 

Oncorhynchus mykiss). This assertion is 

predicated on three premises. First, 

adult brook trout of one ecotype may 

produce offspring of the other ecotype. 

For example, two resident fish could 

breed and produce offspring that exhibit 

both the adfluvial and fluvial lifehistory strategies. Further, streamresident and adfluvial ecotypes from the 

same population interbreed. This means 

that within a stream, individuals that 

exhibit the resident and adfluvial forms 

reside within and are drawn from the 

same population. Second, the chars 

(genus Salvelinus), including brook 

trout, show greater phenotypic plasticity 

than most other salmonids. Adfluvial 

brook trout do not require substantial 

physiological changes (for example, 

smoltification) to successfully migrate 

and survive in the lake environment. 

Thus, the fitness costs to maintain the 

genetic code for plasticity are likely less 

relative to saltwater-dwelling 

salmonids. Hence, it is reasonable to 

expect a brook trout population will 

maintain the ability (genetic code) to 

express the full array of life forms over 

time. Third, life-history strategy for 


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brook trout is strongly controlled by 

environmental conditions or triggers. As 

such, the experts believe that, provided 

the necessary environmental conditions 

or triggers exist, life forms can be 

expressed even if temporally lost from 

a population. 

Current Population Status of Brook 

Trout 

The current range of native brook 

trout remains generally unchanged, 

extending through much of eastern 

North America, from eastern Canada, 

south through the Great Lakes and 

northeast to Georgia in the U.S. 

However, populations throughout this 

range have experienced significant 

declines. The current range of native 

brook trout started diminishing over the 

past 200 years as a result of ecosystem 

disruption following European 

settlement of North America (Newman 

and DuBois 1997). Habitat destruction 

by forestry, agricultural practices, 

industrial water use, dams, and 

pollution were responsible for this 

decline (Power 1980, p. 141). Brook 

trout were once present in nearly every 

coldwater stream and river in the 

eastern U.S. and Canada, but 

populations began to disappear as early 

agriculture, timber, and textile practices 

and industries cleared the region’s 

protective forests and degraded the 

streams with sediment and pollution 

(Power 1980, p. 141; EBJV 2006, p. 1). 

Throughout much of their natural 

range, remaining stream populations 

have retreated into extreme headwater, 

high elevation, or upstream reaches 

(EBJV 2006, p. 2). In the eastern U.S., 

healthy stream populations of brook 

trout (wild brook trout occupying 90– 

100 percent of their historical habitat) 

exist in only 5 percent of subwatersheds 

(EBJV 2006, p. 2). Anadromous stocks 

along the U.S. coast and in many 

Canadian rivers have been decimated by 

dams and estuarine pollution (Power 

1980, p. 195). In the southern portion of 

its range (southern Appalachian 

Mountains), brook trout populations 

have declined by 75 percent, persisting 

now only in isolated headwater reaches 

(EBJV 2006, p. 6). 

Various threats are persistent across 

the brook trout range. Most of them 

involve habitat loss and degradation, 

such as poor land management, high 

water temperature, sedimentation 

(roads), urbanization, degraded riparian 

habitat, stream fragmentation (roads), 

dam inundation/fragmentation, and 

forestry practices (EBJV 2006, pp. 3, 5). 

Poor land management associated with 

agriculture (such as clearing streamside 

vegetation, over-grazing sensitive areas, 

ineffectively managing nutrients, and 

ditching small streams) ranks as the 

most widely distributed impact to brook 

trout across the eastern U.S. (EBJV 2006, 

p. 2). Climate change presents a 

significant threat to brook trout, with 

some southern portions predicted to 

lose between 53–97 percent of their 

brook trout habitat due to high water 

temperatures (Flebbe 2006, p. 1379). 

While some uncertainty remains about 

the exact temperature increase that will 

result from climate change, the present 

range of brook trout is predicted to 

shrink, particularly in the southern 

Appalachians (Hudy et al. 2005, p. 5). 

Nonnative species are now present 

throughout most of the range (Parsons 

1973, p. 5). Interactions with these 

nonnatives are considered to be among 

the most significant biological threats to 

brook trout rangewide (Peck 2001, p.13; 

Hudy et al. 2005, p. 3; EBJV 2006, pp. 

2–3, 5). Brown trout have been shown 

to displace or reduce stream 

populations of brook trout throughout 

their natural range (Nyman 1970, p. 348; 

Fausch and White 1981, p. 1226; Waters 

1983, p. 144). Encroachment by rainbow 

trout has also been documented in the 

contraction of the range of native brook 

trout across their native range (Kelly et 

al., 1980, pp. 9–10; Power 1980, p. 195; 

Larson and Moore 1985, p. 200). Species 

such as small mouth bass and yellow 

perch are considered to be significant 

competitors with lake-dwelling brook 

trout (EBJV 2006, pp. 22, 28, 34). 

Current Population Status of Brook 

Trout in the Upper Great Lakes 

Brook trout populations throughout 

the upper Great Lakes region are 

relatively common and geographically 

widespread, although distribution and 

abundance is much reduced from 

historical levels (Power 1980, p. 195; 

Becker 1983, pp. 321–322; WIDNR and 

USFWS 2005, p. 17). Dramatic declines 

in abundance and distribution of both 

coaster and stream-resident ecotypes of 

brook trout occurred in the upper Great 

Lakes from the 1850s to mid-1900s 

(Goodier 1982, pp. 110, 112; Ritchie and 

Black 1988, p. 15; Newman and Dubois 

1997, pp. 4–6; Enterline 2000, p. 1; 

WIDNR and USFWS 2005, pp. 17–18; 

Schreiner et al. 2008, p. 1305; Schreiner 

et al. 2008, p. 1351; Huckins et al. 2008, 

p. 1322). 

There are presently at least 200 

streams with documented brook trout 

populations in the upper Great Lakes 

(Moore and Bream 1965, p. 19; Goodier 

1982, p. 110; Enterline 2000, p. 30; 

Newman et al. 2003, pp. 31–37; Quinlan 

2004, unpub. data; Bassett 2009, unpub. 

data; Ward 2007, p. 16; Schram 2008b, 

pers. comm.; Scott 2008, pers. comm.; 

Chase 2009, pers. comm.; OMNR 2009, 

unpub. data). The current specific status 

of most of these populations is not 

known, but they are described by the 

Michigan, Minnesota, and Wisconsin 

natural resource agencies as stable and 

self-sustaining in the upper Great Lakes 

(Holtz 2008, p. 2; MIDNR 2008a, p. 49; 

Schreiner and Ebbers 2008, pers. 

comm.). 

In coldwater tributaries to the upper 

Great Lakes, brook trout were 

historically distributed from the river 

mouth upstream to the headwaters or to 

impassible barriers (Smith and Moyle 

1944, p. 119; Moore and Braem 1965, p. 

