Exotic salmonid removal (ESR) project 2010 annual report

Leonard, Jill

The Exotic Salmonid Removal project continued in 2010 with the goal of evaluating the impacts of non-native salmonid fishes on the native brook trout population in Pictured Rocks National Lakeshore. 2010 was the third full year of the project and saw the removal of nearly 1700 exotic fish, primarily juvenile steelhead trout and coho salmon, from Sevenmile Creek. During this year, in addition to the faculty P.I. for the project at Northern Michigan University, 8 graduate students, over 20 undergraduate students, 1 technician and several National Park Service employees participated in the field aspect of the project; additional undergraduate students are assisting with diet analysis and other aspects of the project in the lab. We continued to evaluate the effects of this activity on the population size, growth and condition, and feeding ecology of the fish. The population estimates of brook trout in the system are highly variable, likely reflecting the annual variability in the system as well as the relatively small population sizes involved. We have characterized the variability in growth and condition in the system and are now evaluating our data for differences between the experimental stream and the reference stream. We have conducted extensive sampling of available forage in the Sevenmile Creek. We have previously documented diet overlap between the juvenile salmonids in the system and are now able to evaluate the importance of particular diet items based on both abundance in the gut and contribution to the biomass of the gut contents. This year we also implemented a sampling strategy to assess the importance of benthic food supplies to the salmonids, although sample analysis is still ongoing. In addition to providing initial data summaries, we have also described the initiation of a geographic information systems approach to habitat use and plans for the final year of the project, 2011.