May 9, 2014
Eastern Brook trout have been swimming the ancient Appalachian valleys for millions of years. The fish are known for their aesthetic beauty—which can feature all shades of the rainbow. But this beauty is sensitive. It needs exceptionally clean and very cold water to survive. So it's expected to be an early casualty of climate change.
Climate change isn't the first big challenge the fish has faced.
"From probably, you know, the best historical records we have, over there in Pennsylvania, brook trout have probably been completely eliminated from about a third of the watersheds that they historically occurred in," says Jack Williams, chief scientist with the conservation group Trout Unlimited. "And about another third, they've been greatly reduced.
What's reduced the populations? Changing land use—like logging trees that shade the cold-water streams they need. Agriculture, coal mining, and, lately, Marcellus shale gas development, have also played roles.
Newer threats to brook trout include invasive species. Brown trout, which are nonnative to the continent, and some types of bass, catfish, and chubs can tolerate warmer temperatures so they can outcompete the brook trout as temperatures rise.
Pennsylvania's most recent update of its Climate Impacts Assessment, released in the fall, points out that eastern Brook trout is a recreationally and culturally important species that requires habitat mitigation efforts.
Trout Unlimited partners with Pennsylvania's Fish & Boat Commission and organizations like the Eastern Brook Trout Joint Venture to study and conserve trout habitat.
"We're working on the big policy issues...trying to reduce our carbon footprint and trying to reduce the problems of climate change in the future," Williams says. "But we're also focusing on the present.... And with climate change and things like brook trout, we know how important it is to have clean water, to have streams that have deep pools, for instance, that provide some sort of a cold water thermal refuge for these fish, the importance of riparian vegetation, that is, the vegetation that kind of grows along the stream. We have to make sure there's good trees, good shade that helps keep the water cool. So a lot of the stream restoration we work on now has a climate change component."
Williams believes there's reason for hope when it comes to eastern Brook trout and climate change.
"Climate change can be so daunting, and when you really start to read about it and understand it, it's pretty overwhelming and pretty negative," he says. "And that's truly the way it is. But I think there are some things that we can do to help out our fish and wildlife populations and to help ourselves out, too. And, I think some of these stream restoration treatments are kind of examples of that. I think it's really good for people to understand that it isn't all doom and gloom—that there are some things we can do about climate change and that there are some organizations like Trout Unlimited that are working hard in that direction."
Map indicates distribution of B?rook trout status classifications in subwatersheds throught the species' eastern U.S. range and a 50-km buffer zone. Research by American Fisheries Society.