19; Goodier 1982, p. 111; Becker 1983, 

p. 321; WIDNR and USFWS 2005). The 

brook trout numbers in these stream 

reaches once numbered in the hundreds 

to thousands (Huckins and Baker 2008, 

p. 1231). A 30-year data set from 

Wisconsin tributaries shows that, in 

streams historically occupied solely by 

brook trout, brook trout have contracted 

into upstream sections and are now 

nearly absent in lower reaches (WIDNR 

2008, unpub. data). Brook trout 

abundance has declined despite the 

persistence of suitable conditions for 

brook trout and high numbers of 

juvenile nonnative salmonids (WIDNR 

2008, unpub. data). In Wisconsin 

tributaries to Lake Superior, the 

distribution of stream-resident brook 

trout populations has declined by nearly 

50 percent from historical levels 

(WIDNR and USFWS 2005, p. 17). 

Historically, 119 tributaries to Lake 

Superior and purportedly 6 Lake Huron 

streams supported populations of brook 

trout with coaster ecotypes (Newman et 

al. 2003, pp. 31–38; Enterline 2000, p. 

30). Once abundant and widespread 

throughout the northern portions of the 

Great Lakes, populations of brook trout 

that still exhibit the coaster ecotypes are 

presently limited to a few locations 

(Dehring and Krueger 1985, p. 1; Bailey 

and Smith 1981, p. 1549; Goodyear et al. 

1982, pp. 63–65; Enterline 2000, p. 30; 

Newman et al. 2003, p. 39; Schreiner et 

al. 2008, p. 1351; Mucha and Mackereth 

2008, p. 1). Although self-sustaining 

populations of stream-resident brook 

trout are currently present in 56 of 58 

U.S. streams and in all 61 Canadian 

streams identified in the Brook Trout 

Rehabilitation Plan for Lake Superior as 

historically supporting populations with 

coaster ecotypes (Newman et al. 2003, 

pp. 31–37; Quinlan 2008, unpub. data; 

Schreiner 2008, pers. comm.; Schram 

2008c, pers. comm.; Scott 2008, pers. 

comm.; Chase 2009, pers. comm.), only 

18 populations with coaster ecotypes 

still persist there (15 stream-spawning– 

adfluvial, and 3 lake-spawning– 

lacustrine) (Goodyear 1982, pp. 63–65; 

Quinlan 1999, p. 19; Ritchie and Black 


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1988, p. 15; Swainson 2001, p. 41; 

Newman et al. 2003, pp. 28–39; 

Enterline 2000, p. 30; Chase 2009, pers. 

comm.). 

Over the last decade, the presence of 

coaster brook trout has been confirmed 

in other locations within the upper 

Great Lakes. Surveys, and in some cases 

genetic analysis, have confirmed the 

presence of brook trout with coaster 

ecotypes in the following locations; 

Minnesota tributaries to Lake Superior 

(Newman et al. 1999, p. 2; BurnhamCurtis 2000, p. 4; Pranckus and 

Ostazeski 2003, p. 5; Ward 2007, p. 16), 

three Michigan tributaries to Lake 

Superior (Stimmel 2006, p. 56; MIDNR 

2008a, p. 2; Leonard 2009, pers. comm.), 

along the shoreline of the Red Cliff 

Indian Reservation, Wisconsin (Stott 

and Quinlan 2008, p. 21), and in Little 

Todd Harbor and Rock Harbor, Isle 

Royale (Gorman et al. 2008, p. 1257). 

The origin of these fish is unknown and 

natural reproduction of fish exhibiting 

the coaster ecotype has not been 

confirmed, therefore these locations are 

not identified as supporting selfsustaining populations. However, they 

have potential to be self-sustaining 

populations, as outlined by Schreiner et 

al. (2008). 

Abundance of individuals in 

populations exhibiting the coaster 

ecotypes is stable or increasing in 

several regions of Lake Superior. In the 

Salmon Trout River, Michigan, 

abundance as determined by video 

surveillance increased from 118 to 243 

in the period from 2004 to 2006 (MIDNR 

2008a, p. 6). In the Nipigon River, angler 

catch per hour has increased from the 

late 1980s to the present, while harvest 

has decreased substantially (Houle 

2004, p. 13). In South Bay, Lake 

Nipigon, estimates of spawner 

abundance continue to increase and 

currently number about 600 fish—up 

from fewer than 100 in the recent past, 

but still fewer than the estimated 2,500 

present in the mid-1900s (Swainson 

2009, pers. comm.). In Tobin Harbor, 

Isle Royale National Park, Michigan, 

estimates of adult brook trout from 

1996, 2001, and 2008 has remained 

around 200–250 fish (USFWS 

unpublished data). Relative abundance 

based on shoreline electrofishing index 

surveys in Tobin Harbor from 1997 to 

2008 has fluctuated from 0.3 per hour to 

16.7 per hour (USFWS 2008, unpub. 

data). 

There are reintroduction stocking 

efforts ongoing in several streams on the 

Grand Portage Indian Reservation 

(Newman and Johnson 1996, p. 4), Red 

Cliff Indian Reservation, Keweenaw Bay 

Indian Community Reservation 

(Donofrio 2002, p. 1), and in Whittlesey 

Creek, Wisconsin (USFWS and WIDNR 

2003, p. 5). Supplementation stocking 

occurred in Siskiwit Bay, Isle Royale, 

from 1999 to 2005. Data collected to 

date indicates limited success with 

these efforts (Newman et al. 1999, p. 2; 

Quinlan 2008, pers. comm.; Stott and 

Quinlan 2008, p. 22). Reintroduction 

efforts in Michigan have recently been 

terminated in the Gratiot, Little Carp, 

Hurricane, and Mosquito Rivers and 

Sevenmile Creek (Scott 2007, pers. 

comm.; Loope 2007, pers. comm.). 

Threats to brook trout across its native 

range are also acting on brook trout 

within the upper Great Lakes. A primary 

impact is the presence of introduced 

fishes (e.g., non-native salmonids). 

Introduced salmonids have competitive 

and predatory impacts on brook trout, 

although the precise mechanisms may 

not be fully understood and the 

magnitude of impact may vary by 

species, population size, and 

environmental conditions. The decline 

or loss of the migratory coaster form has 

diminished connectivity among 

populations that once operated as 

metapopulations. Populations that occur 

in such isolated patches can be lost, 

increasing the possibility of extirpation. 

As a species, brook trout are known to 

be highly susceptible to exploitation by 

anglers (Newman and Dubois 1996, p. 3; 

Newman et al. 2003, p. 11; Huckins et 

al. 2008, p. 1322). Overharvest was a 

primary cause of the decline of Great 

Lakes brook trout populations by the 

early 1900s, especially the coaster 

ecotype, and continues to threaten some 

populations within the region (Newman 

and Dubois 1996, p. 1; Huckins et al. 

2008, p. 1322; Schreiner et al. 2008, p. 

