dangers of extinction to the species? Plaintiffs contest that the
inclusion of hybrid stock numbers in the WCT population count is per se
unreasonable, while defendants argue that the ESA does not mandate that
only genetically pure fish be counted in determining the species'
status. This Court defers to the policy judgments of FWS in weighing
hybridization as one of many factors, but finds that FWS' rationale for
the inclusion of hybrid fish in the population identified for evaluation
in the Status Review is unsupported by the administrative record.
Hybridization as a Threat
In their pleadings, both FWS and plaintiffs view hybridization of WCT
as a potential threat to the trout population. They disagree as to the
weight that should be given to this threat. The Court should remand an
agency finding where the conclusions are arbitrary and capricious, or
where the agency failed to consider relevant information or factors.
Plaintiffs protest that the administrative record clearly identifies
hybridization as the greatest single threat. See Status Review at 20,
93, 158; AR 407-08; Liknes and Graham, A.R. 5977. Plaintiff relies on the
record in identifying several significant harms stemming from
hybridization, including impairment of "growth, survival, fertility,
developmental rate, and the ability of individuals to develop properly."
See A.R. 855; A.R. 2386 (Allendorf & Leary article). FWS recognized that
the best available science indicates that hybridization constitutes a
significant threat to WCT. See Status Review at 20, 158.
However, as a factor affecting the WCT's continued existence, FWS was
required to consider whether the threat of hybridization was sufficient
to warrant listing of WCT as a threatened or endangered species.
16 U.S.C. § 1533(a)(1)(E).
In its Status Review, FWS identified hybridization as an ongoing threat
in each of the 15 watersheds occupied by WCT. Yet, the record is devoid
of any evidence that the agency evaluated that threat in considering
whether the WCT population was viable.
Defendants assert that the Service extensively considered the issue of
hybridization and "reasonably determined that, while it conceivably can
pose a threat to WCT, any such threat that exists today does not rise to
the level of indicating that the WCT subspecies as a whole is in danger
of extinction throughout all or a significant portion of its range, or is
likely to become an endangered species throughout all or a significant
portion of its range. . . ." Defendants rely on a FWS draft Intercross
policy addressing genetic introgression and a scientific study indicating
that at least some degree of hybridization would not threaten WCT. Yet,
the draft Intercross policy in no way indicates what degree of
hybridization would threaten WCT, or that the existing levels of
hybridization do not currently threaten WCT.
Inclusion of Hybrid Stock in the WCT Population Considered for Listing
The agency's justification of its listing decision is arbitrary not
because it fails to consider hybridization as a threat but because
— once identifying hybridization as a threat — the agency
includes hybrid fish in the population considered for listing. If
hybridization is a "threat" to the species, it would seem logical that
hybrid stock should not be included in the population of WCT reviewed for
The administrative record wholly fails to address the implications of
including hybrid stock in the "population." In evaluating the health of a
species' population, FWS is required to consider whether the species is
likely, in the foreseeable future, to become endangered or extinct
throughout all or a significant portion of its range.
16 U.S.C. § 1532(6), 1532 (20). In order to make its determination as
to whether an ESA listing for WCT was warranted, FWS was required to
identify the WCT population*fn2 and then consider the best available
scientific data concerning the threats to the population and its
habitat. Consequently, the identification of the potentially viable
— or endangered — population is vital to ultimate listing
The FWS has defined "population" as "a group of fish or wildlife . . .
in common spatial arrangement that interbreed when mature."
50 C.F.R. § 17.3. Plaintiffs' petition identified "remaining,
genetically pure stocks of WCT" as warranting listing consideration. 65
Fed. Reg. 20120, 20120 (emphasis added). FWS explained its identification
of the relevant WCT population:
Throughout the historic range of WCT, few of the
remaining WCT stocks have been genetically classified
on the basis of chromosome counts, biochemical
characteristics, or molecular genetic information.
Although application of such genetic techniques for
characterizing fish stocks is becoming more common
today, in most cases the taxonomic classification of
extant WCT stocks has been based largely on the
spotting patterns shown by the fish and the
professional judgments and experiences of the fishery
biologists who examined the fish in the field.
Although WCT stocks with varying degrees of genetic
purity are known to occur across the subspecies'
range, there is currently little definitive
information on the genetic characteristics of most WCT
stocks (U.S. Fish and Wildlife Service 1999). Even in
Montana, where an extensive database on the genetic
characteristics of many WCT stocks exists, the precise
genetic characteristics of most stocks are unknown.
Consequently, we based the WCT status review on the
professional judgments made by the State game and fish
departments that the fish the departments classified
as WCT actually represented the subspecies, even
though the precise genetic characteristics of those
stocks may not be known, or the stocks may consist of
intercross progeny that were the product of some low
or nondetectable level of interbreeding between WCT
and another fish species.
Status Review, 65 Fed. Reg. 20120, 20121. Defendants explain that hybrid
stock — those whose genetic make-up was unknown and those with low
levels of hybridization — was included in the WCT stock reviewed
for listing because few of the remaining WCT stocks have been genetically
classified. 65 Fed. Reg. 20120, 20120.