USGS Banner

Project ID: 2006MT92B

Title: Impacts of beaver on invasion ecology of brook trout (salvelinus fontinalis)

Project Type: Research

Start Date: 03/01/2006

End Date: 12/31/2007

Congressional District: At large

Focus Categories: Conservation, Ecology, Invasive Species

Keywords: beaver, brook trout, casto canadensis, cutthroat trout, Oncorhynchus clarki, Salvelinus fontinalis

Principal Investigators: Eby, Lisa; McCaffery, Magnus

Federal Funds: $15,000

Non-Federal Matching Funds: $30,000

Abstract: As a keystone species, beaver promote the creation and maintenance of wetland areas, provide complex habitat for wildlife and fish, improve water quality, and augment late season flows. Beaver ponds create excellent juvenile rearing and overwintering fish habitat resulting in substantial benefits to native fish species (8, 19). Promoting beaver either through natural population expansion or active transplantation for watershed restoration purposes is gaining favor with some landowners and managers, but is a very controversial strategy. Aside from direct human-beaver conflicts such as flooding of agricultural lands and damming of irrigation systems (8), there is also the possibility of negative effects on native fish such as, barrier creation and the potential of beaver ponds to facilitate invasion by exotic fish species. In Montanan streams, brook trout are an exotic species whose invasion often displaces native cutthroat trout through competitive interactions (37). Even though many of Montana's native species often benefit from beaver ponds, it has also been suggested that the more pool-adapted and temperature tolerant brook trout have a competitive edge in beaver ponds over more riffle-adapted colder water species (8, 15). Use of these habitats as "source" populations may then enable their colonization of colder "sink" habitats, thus sustaining invasions across a larger range (37, 41). Beaver ponds may therefore (i) be detrimental to natives through the creation of warmer, pool habitat that gives brook trout a competitive advantage, or (ii) act as a buffer, facilitating coexistence of both species by adding habitat size and complexity. The proposed research will examine whether beaver ponds mediate brook westslope cutthroat trout interactions. First, we will begin to mechanistically examine if and how beaver ponds may mediate brook trout invasions across southwestern Montana and influence interactions with westslope cutthroat trout. Seasonal sampling and mark-recapture efforts will allow us to determine whether streams with beaver ponds affect overlap between brook trout and westslope cutthroat trout distributions, alter brook trout and cutthroat trout abundances, and influence juvenile trout growth rates in streams with beaver ponds over those without. Secondly, given the potential importance of temperature as a driving factor, we will examine whether beaver ponds alter stream temperatures. We predict that beaver impoundments will increase temperatures at and below the impoundment. This question will be answered by deploying a series of temperature loggers in streams with and without beaver ponds.

Progress/Completion Report, PDF

U.S. Department of the Interior, U.S. Geological Survey
Maintained by: John Schefter
Last Updated: Thursday, January 03, 2008
Privacy Statement || Disclaimer
|| Accessibility