1356). Climate change also presents a 

threat to upper Great Lakes brook trout, 

through increased water temperatures, 

leading to increased presence of 

nonnative competitors and predators 

along with a decrease in habitat 

suitability. Although the enormous 

coldwater reservoir within the lake 

environment represents a potential 

refuge for Great Lakes brook trout, 

predicted impacts in both stream and 

lake environments still represent a 

potential threat to their long-term 

viability. 

Defining a Species Under the Act 

Section 3(16) of the Act defines 

‘‘species’’ to include ‘‘any species or 

subspecies of fish and wildlife or plants, 

and any distinct vertebrate population 

segment of fish or wildlife that 

interbreeds when mature’’ (16 U.S.C. 

1532 (16)). Our implementing 

regulations at 50 CFR 424.02 provide 

further guidance for determining 

whether a particular taxon or 

population is a species or subspecies for 

the purposes of the Act: ‘‘The Secretary 

shall rely on standard taxonomic 

distinctions and the biological expertise 

of the Department and the scientific 

community concerning the relevant 

taxonomic group’’ (50 CFR 424.11). As 

previously discussed, coaster brook 

trout are classified as Salvelinus 

fontinalis, the same as other brook trout, 

and as such we do not consider the 

coaster form of the brook trout to 

constitute a distinct species or 

subspecies. Since the coaster brook trout 

is not a distinct species or subspecies, 

we then evaluated whether the coaster 

brook trout is a distinct vertebrate 

population segment to determine 

whether it would constitute a listable 

entity under the Act. 

To interpret and implement the 

distinct vertebrate population segment 

(DPS) provisions of the Act and 

Congressional guidance, the Service and 

the National Marine Fisheries Service 

(now the National Oceanic and 

Atmospheric Administration— 

Fisheries), published the Policy 

Regarding the Recognition of Distinct 

Vertebrate Population Segments (DPS 

Policy) in the Federal Register on 

February 7, 1996 (61 FR 4722). Under 

the DPS Policy, three elements are 

considered in the decision regarding the 

establishment and classification of a 

population of a vertebrate species as a 

possible DPS. These are applied 

similarly for additions to and removals 

from the List of Endangered and 

Threatened Wildlife and Plants. These 

elements are (1) the discreteness of a 

population in relation to the remainder 

of the species to which it belongs, (2) 

the significance of the population 

segment to the species to which it 

belongs, and (3) the population 

segment’s conservation status in relation 

to the Act’s standards for listing, 

delisting, or reclassification. 

Distinct Vertebrate Population Segment 

Analysis 

In accordance with our DPS Policy, 

this section details our analysis of the 

first two elements used to assess 

whether a vertebrate population 

segment under consideration for listing 

may qualify as a DPS. These elements 

are (1) the population segment’s 

discreteness from the remainder of the 

species to which it belongs and (2) the 

significance of the population segment 

to the species to which it belongs. 

Discreteness refers to the ability to 

circumscribe a population segment from 

other members of the taxon based on 

either (1) physical, physiological, 

ecological, or behavioral factors or (2) 

international boundaries that result in 


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significant differences in control of 

exploitation, habitat management, 

conservation status, or regulatory 

mechanisms in light of section 4(a)(1)(B) 

of the Act. 

Under our DPS Policy, if we have 

determined that a vertebrate population 

segment is discrete, we consider its 

biological and ecological significance to 

the larger taxon to which it belongs in 

light of Congressional guidance (see 

Senate Report 151, 96th Congress, 1st 

Session) that the authority to list DPSs 

be used ‘‘sparingly’’ while encouraging 

the conservation of genetic diversity. To 

evaluate whether a discrete vertebrate 

population may be significant to the 

taxon to which it belongs, we consider 

the best available scientific evidence. 

This evaluation may include, but is not 

limited to: (1) Evidence of the 

persistence of the discrete population 

segment in an ecological setting that is 

unusual or unique for the taxon; (2) 

evidence that loss of the population 

segment would result in a significant 

gap in the range of the taxon; (3) 

evidence that the population segment 

represents the only surviving natural 

occurrence of a taxon that may be more 

abundant elsewhere as an introduced 

population outside its historical range; 

and (4) evidence that the discrete 

population segment differs markedly in 

its genetic characteristics from other 

populations of the species. 

The first step in our DPS analysis was 

to identify population segments of the 

brook trout to evaluate. The petition 

asked us to (1) ‘‘list as ‘endangered’ the 

naturally spawning anadromous (lakerun) Coaster Brook Trout (Salvelinus 

fontinalis) throughout its known 

historic range in the conterminous 

United States’’ (including designation of 

critical habitat) and (2) ‘‘determine 

whether the Salmon Trout River (STR) 

coaster is a DPS’’ and (3) ‘‘whether the 

south shore of Lake Superior population 

of coasters (which are known to breed 

today only in the STR) is ‘endangered.’ ’’ 

Although brook trout in the Great Lakes 

exhibit three life-history forms (fluvial, 

adfluvial, and lacustrine), the petition 

specifically focused on the coaster, or 

adfluvial and lacustrine, forms. 

To address the entity identified in the 

first petition request (coaster brook trout 

throughout their historical range in the 

U.S.), we identified two approaches to 

analyzing a potential population 

segment: (1) Describe and analyze an 

upper Great Lakes ‘‘all brook trout’’ 

population segment, which includes all 

brook trout life forms—fluvial, 

adfluvial, and lacustrine ecotypes, 

inclusive of coaster brook trout—present 

throughout the documented historical 

range of brook trout in the Great Lakes 

basin, and (2) describe and analyze an 

upper Great Lakes ‘‘coaster-only’’ 

population segment, which includes 

only the coaster forms—adfluvial and 

lacustrine ecotypes—of brook trout 

throughout the documented historical 

range of brook trout in the Great Lakes 

basin. 

We find that neither of the population 

segments analyzed constitute a valid 

DPS, and therefore the first petitioned 

entity, coaster brook trout throughout 

their historical range in the U.S., is not 

a valid DPS. To address the second and 

third petition requests, we focused on 

the brook trout population in the 

Salmon Trout River and evaluated 

whether it qualified as a DPS per our 

policy. We find that the brook trout 

population in the Salmon Trout River 

also does not constitute a valid DPS. 

The remainder of this section details the 

evaluation of these population segments 

as DPSs per our 1996 DPS Policy. 

