Fish Community Structure, Biomass, and Production in the Turkey Lakes Watershed, Ontario

Abstract

The Turkey Lakes Watershed contains four lakes, and the headwater lake (Batchawana Lake) consists of two distinct basins, neither of which supports a native, reproducing fish stock. Fish biomass varied by a factor of 3.3 among the other three lakes in the watershed. Fish flesh production varied by a factor of only 1.5 in the system. Salmonid and small cyprinid contribution to biomass and production increased with progression downstream. Both fish biomass and production per unit surface area decreased with increasing lake depth. The fish biomass and production in the watershed was strongly influenced by depth, but alkalinity and phytoplankton carbon assimilation also were related to stock and production. Wishart Lake, immediately below Batchawana Lake, has a fish stock with restricted recruitment, and cyprinids make only a limited contribution to the observed production. Although both these conditions may be symptomatic of lake acidification, it is unclear whether the situation in this watershed results from lake acidification or biogeographic factors.