Fisheries
Applied Research and Technical Assistance
Helena Field Office
Population genetics of
bull trout in Warm Springs Creek, upper Clark Fork River, Montana
|
Bull trout in Warm
Springs Creek, Montana |
Twin Lakes Creek,
tributary to Warm Springs Creek |
The Clark Fork River system west of the
Continental Divide in Montana historically contained one of the largest
metapopulations of bull trout (Salvelinus confluentus) throughout the
species range. Warm Springs Creek contains the most-upstream population of
Federally-threatened bull trout in the Clark Fork River system. Since the
early 1900s bull trout habitat within the Warm Springs Creek drainage has been
extensively fragmented by water development and associated control structures
resulting in isolation of bull trout populations in Twin Lakes and Storm Lake
Creeks (Figure 1). Bull trout from Storm Lake and Twin Lakes Creeks may also
be entrained into Silver Lake, a reservoir which receives water diverted from
those two streams. Presence of nonnative brook trout, which can both compete
and hybridize with bull trout, may represent an additional threat to bull
trout in the Warm Springs drainage.
 |
|
Figure 1.
Warm Springs Creek drainage in western Montana, USA. In 2008, bull
trout tissue samples were collected in Storm Lake Creek, Twin Lakes
Creek, upper and lower Twin Lakes, Barker Creek, Foster Creek, Warm
Springs Creek, and Silver Lake. Myers Dam is a barrier to upstream
passage by fishes. Diversion structures on Storm Lake Creek and Twin
Lakes Creek (upstream from the aqueduct effectively isolate these
habitats from the mainstem Warm Springs Creek. Map by Dan Brewer, USFWS. |
The US Fish and Wildlife Service’s 2002
Draft Bull Trout Recovery Plan identifies the collection of genetic data as a
priority for recovery planning in many watersheds, but no baseline genetic
data were available for bull trout populations in the Warm Springs Creek
drainage. Given this, we used genetic makers (microsatellite DNA) to: (a)
characterize genetic diversity both within and among remnant bull trout
populations in the Warm Springs Creek drainage; and (b) use genetic population
assignment techniques to assign individuals of unknown origin entrained in
Silver Lake to their most likely population of origin.
In 2008 we collected tissue samples (finclips)
from bull trout in various locations in the watershed (Figure 1). Genetic
analyses were conducted by the Conservation Genetics Lab at the US Fish and
Wildlife Service’s Abernathy Fish Technology Center, in Washington state. The
data show low levels of genetic variation for bull trout within different
tributaries of Warm Springs Creek, likely as a result of population isolation;
small effective population sizes; and restricted gene flow among populations (DeHaan
et al. 2009). Silver Lake entrains bull trout from Storm Lake Creek, and bull
trout ´
brook trout hybrids were detected in Warm Springs Creek, upper and lower Twin
Lakes, and in Silver Lake.
Project report:
DeHaan, P., L. Godfrey, D. Peterson, and D. Brewer. 2009. Bull trout
population genetic structure and entrainment in Warm Springs Creek, Montana.
Abernathy Fish Technology Center, US Fish and Wildlife Service, Abernathy,
WA. (download
report)
Revised
Project Report*: DeHaan, P., L. Godfrey, D. Peterson, and D. Brewer.
2010. Bull trout population genetic structure and entrainment in Warm
Springs Creek, Montana. Abernathy Fish Technology Center, US Fish and
Wildlife Service, Abernathy, WA. (dowload
report)
* Note: The revised report includes data from a sub-population
of bull trout in the West Fork Warm Springs Creek, and summarizes
information on occurrence first generation hybrids between bull trout X
brook trout.
Funding:
NorthWestern Energy
Collaborators:
Pat DeHaan and Linda Godfrey, Abernathy Fish Technology Center – US Fish and Wildlife Service;
Dr. Doug Peterson (USFWS);
Dan Brewer (USFWS); Montana
Fish, Wildlife and Parks; USDA Forest Service; and USDA Natural Resources
Conservation Service
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