Upper Great Lakes All Brook Trout 

Population Segment 

This population segment 

encompasses the range of brook trout 

populations within the Great Lakes 

basin that currently or historically 

occupied both the tributary and lake 

environments (including streamresident, adfluvial, and lacustrine 

ecotypes of brook trout). Although 

technically not one of the ‘‘Great 

Lakes,’’ we include Lake Nipigon in 

Canada in this population because it is 

part of the Great Lakes drainage. The 

best available information indicates the 

known historical range of brook trout 

within the basin included all of Lake 

Superior and its drainage (including 

Lake Nipigon), and the northern 

portions of Lakes Michigan and 

Huron—specifically, that portion of 

Lake Michigan north of a line from the 

Sheboygan River, Wisconsin to Grand 

Traverse Bay, Michigan, and that 

portion of Lake Huron north of Thunder 

Bay, Michigan, eastward to include 

Manitoulin Island to the 81°30′ 

longitudinal demarcation and west of 

81°30′ longitude (MacCrimmon and 

Campbell 1969, p. 1701; Dehring and 

Krueger 1985, p. 1; Enterline 2000, pp. 

29–30). 

Discreteness 

Marked Separation 

As previously described, the Upper 

Great Lakes brook trout population 

segment we have evaluated 

encompasses the range of brook trout 

populations that currently or 

historically occupied both the tributary 

and lake environments within the Great 

Lakes basin. Brook trout within this 

population segment are physically 

isolated from other populations of brook 

trout as the result of the physical 

separation between the drainage of the 

Great Lakes basin and neighboring 

drainages. Consequently, brook trout in 

the Great Lakes basin meet the 

discreteness criterion of being markedly 

separate from other members of the 

brook trout taxon. 

International Border 

We presently do not find that the 

brook trout in the Upper Great lakes on 

either side of the international United 

States border with Canada are discrete 

due to differences in control of 

exploitation, management of habitat, 

conservation status, or regulatory 

mechanisms that are significant in light 

of section 4(a)(1)(D) of the Act. 

Conclusion for Discreteness 

In conclusion, we determine that the 

Upper Great Lakes brook trout 

population segment, as defined here, is 

discrete from the remainder of the brook 

trout taxon. This discreteness arises 

from the population segment’s physical 

isolation from the remainder of the 

taxon. Therefore, we will now consider 

the potential significance of this discrete 

population segment to the remainder of 

the taxon. 

Significance 

We have determined that the 

population of brook trout in the Upper 

Great Lakes meets the discreteness 

elements of the DPS policy, and as such, 

we will now evaluate whether this 

specific population is significant to the 

taxon as a whole (i.e., native brook trout 

in eastern North America). A discrete 

population is considered significant 

under the DPS policy if it meets one of 

four of the elements identified in the 

policy under significance or can 

otherwise be reasonably justified as 

being significant. 

We discuss further below our 

evaluation of the significance of the 

population of brook trout in the Upper 

Great Lakes relative to the taxon as a 

whole. 

Evidence of the Persistence of the 

Discrete Population Segment in an 

Ecological Setting That Is Unusual or 

Unique for the Taxon 

On the basis of an evaluation of the 

best available scientific information, we 

have determined that the habitat for 

brook trout in the Upper Great Lakes 

does not represent an ecological setting 

that is unusual or unique for the native 

brook trout relative to the habitat 

available to it throughout the entire 


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taxon’s range in eastern North America. 

A summary of our evaluation is below. 

Brook trout exhibiting differing lifehistory forms occupy a variety of 

ecosystems from subarctic regions of the 

Hudson Bay coast, to temperate areas 

bordering and east of the Great Lakes, 

and southern coldwater habitats in the 

Appalachian Mountains of Tennessee 

and Georgia (Power 1980, p. 142). They 

have been successfully naturalized in 

western North America, South America, 

Eurasia, Africa, and New Zealand 

(MacCrimmon and Campbell 1969, p. 

1699, pp. 1703–1717). Within their large 

native range in eastern North America, 

brook trout habitat includes coastal 

areas and various-sized lakes, streams, 

and rivers at varying altitudes. Most 

populations inhabit coldwater streams, 

but lake-dwelling and lake-spawning 

(lacustrine form) populations also occur 

throughout the range, in spring-fed 

ponds, small- to medium-sized lakes, 

and a few large, oligotrophic (containing 

relatively little plant life or nutrients, 

but rich in dissolved oxygen) lakes. 

Anadromous populations (‘‘salters’’) of 

brook trout use marine habitats in 

Hudson Bay and along the Atlantic 

coast. 

The upper Great Lakes represent a 

complex ecological setting for brook 

trout. The very large size of the Great 

Lakes watershed creates an environment 

that more closely resembles oceanic 

physical conditions (available to the 

anadromous forms of brook trout) than 

conditions in smaller lakes (available to 

other forms of brook trout). With 

approximately 1,500 tributaries and 

almost 2,800 miles (4,506 km) of 

shoreline, Lake Superior also provides 

brook trout access to a very large 

freshwater habitat network. Although 

the Great Lakes are the largest 

freshwater water bodies occupied by 

brook trout, there are thousands of lakes 

in its range including large postglacial 

lakes further north in Canada that 

contain populations of the adfluvial and 

lacustrine forms (e.g., Fraser and 

Bernatchez 2008, p. 1193). 

If predicted rising water temperatures 

in response to climate change are 

realized over the entire range of brook 

trout, the distributions of brook trout 

populations would probably shift 

toward cooler waters at higher latitudes 

and altitudes (Meisner 1990b, p. 1068; 

Magnuson et al. 1997, p. 859; Kling et 

al. 2003, pp. 53–54). The greatest effects 

would likely begin in populations 

located at the margins of the taxon’s 

hydrologic and geographic distributions 

(Meisner et al. 1990a, p. 282, Kling et al. 

2003, p. 54). Although the upper Great 

Lakes have already experienced some 

impacts of climate change (see Kling et 

al. 2003, pp. 14–16) and will not be 

immune to future impacts (see Kling et 

al. 2003, pp. 21–25), they may provide 

substantial coldwater habitat for brook 

trout in the future. However, brook trout 

have abundant coldwater habitat 

available in the northern latitudes of its 

range, and habitat in northern North 

America which is presently too cold 

may develop into appropriate brook 

trout habitat under a warming scenario. 

We will further evaluate the extent that 

this may be the case in the range-wide 

assessment of native brook trout that we 

plan to conduct (see Finding section). 

Although the upper Great Lakes 

represent a diverse and complex 

ecological setting which may offer 

potential coldwater habitat for brook 

trout, we must evaluate the breadth of 

ecological diversity of brook trout 

habitat rangewide in our assessment of 

this population segment’s significance 

to the rest of the taxon. First, available 

information indicates that the large area 

and wide geographical range of brook 

trout habitats, which vary in latitude 

and altitude and water form, contain a 

vast diversity of habitats for brook trout. 

The ecological setting of the upper Great 

Lakes is a small portion of the brook 

trout range, and based on available 

information, its relative significance to 

the brook trout species is limited. 

Second, although we expect that the 

Great Lakes may offer substantial 

coldwater habitat, there are other large, 

deep, oligotrophic lakes, and numerous 

lakes and streams at higher latitudes 

that may buffer the species from 

potential climate change impacts. Given 

the available information on the 

diversity and extent of ecological 

settings of brook trout in the rest of its 

range, we conclude at this time that the 

upper Great Lakes is a not unique or 

unusual setting of significance for the 

native brook trout in eastern North 

America. 

