Fisheries
Applied Research and Technical Assistance
Helena Field Office
Modeling
suppression of nonnative brook trout to benefit native cutthroat trout
Nonnative trout species are among the
most significant threats to persistence of native inland salmonids, such as
cutthroat trout (Oncorhynchus clarkii spp.). Early detection of
nonnative trout invasions and subsequent eradication is the preferred
management alternative to deal with this threat, but sometimes eradication is
not possible for technical or socio-political reasons. In such cases,
maintenance control or suppression of nonnative species using mechanical
methods (e.g., electrofishing) becomes a frequent alternative where the risk
of inaction is unacceptable.
|
Colorado River
cutthroat trout |
Brook trout |
|
We conducted a
population modeling project to help biologists design and implement
effective electrofishing suppression programs. To do this we built
stage-based, stochastic matrix models describing sympatric populations
of stream-resident brook trout (Salvelinus fontinalis) and
cutthroat trout and used the models to show the demographic differences
between the species and compare the efficacy of various electrofishing
treatments for suppressing brook trout. The models were used to assess
the population response of cutthroat trout to brook trout suppression as
a function of the frequency and temporal distribution of annual
suppression visits, electrofishing intensity (number of passes) during
individual suppression events, electrofishing capture efficiency, and
immigration by brook trout. |
 |
Project investigators and Funding:
Dr. Doug Peterson (US Fish and Wildlife Service), Dr. Kurt Fausch (Colorado
State University), Dr. Rick Cunjak (Canadian Rivers Institute, University of
New Brunswick), and Dr. James Watmough (Department of Mathematics, University
of New Brunswick)
Research products:
Peterson, D. P., K. D. Fausch, J. Watmough,
and R. A. Cunjak. 2008. When eradication is not an option: modeling
strategies for electrofishing suppression of nonnative brook trout to foster
persistence of sympatric native cutthroat trout in small streams. North
American Journal of Fisheries Management 28:1847-1867. (pdf)
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