Assessing tradeoffs in commercial harvest of Lake Huron's cold-water fish community

Lake trout (Salvelinus namaycush), lake whitefish (Coregonus clupeaformis), and bloater (Coregonus hoyi) constitute the majority of commercial harvest in Lake Huron’s cold-water fish community. Lake trout were nearly extirpated from Lake Huron in the mid 1900s. Rehabilitation efforts are ongoing and have contributed to increased observations of wild production of lake trout. Currently, lake trout harvest primarily is from bycatch in the lake whitefish fishery, setting up potential tradeoffs between harvest of lake whitefish and restoration of lake trout. Predation by lake trout on the commercially harvested bloater presents additional tradeoffs. Substantial changes to the food-web of Lake Huron over time complicate the analysis of these tradeoffs. An ecosystem model was built using the Ecopath with Ecosim software to assess the performance of alternative harvest policies on Lake Huron’s cold-water fish community. This software considers both direct (fishing) and indirect (food-web) interactions. Results from policies based on different levels of lake whitefish fishing pressure and associated lake trout total mortality are presented, and the influence of alternative hypotheses about food-web structure and ecosystem productivity are explored.