Evidence That Loss of the Population 

Segment Would Result in a Significant 

Gap in the Range of the Taxon 

Loss of brook trout, including any or 

all life forms, in the upper Great Lakes, 

when considered in relation to brook 

trout throughout the remainder of the 

species’ range in eastern North America, 

would mean the loss of a small 

geographic portion (approximately ten 

percent) of the entire range of the taxon. 

Further, the number of streams with 

populations in the upper Great Lakes 

(about 200) are a small proportion of the 

amount of streams and lakes with brook 

trout populations in the rest of the 

native range in eastern North America. 

Due to the broad geographic range of 

brook trout, the wide diversity of 

habitats available to it, and its plasticity, 

and the fact that the upper Great Lakes 

are at the western periphery of its 

natural range, we find that the gap in 

the range resulting from the loss of 

brook trout in the upper Great Lakes 

would not be significant. 

Evidence That the Population Segment 

Represents the Only Surviving Natural 

Occurrence of a Taxon That May Be 

More Abundant Elsewhere as an 

Introduced Population Outside Its 

Historical Range 

This criterion from the DPS policy 

does not apply to the brook trout in the 

upper Great Lakes because it is not a 

population segment representing the 

only surviving natural occurrence of the 

taxon that may be more abundant 

elsewhere as an introduced population 

outside its historical range. 

Consequently, this population of brook 

trout does not meet the significance 

element of this factor. 

Evidence That the Discrete Population 

Segment Differs Markedly in Its Genetic 

Characteristics From Other Populations 

of the Species 

A large amount of rangewide genetic 

variation for brook trout is distributed 

among brook trout populations (large 

Fst values, values in a fixation index 

which describe the degree of population 

differentiation based on genetic 

polymorphisms). This pattern is heavily 

influenced by the ecological and lifehistory characteristics of brook trout 

populations (population connectivity or 

isolation, philopatric tendency). 

We find that, based on the genetic 

information currently available 

(outlined under the Brook Trout 

Genetics section above), the brook trout 

in the upper Great Lakes, including all 

life forms, do not differ markedly from 

other populations of the species in their 

genetic characteristics (such as 

exhibiting unique alleles or a proportion 

of genetic variability beyond the norm 

of distribution) such that they should be 

considered biologically or ecologically 

significant based simply on genetic 

characteristics. They do not show any 

more genetic distinctiveness in 

comparison to the remainder of the 

taxon than other populations 

demonstrate. With the additional 

consideration that the authority to list 

DPSs be used ‘‘sparingly,’’ we conclude 

that this population segment of brook 

trout does not meet the significance 

element of this factor. 

DPS Conclusion—Upper Great Lakes All 

Brook Trout Population Segment 

On the basis of the best available 

information, we conclude that the allVerDate Nov<24>2008 15:22 May 18, 2009 Jkt 217001 PO 00000 Frm 00026 Fmt 4702 Sfmt 4702 E:\FR\FM\19MYP1.SGM 19MYP1

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brook-trout population segment in the 

Upper Great Lakes is discrete due to 

marked separation as a consequence of 

physical, ecological, physiological, or 

behavioral factors according to the 1996 

DPS Policy. However, on the basis of an 

evaluation of brook trout in the Great 

Lakes relative to the four significance 

elements of the 1996 DPS Policy, we 

conclude that this discrete population 

segment is not significant to the taxon 

to which it belongs, and therefore, does 

not qualify as a DPS under 1996 policy. 

As such, we find that population of 

brook trout in the Great Lakes basin is 

not a listable entity under the Act. 

Upper Great Lakes Coaster-Only Brook 

Trout Population Segment 

This population segment 

encompasses the historical range of 

brook trout populations in the Great 

Lakes basin exhibiting the coaster 

ecotypes, which includes northern 

portions of the Lakes Michigan and 

Huron and all of Lake Superior, 

including Lake Nipigon (see 

Discreteness analysis for the Upper 

Great Lakes All Brook Trout Population 

Segment below for more detailed range 

description). 

Discreteness 

Hubbs and Lagler (1949, p. 44) and 

Becker (1983, p. 320) described coasters 

as brook trout that spend a portion of 

their life cycle in the Great Lakes. 

Coaster brook trout have long been 

recognized by local and scientific 

communities (Newman and Dubois 

1997, p. 4). 

Marked Separation 

As described previously, coasters are 

adfluvial and lacustrine life forms of 

brook trout that occupy the nearshore 

zone of the Great Lakes. Coasters, being 

a subset of brook trout within the Great 

Lakes basin, are markedly separate from 

all other brook trout outside of the Great 

Lakes Basin as the result of the physical 

separation between the drainage of the 

Great Lakes basin and neighboring 

drainages. Thus, brook trout within this 

population segment are markedly 

separate from other members of the 

brook trout taxon outside the Great 

Lakes basin because they are physically 

isolated. 

Isolation also exists within the Great 

Lakes basin, among brook trout 

populations in Lakes Huron, Michigan, 

Erie, and Ontario. The best available 

information indicates that adfluvial 

brook trout likely did not historically 

occupy lake waters of southern Lakes 

Michigan and Huron (boundary as 

previously defined in this section) or 

Lakes Erie and Ontario (MacCrimmon 

and Campbell 1969, p. 1700; Bailey and 

Smith 1981, p. 1549; Dehring and 

Krueger 1985, p. 1; MIDNR 2008a, pp. 

2–3). Brook trout found within these 

lake areas in the last 100 years are likely 

the result of stocking as no known 

adfluvial, migratory or lake dwelling 

populations exist. The reason that brook 

trout never occupied these lake areas is 

unknown; we suspect that unidentified 

environmental conditions preclude 

brook trout use of these habitats. 

Regardless, without brook trout use of 

the lake environment, natural dispersal 

between stream populations cannot 

occur. This absence of adfluvial and 

lacustrine ecotypes in these populations 

effectively restricts populations with 

coaster brook trout forms to the 

distribution previously defined, namely 

the watershed and lake habitats of all of 

Lake Superior, and the northern 

portions of Lakes Michigan and Huron. 

Within the Great Lakes basin, coasters 

are ecologically, behaviorally, and 

physiologically discrete from streamresident brook trout. Coasters are 

markedly separate from resident brook 

trout in their lake-dwelling and 

adfluvial behavior (Hubbs and Lagler 

1949, p. 44; Becker 1983, p. 320; 

Huckins and Baker 2008, p. 1229; 

Schreiner et al. 2008, p. 1350). Lakedwelling coasters spend their entire life 

within the lake environment (Huckins et 

al. 2008, p. 1323; Schreiner et al. 2008, 

p. 1350); adfluvial coasters move 

between streams and the lake (Huckins 

et al. 2008, p. 1323). Stream-resident 

brook trout remain within the river 

system. These differences mark an 

ecological (i.e., lake versus stream 

habitat) and a behavioral (i.e., 

migratory) separation between the two 

forms. 

