Brook Trout Interactions with Beaver Ponds & Dams

Abstract

A brief summary of the known relationship of brook trout and beavers.

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Free to Use or Share University of Wyoming 2022 DOI: 10.13140/RG.2.2.20760.67846/1
Brook Trout Interactions with Beaver Ponds & Dams Prepared by Andrew Lahr & Niall Clancy
Background
Beaver restoration and mimicry is growing in
popularity as a means of “low-tech” stream restoration.
a
Beaver restoration is the technique of trapping and
translocating nuisance beavers to areas where dam
building is expected to be beneficial.
b
Beaver mimicry is
the process of building beaver dam analogs (BDAs) to
provide some of the same benefits of real beaver dams.
Both real and analog beaver dams create ponded habitat
that has numerous benefits for riparian vegetation &
wildlife and helps prevent channel downcutting. Some
species of fish thrive in beaver ponds. Where those
species are native, this can be a potential benefit. Where
those species are invasive, beaver ponds may increase
that species’ abundance to a degree that harms native
species. Below is a summary of current knowledge
regarding the potential for beaver ponds to increase
Brook Trout (Salvelinus fontinalis) populations.
Summary of Reports
Like other trout, the known relationships of beavers
and Brook Trout are highly variable. Large numbers of
both positive and negative relationships exist.
Positive Relationships
Brook Trout, like Bull Trout and Cutthroat Trout, often
overwinter in beaver ponds to escape anchor ice and
conserve energy.
c
,
d
Beaver ponds also increase the total
amount of forage for Brook Trout and other species.
e
,
f
,
g
,
h
Beaver ponds tend to be good foraging & rearing habitat
for Brook Trout where dissolved oxygen is not limiting.
i
Beaver impoundments and dam analogs have also been
associated with increased groundwater recharge and
subsequent downstream recharge of cooler groundwater,
which may benefit cold-water fishes in some systems.
j
Negative Relationships
While the opposite occurs in some locations, beaver
ponds can increase stream temperatures in others.i This
can be a negative for Brook Trout if the stream is already
near their upper thermal limit, but it isn’t necessarily a
problem if the stream is generally cool or fed largely by
a
See Goldfarb, B. 2018. Eager. Chelsea Green Publishing, Hartford.
b
See beaver.restoration.usu.edu
c
Lindstrom, J. & W.A. Hubert. 2004. N AM J FISH MANAG.
DOI: 10.1577/M03-223.1
d
Jakober, M.J. et al. 1998. TRANS AM FISH SOC. DOI: 10.1577/1548-
8659(1998)127<0223:ROSIOF>2.0.CO;2
e
Cook, D.B. 1940. J MAMMAL. DOI: 10.2307/1374874
f
Rupp, R.S. 1955. TRANS AM FISH SOC. DOI: 10.1577/1548-
8659(1954)84[75:BRITHO]2.0.CO;2
g
Huey, W.S. & W.H. Wolfrum. 1956. PROG FISH CULTUR. DOI:
10.1577/1548-8659(1956)18[70:BRINM]2.0.CO;2
groundwater.h Upstream passage for trout is certainly
limited by beaver dams to some degree (particularly in
streams where drought limits the depth of upstream and
downstream pools of dams), but most studies of passage
are speculative and/or unable to determine the difference
between selection of habitat immediately below dams
and blockage of upstream movement.
k
Where quantified,
Brook Trout seem to pass beaver dams in relatively high
proportions
l
– less than Cutthroat Trout but more than
Brown Trout.
m
Depending on the type of habitat that is
flooded and age of the beaver dam, dissolved oxygen can
become limiting at certain times of year within the
pond.e,h,i
Conclusion
• We find little evidence for the assertion that
Brook Trout are uniquely benefited by beaver
ponds in comparison to other salmonids
• Both positive and negative effects of beaver
ponds exist and are highly site-dependent
• The degree to which BDAs may benefit Brook
Trout more than other species is hypothetical
and the topic of current investigation, but it is
more likely in streams where Brook Trout are
already the dominant species
Andrew Lahr – PhD candidate at the University of Montana,
Department of Ecosystem & Conservation Sciences
Niall G. Clancy, MS – PhD student at the University of Wyoming,
Wyoming Cooperative Fish & Wildlife Research Unit
h
Johnson-Bice, S. et al. 2018. N AM J FISH MANAG. DOI:
10.1002/nafm.10223
i
Renik, K.M. & A.W. Hafs. 2020. N AM J FISH MANAG. DOI:
10.1002/nafm.10422
j
Weber N., et al. 2017. PLOS One. DOI: 10.1371/journal.pone.0176313
k
Wolf, J.M. et al. 2022. bioRXiv. DOI: 10.1101/2022.09.10.507435v1
l
Benson, R.L. 2002. Univ. of Montana, thesis.
scholarworks.umt.edu/etd/6982
m
Lokteff, R.L. et al. 2013. TRANS AM FISH SOC. DOI:
10.1080/00028487.2013.797497
Photo: USFWS Southeast Region
(CC-BY)