Impact of Mysis relicta on Flathead Lake

Rather than providing the expected forage for kokanee salmon in Flathead Lake, opossum shrimp proved to be a favorite food for juvenile lake trout and lake whitefish. The shrimp proved to be unavailable to the kokanee. Mysis also competed with kokanee and cutthroat trout for copepod and cladoceran zooplankton, a favored food source. The result was an abrupt decline in the numbers of kokanee, an increase in lake trout and lake whitefish and subsequent declines in cutthroat and bull trout populations.

For more information see: Spencer, C.N, Riley McClelland, and Jack Stanford, 1991. Shrimp Stocking, Salmon Collapse, and Eagle Displacement. BioScience Vol. 41 No. 1