Coaster ecotypes and stream-resident 

ecotypes of brook trout also differ 

physiologically in adult size, longevity, 

age at maturity, and fecundity. As stated 

in the Species Description section 

above, adult coasters range in size from 

12 to 25 in (30 to 64 cm), and commonly 

reach lengths of 16 in (41 cm) (Ritchie 

and Black 1988, pp. 50–51; Quinlan 

1999, p. 17; Huckins and Baker 2008, p. 

1239; Huckins et al. 2008, p. 1337). The 

body mass of adult coasters typically 

ranges from 0.75 to 8 pounds (341 to 

3632 g) (Quinlan 1999, p. 16; Swainson 

2001, p. 60; Huckins and Baker 2008, p. 

1239; WIDNR and USFWS 2005, p. 16) 

with a maximum measurement of 14.5 

pounds (6577 g) (Scott and Crossman 

1973, p. 211). Adult resident brook trout 

typically range in size from 5 to 15 in 

(13 to 38 cm) (Scott and Crossman 1979, 

p. 208; Becker 1983, pp. 318, 320; 

WIDNR and USFWS 2005, p. 16; 

Schram 2008a pers. comm.) and usually 

weigh less than a pound (<454 g) 

(WIDNR and USFWS 2005, p. 16). Most 

female coasters do not reach maturity 

until they are 2 to 4 years old and 12 

to 15 in. (30 to 38 cm) in length (Ritchie 

and Black 1998, p. 19; Quinlan 1999, p. 

11; Huckins and Baker 2008, p. 1241; 

Huckins et al. 2008, p. 1329), and live 

5 to 8 years (Quinlan 1999, p. 11; 

Huckins et al. 2008, p. 1328). Whereas 

most female stream-resident brook trout 

mature by age 1 or 2 (Becker 1983, p. 

318), and typically live to age 3 and 

rarely reach ages of 4 or 5 years (Scott 

and Crossman 1973, p. 211, Becker 

1983, p. 318). Coaster females produce 

around 1,500 to 3,000 eggs (Quinlan 

1999, p. 20; Swainson 2001, p. 41), 

while stream-resident brook trout 

fecundity ranges from 100 to 1,500 eggs 

per female (Scott and Crossman 1973, p. 

210; Power 1980, p. 157; Becker 1983, 

p. 318). 

We recognize that many of the 

ecological, physiological, and 

behavioral characteristics discussed 

here are influenced to varying extents 

by environmental factors. For example, 

fish exhibit indeterminate growth, 

where adults can reach larger sizes in 

larger habitats with more favorable 

growth conditions or greater prey 

availability, but may be more 

diminutive under less favorable habitat 

conditions (Huckins et al. 2008, p. 

1323). To this effect, many physiological 

characteristics of coasters would be 

expected to differ from their streamresident counterparts, with coasters 

being larger than residents, simply 

because coasters access the more 

productive lake environments. In 

addition, many of the characteristics we 

evaluate are interrelated, with one 

characteristic influencing or 

determining one or more of the other 

characteristics. For example, fecundity 

is largely a function of the size and 

condition of the fish. Also, prey 

selection will be influenced by the prey 

availability in different habitat types. 

We rely on all the characteristics taken 

together to describe the phenotypic 

characteristics of each type. Regardless 

of the source of the phenotypic 

characteristics of the types, be they 

controlled by genetic heritability, 

environmental influences, or both, they 

accumulate to form a description of 

each form and that defines either their 

similarity or separation. 

We further recognize that upper Great 

Lakes brook trout display a continuum 

of traits in most of the characteristics 

described. However, the range of 

overlap is small in comparison to the 

broader range of difference between the 

two forms, with the majority of adult 

coasters and stream-residents clearly 


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occupying nonoverlapping portions of 

the continuum. Further, at the end of 

the continuum of traits, coasters are 

markedly separate in their use of Great 

Lakes habitat. As we stated in adopting 

the DPS Policy in 1996, ‘‘logic demands 

a distinct population recognized under 

the Act be circumscribed in some way 

that distinguishes it from other 

representatives of its species. The 

standard established for discreteness is 

simply an attempt to allow an entity 

given DPS status under the Act to be 

adequately defined and described’’ (61 

FR 4721, at 4724; February 7, 1996). In 

the case of brook trout in the Great 

Lakes, there is a group that can be 

clearly distinguished by a variety of 

characteristics, particularly its use of the 

Great Lakes habitat, which leads to or 

results from marked separation in the 

other characteristics. 

Despite the apparent reproductive 

exchange and genetic similarity between 

stream-resident forms and coaster forms 

of brook trout, the life forms remain 

markedly separated physiologically, 

ecologically, and behaviorally. The DPS 

Policy states that ‘‘the standard adopted 

[for discreteness] does not require 

absolute separation of a DPS from other 

members of its species, because this can 

rarely be demonstrated in nature for any 

population of organisms * * * [T]he 

standard adopted allows for some 

limited interchange among population 

segments considered to be discrete, so 

that loss of an interstitial population 

could well have consequences for gene 

flow and demographic stability of a 

species as a whole’’ (61 FR 4722; 

February 7, 1996). Coasters are a group 

of organisms that can be distinguished 

from stream-resident brook trout by a 

variety of characteristics, particularly its 

migratory life strategy and use of the 

Great Lakes. 

Thus, given marked separation in 

physical, physiological, ecological, and 

behavioral factors, we conclude that the 

coaster-only population segment is 

discrete from Great Lakes streamresident brook trout. Further, as stated 

above, given its marked separation from 

all other brook trout outside of the Great 

Lakes Basin as the result of the physical 

separation between the drainage of the 

Great Lakes basin and neighboring 

drainages, the coaster-only population 

segment is discrete from brook trout 

outside the Great Lakes basin. 

Consequently, we find that the coasteronly population satisfies the element of 

marked separation under the 1996 DPS 

Policy, and is therefore considered to be 

a discrete population per our policy. 

International Border 

We presently do not find that this 

population segment of the brook trout 

on either side of the international 

United States border with Canada is 

discrete due to differences in control of 

exploitation, management of habitat, 

conservation status, or regulatory 

mechanisms that are significant in light 

of section 4(a)(1)(D) of the Act. 

