Fisheries
Applied Research and Technical Assistance
Helena Field Office
Decision support
tools to support native fish management: tradeoffs between threats of
nonnative invasions and isolation
Habitat fragmentation and invasion of
nonnative fishes are primary contributors to the decline of native salmonids
in the western US, but attempts to ameliorate their different effects may
elicit different and often conflicting management approaches. Removal of
migration barriers to connect native populations to larger stream networks
could allow upstream invasions of nonnative fishes, while installing migration
barriers to preclude these invasions may exacerbate effects of habitat
fragmentation and population isolation. Both actions could threaten native
species and integrity of aquatic systems, but fish biologists may employ both
barrier installation and barrier removal strategies across the western US
without evaluation of the opposing threats. The potential conflicts highlight
a challenge in native fish conservation.
Our goal was to
formalize an evaluation of tradeoffs between intentional isolation, invasion
and conservation of native salmonids. We focused on persistence of native
westslope cutthroat trout (Oncorhynchus clarkii lewisi), potential
invasion and subsequent effects of nonnative brook trout (Salvelinus
fontinalis), and the primary environmental and anthropogenic factors
influencing both species and their interactions. Our objectives were to
develop and explore the application of a Bayesian Belief Network (BBN) as a
decision support tool and highlight results that provide general guidance for
biologists and managers. We focused this work on cutthroat trout and brook
trout because they represent a widespread and well defined problem in central
and northern Rocky Mountain streams (Fausch et al. 2006), but we believe our
approach can be readily adapted to other species.
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|
Figure 1 from
Peterson et al. 2008. Conceptual model depicting environmental conditions
and processes influencing persistence of westslope cutthroat trout (WCT)
and the tradeoffs between intentional isolation and invasion by brook
trout (BKT). Shaded ovals indicate input variables or nodes (prior
conditions) believed to affect WCT and brook trout populations, dashed
ovals indicate influences that originate outside the local stream network,
the rectangle for invasion barrier indicates the primary management
decision, and arrows indicate conditional relationships among variables
(nodes). The conceptual model was formalized using a Bayesian Belief
Network (BBN) implemented using the software program NETICA. |
Collaborators:
Doug Peterson (USFWS); Bruce Rieman
and Mike Young, US Forest Service Rocky Mountain Research Station; Kurt
Fausch,
Colorado State University; Jason Dunham,
US Geological Survey FRESC
Funding:
Region 1, US Forest Service
Research products:
InVAD 1.1 - BBN
decision support model. To run the model:
1. Download PDF of
users guide
2. Download free version of proprietary
NETICA software to run the model.
Note: The use of trade or firm names is for
reader information only and does not imply endorsement of the US Department of
Interior of any product or service.
3. Download the
BBN decision support model file (.zip
that will extract to .dne). Note: the .dne file
will only open after downloading NETICA
Additional model details are
presented in
Peterson et al. 2008
Related publications
Fausch, K.D., Rieman, B.E., Young, M.,
Dunham, J.B., 2006, Strategies for conserving native salmonid populations at
risk from nonnative fish invasions - tradeoffs in using barriers to
upstream movement. USDA Forest Service, Rocky Mountain Research Station
RMRS-GTR-174. (pdf)
Peterson, D.P., B.E. Rieman, J.B. Dunham,
K.D. Fausch, and M.K. Young. 2008. Analysis of trade-offs between threats
of invasion by nonnative brook trout (Salvelinus fontinalis) and
intentional isolation for native westslope cutthroat trout (Oncorhynchus
clarkii lewisi). Canadian Journal of Fisheries and Aquatic Sciences
65:557-573. (pdf)
Fausch, K.D., B.E. Rieman, J.B. Dunham,
M.K. Young, and D.P. Peterson. 2009. The invasion versus isolation
dilemma: tradeoffs in managing native salmonids with barriers to upstream
movement. Conservation Biology 23(4): 859870. (pdf)
Peterson, D.P.,
B.E. Rieman, J.B. Dunham, K.D. Fausch, and M.K. Young. 2007.
Analyzing Tradeoffs Between the Threat of Invasion by Brook Trout and Effects
of Intentional Isolation for Native Westslope Cutthroat Trout Pages 51-57 in
R. F. Carline and C. LoSapio, editors. Wild Trout IX: Sustaining wild trout in
a changing world. Wild Trout Symposium, Bozeman, Montana. (pdf)
