Seasonal Movements of Brown Trout in Onondaga Lake, New York

Onondaga Lake is a recovering hypereutrophic lake located in central New York State. In recent years, with increasing water quality, there has been a return of several coldwater fish species. This study examined the ways in which brown trout (Salmo trutta) utilize the lake and its tributaries in relation to temperature and dissolved oxygen. Six large (>400mm) brown trout were tracked biweekly using sonic telemetry from May to September, 2011. This, in conjunction with gill net data, was used to ascertain movement patterns throughout the summer. Preliminary results indicate a correlation between hypolimnetic oxygen, epilimnetic temperature, and the presence of brown trout in Onondaga Lake. In late June, as epilimnetic temperatures increased and hypolimnetic oxygen decreased, trout were forced to seek refugia outside of the lake. One implication of this is that space and food availability are most likely limited in the tributaries relative to the lake. Therefore, the productivity and spatial constraints of the tributaries may be directly limiting the lake’s potential to support a large coldwater fishery. Research on the return of this species will provide a better understanding of the recovery of this system, which will in turn give managers information necessary for reintroducing native coldwater species.