Significance 

We must next evaluate whether the 

coaster brook trout population segment 

is significant to the larger brook trout 

taxon. We find that, although we 

determined that coaster brook trout are 

a discrete population segment, they cooccur with and are a subset of the same 

population as other brook trout types 

(stream residents) in the upper Great 

Lakes (see Species Information section 

above). Review of the best available 

scientific information does not suggest 

that the coaster and resident life forms 

in these populations are genetically 

distinct from each other, indicating that 

they are part of one breeding population 

(D’Amelio and Wilson 2008, p. 1221; 

Scribner et al. 2008, p. 10). Thus, 

similar to our Upper Great Lakes All 

Brook Trout population segment, the 

loss of coasters would not create a 

significant gap in the range of the taxon, 

they are not the only remaining natural 

occurrence of the taxon, and they do not 

show significant genetic distinctiveness 

in comparison to the remainder of the 

taxon. In addition, coasters occupy a 

smaller portion of the same ecological 

setting as other brook trout in the upper 

Great Lakes. Although, as discussed 

above, coasters may be important to the 

long-term viability of brook trout 

populations throughout Lake Superior, 

the relevant question is whether 

coasters are significant to the taxon as 

a whole, here, all native brook trout. 

Given this, the significance analysis 

documented for the all brook trout 

population segment (see Upper Great 

Lakes All Brook Trout DPS section 

above) also applies to the coaster-only 

population segment, and we similarly 

conclude that the coaster-only 

population segment does not meet the 

significance elements of the DPS Policy. 

DPS Conclusion—Coaster-Only 

Population Segment 

On the basis of the best available 

information, we conclude that the 

coaster-only population segment in the 

Upper Great Lakes is discrete due to 

marked separation as a consequence of 

physical, ecological, physiological, or 

behavioral factors according to the 1996 

DPS policy. However, on the basis of the 

four significance elements in the 1996 

DPS Policy, we conclude that this 

discrete population segment is not 

significant to the rest of the taxon, and 

therefore, does not qualify as a valid 

DPS under our 1996 DPS Policy. As 

such, we find that the coaster-only 

population in the upper Great Lakes is 

not a listable entity under the Act. 

Salmon Trout River/South Shore Lake 

Superior Brook Trout Population 

Segment 

This section evaluates whether the 

Salmon Trout River-South Shore Lake 

Superior brook trout population 

segment qualifies as a DPS. Since the 

Salmon Trout River contains the only 

known brook trout population with 

naturally reproducing coaster on the 

South Shore of Lake Superior, we 

addressed these two petition requests in 

one analysis. 

Discreteness 

Markedly Separate 

The brook trout population segment 

that occupies the Salmon Trout River is 

markedly separate from other members 

of the brook trout taxon because it is 

genetically or reproductively isolated. 

This physical isolation is supported by 

recent evidence from Scribner et al. 

(2008, pp. 12–13), which found no 

genetic evidence of Salmon Trout River 

fish in neighboring streams, indicating 

that Salmon Trout River coasters are not 

a source of gene flow among streams. 

International Border 

Since the Salmon Trout River 

population segment does not cross an 

international border, this basis for 

finding discreteness is not applicable. 

In conclusion, the Salmon Trout River 

brook trout population segment, as 

defined here, meets the element for 

discreteness under our 1996 DPS Policy 

and is considered discrete from the 

remainder of the brook trout taxon. This 

discreteness arises from the population 

segment’s genetic or reproductive 

isolation from the remainder of the 

taxon which is supported by evidence of 

genetic discontinuity. 

Significance 

Evidence of the Persistence of the 

Discrete Population Segment in an 

Ecological Setting That Is Unique for the 

Taxon 

The ecological setting for the Salmon 

Trout River discrete population segment 

is similar to that of other brook trout 

populations throughout the upper Great 

Lakes region. We are unaware of any 

features that make the Salmon Trout 

River unique or unusual in terms of 


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brook trout habitat. There is nothing 

about the ecological setting that is 

unique or unusual for the species, 

particularly in light of the other 

occurrences within Lake Superior. 

Consequently, this population of brook 

trout does not meet the significance 

element of this factor. 

Evidence That Loss of the Population 

Segment Would Result in a Significant 

Gap in the Range of the Taxon 

This criterion from the DPS policy 

does not apply to the Salmon Trout 

River discrete population segment 

because this population is one of 

thousands of brook trout populations 

existing throughout the range of the 

taxon and its loss would represent an 

extremely small portion of the range. 

Consequently, this population of brook 

trout does not meet the significance 

element of this factor. 

Evidence That the Population Segment 

Represents the Only Surviving Natural 

Occurrence of a Taxon That May Be 

More Abundant Elsewhere as an 

Introduced Population Outside Its 

Historical Range 

This criterion from the DPS policy 

does not apply to the Salmon Trout 

River discrete population segment 

because it is not a population segment 

representing the only surviving natural 

occurrence of the taxon that may be 

more abundant elsewhere as an 

introduced population outside its 

historical range. Consequently, this 

population of brook trout does not meet 

the significance element of this factor. 

Evidence That the Discrete Population 

Segment Differs Markedly in Its Genetic 

Characteristics From Other Populations 

of the Species 

Scribner et al. (2008, p. 9) indicates 

that Lake Superior brook trout 

populations, including the Salmon 

Trout River, are highly genetically 

structured with low levels of gene flow 

among populations. The Salmon Trout 

River contains two genetically distinct 

populations that are separated by 

impassable waterfalls (Scribner et al. 

2008, p. 10). Both populations in the 

Salmon Trout River were equally 

genetically diverged from the other 

populations included in the study 

(Scribner et al. 2008, p. 7). This pattern 

of population genetic structuring is 

common in brook trout throughout the 

species’ range because, like many 

salmonids, this species likely exhibits 

some degree of spawning site fidelity 

(Angers et al. 1999, p. 1044; D’Amelio 

et al. 2008, pp. 1347–1348; Mucha and 

Mackereth 2008, p. 1211). This degree of 

genetic divergence that forms among 

populations is reflective of the 

reproductive connections (isolation) 

among the populations across the range 

of the taxon. 

We are unaware of any information 

indicating that this population segment 

differs from the species in its genetic 

characteristics (such as exhibiting 

unique alleles or a proportion of genetic 

variability beyond the norm of 

distribution) such that it should be 

considered biologically or ecologically 

significant to the taxon based on genetic 

characteristics. Consequently, this 

population of brook trout does not meet 

the significance element of this factor. 

DPS Conclusion—Salmon Trout River/ 

South Shore Lake Superior Population 

Segment 

On the basis of the best available 

information, we conclude that the 

Salmon Trout River brook trout 

population segment is ‘‘markedly 

separated’’ from all other populations of 

the same taxon as a consequence of 

physical factors, supported by genetic 

evidence. Consequently, the Service 

concludes that the petitioned entity is 

discrete according to the 1996 DPS 

Policy. However, on the basis of an 

evaluation of the four significance 

elements of the 1996 DPS Policy, we 

conclude that this discrete population 

segment is not significant to the species 

to which it belongs. Therefore, we find 

that the Salmon Trout River brook trout 

population does not qualify as a DPS 

under our DPS Policy and is 

consequently not a listable entity under 

the Act. 

