Brook Trout Genetics

Monday, August 30, 2010 - 10:23pm


Sam Walker
Although I am back at school at Colgate University now, I will continue to update the blog to provide more information on what the Henry's Fork Foundation interns got up to this summer. The second-biggest project we worked on in addition to the Caldera Project tributaries study was collecting brook trout genetic samples for Trout Unlimited. This project started when TU approached the Foundation and requested that we help them out for a project seeking to assess the genetics of the invasive brook trout in the streams of eastern Idaho.

You may wonder why researchers care about the genetic quality of brook trout when it is the pure strain of yellowstone cutthroat that most anglers are after. However, in our long term monitoring of many different streams in the Henry's Fork watershed, the foundation has found that some streams can support both yellowstone cutthroat and brook trout without the brook trout ever completely taking over the area and wiping out the native cutthroats. On the other hand, some streams have seen the brook trout completely out-competing the native trout. While many factors could be at play here, it would be interesting to see if the genetic stock of the trout has any affect on the balance of species in these streams, i.e. if one (or a few) particularly well-suited groups of brook trout are capable of wiping out cutthroat while other less well-adapted brookies are not able to fully invade. This project will help to establish the genetics of the brook trout in the watershed and will hopefully help further the Foundation's goal of promoting the health and abundance of wild cutthroat.

To undertake this project the intern crew and Anne Marie Emery-Miller traveled to four widely distributed and ecologically varied streams within the watershed in order to collect a sample of brook trout from a wide range of habitats. The streams we visited included the East Fork of Dry Creek, Targhee Creek, Warm Springs Creek, and Squirrel Creek. Over a number of days we visited these sites and collected 35 brook trout from each stream, with around 10 fin clips being taken at each site. This method allowed us to gather a useful collection of genetic material for analysis by Trout Unlimited. Hopefully the results from this study will contribute to furthering the Foundations goals in the future. Check out the sites from this study in Google Earth and look at our photos from this project at our Picasa page (links also on the right-hand sidebar). Stay tuned for more news about the summer crew's work.