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Bull trout populations are lower, more variable, and declining where stream habitat is limited, invasive species and land-use (i.e., roads) are prevalent, and stream temperatures are highest, according to a new study led by the USGS.

The research identified the effects of climate, invasive species, and land-use on long-term population dynamics on 92 populations of bulltrout in in Montana, Idaho, and British Columbia. 

Although invasive fishes have strong negative effects on bull trout, proactive gill net suppression of lake trout appeared to positively benefit bull trout populations. These data emphasize that climate warming will increase vulnerability of cold water specialists like bull trout, yet other human stressors – especially invasive fishes – are immediate threats that can be addressed by proactive management actions.

Most research addressing the consequences of climate change on cold-water fish has generally focused on how stream temperature impacts where they are found.  This study addresses how climatic variation influences fish populations in the context of other additional stressors.  

The paper, “Climate, invasive species and land use drive population dynamics of a cold-water specialist” can be found HERE.