Significant Portion of the Range 

Analysis 

The Act defines an endangered 

species as one ‘‘in danger of extinction 

throughout all or a significant portion of 

its range,’’ and a threatened species as 

one ‘‘likely to become an endangered 

species within the foreseeable future 

throughout all or a significant portion of 

its range.’’ Having determined that the 

northern Great Lakes population 

segment of brook trout and the Salmon 

Trout River/South Shore Lake Superior 

populations of the coaster brook trout 

do not meet the elements of our 1996 

DPS Policy as being valid DPSs, we then 

assessed whether the upper Great Lakes 

brook trout is a significant portion of the 

range (SPR) of the native brook trout 

where the species is in danger of 

extinction or likely to become so in the 

foreseeable future. 

On March 16, 2007, a formal opinion 

was issued by the Solicitor of the 

Department of the Interior, ‘‘The 

Meaning of ‘In Danger of Extinction 

Throughout All or a Significant Portion 

of Its Range’ ’’ (DOI 2007). We have 

summarized our interpretation of that 

opinion and the underlying statutory 

language below. A portion of a species’ 

range is significant if it is part of the 

current range of the species and is 

important to the conservation of the 

species because it contributes 

meaningfully to the representation, 

resiliency, or redundancy of the species. 

The contribution must be at a level such 

that its loss would result in a decrease 

in the ability of the species to persist. 

The first step in determining whether 

a species is endangered in an SPR is to 

identify any portions of the range of the 

species that warrant further 

consideration. The range of a species 

can theoretically be divided into 

portions in an infinite number of ways. 

However, there is no purpose to 

analyzing portions of the range that are 

not reasonably likely to be significant 

and threatened or endangered. To 

identify those portions that warrant 

further consideration, we determine 

whether there is substantial information 

indicating that (i) the portions may be 

significant and (ii) the species may be in 

danger of extinction there. In practice, a 

key part of this analysis is whether the 

threats are geographically concentrated 

in some way. If the threats to the species 

are essentially uniform throughout its 

range, no portion is likely to warrant 

further consideration. Moreover, if any 

concentration of threats applies only to 

portions of the range that are 

unimportant to the conservation of the 

species, such portions will not warrant 

further consideration. 

The petition specified two portions of 

the range of brook trout: (1) The 

historical range of coaster brook trout in 

the contiguous U.S., namely the upper 

Great Lakes, and (2) the Salmon Trout 

River/South Shore Lake Superior. In our 

SPR analysis, we assessed threats to 

brook trout in these portions in 

comparison to threats acting on other 

portions of the range. Information on 

threats within the upper Great Lakes 

region included primarily habitat 

degradation, overutilization, nonnative 

fishes, and loss of connectivity and lifehistory diversity. We had comparatively 

less detailed information on the threats 

acting throughout the rest of the range. 

The best information available to us 

regarding other portions of the brook 

trout range was found in analyses 

completed for the Eastern Brook Trout 

Joint Venture (see Hudy et al. 2005, TU 

2006). Given the information available 

to us on threats to brook trout across its 

range, we conclude that threats to this 

species were similar throughout its 

range, that the conservation status of the 

species is similar throughout its range, 


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and that there is no area within the 

range of the upper Great Lakes and the 

Salmon Trout River/South Shore Lake 

Superior portions of the coaster brook 

trout where potential threats to this 

species are significantly concentrated or 

are substantially greater than in other 

portions of the range. We found no 

evidence that more threats were 

geographically concentrated within the 

upper Great Lakes than in any other part 

of the range; according to the findings 

of Hudy et al. (2005), it seems that 

threats may be greater in portions of the 

Northeastern U.S. populations than in 

the Great Lakes. 

Therefore, we find that the brook trout 

is not threatened or endangered solely 

in any significant portion of its range 

within the upper Great Lakes. As stated 

in the Finding section below, we plan 

to initiate a range-wide assessment of 

the native brook trout that will enable 

us to better understand the status of the 

native brook trout across the range of 

species, including a determination of 

whether the threats to the species, 

which are not concentrated in the upper 

Great Lakes, warrant listing the native 

brook trout rangewide. 

Finding 

In making this finding, we considered 

information provided by the petitioners, 

as well as other information available to 

us concerning coaster brook trout. We 

have carefully assessed the best 

scientific and commercial information 

available regarding the status of and 

threats to coaster brook trout in the 

upper Great Lakes. We reviewed the 

petition, and available published and 

unpublished scientific and commercial 

information. We also consulted with 

Federal and State land managers, along 

with recognized experts in conservation 

and population genetics and brook trout 

and salmonid biology. This 12-month 

finding reflects and incorporates 

information that we received from the 

public following our 90-day finding or 

that we obtained through consultation, 

literature research, and field visits. 

On the basis of this review, we have 

determined that the coaster brook trout 

in the upper Great Lakes does not meet 

the elements of our 1996 DPS Policy as 

being a valid DPS. We also find that the 

coaster brook trout is not an SPR of the 

native brook trout and does not warrant 

further consideration as such under the 

Act. Therefore, we find that the coaster 

brook trout is not a listable entity under 

the Act, and that listing is not 

warranted. 

Although we find that population 

segments analyzed above are not listable 

entities, we found enough information 

concerning the diversity, habitats, 

population structure, threats, and trends 

of the native brook trout in its entire 

range to initiate a range-wide 

assessment that will enable us to better 

understand the status of the native 

brook trout across the range of species. 

Completing a range-wide assessment 

will allow us to better evaluate if any 

population would meet the elements of 

the DPS policy or constitute an SPR of 

the taxon. We will also continue to 

assess the status of and threats to both 

the upper Great Lakes and Salmon Trout 

River/South Shore Lake Superior 

populations of the coaster brook trout. 

We request that you submit any new 

information concerning the taxonomy, 

biology, ecology, and status of the brook 

trout in its entire native range. Send this 

information to the Region 3 Fish and 

Wildlife Service Regional Office (see 

ADDRESSES section) whenever it 

becomes available. We will accept 

additional information and comments 

from all concerned governmental 

agencies, the scientific community, 

industry, or any other interested party 

concerning this finding; and will 

reconsider this determination with new 

information as appropriate. The Service 

continues to strongly support the 

cooperative conservation and 

restoration of the coaster brook trout in 

the upper Great Lakes. 

References 

A comprehensive list of the 

referenced materials is available upon 

request (see ADDRESSES section above). 

Author 

The primary authors of this document 

are staff located at the Region 3 Fish and 

Wildlife Service Regional Office (see 

ADDRESSES). 

Authority 

The authority for this action is the 

Endangered Species Act of 1973, as 

amended (16 U.S.C. 1531 et seq.). 

Stephen Guertin, 

Acting Deputy Director, U.S. Fish and Wildlife 

Service. 

[FR Doc. E9–11527 Filed 5–18–09; 8:45 am] 

BILLING CODE 4310–55–P 


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