What Drives Variability in Size of Harvested Salmonines in Southwestern Lake Michigan?

Size of harvested fish is an important aspect of recreational fisheries, and may be influenced by ecological (e.g., fish growth rates) and human (e.g., selective harvest) factors. Five primary species (Coho salmon, Oncorhynchus kisutch; Chinook salmon, O. tshawytscha; lake trout, Salvelinus namaycush; rainbow trout, O. mykiss; and brown trout, Salmo trutta) comprise the Lake Michigan salmonine fishery. As each species exhibits a different life history, size composition of the harvest can be influenced by species composition in the harvest as well as by variation in sizes within species. The invasion and proliferation of several nonindigenous species has resulted in large changes to the Lake Michigan food web, which has the potential to impact size of harvested fish via changes in growth of salmonines. While Chinook salmon have been a focus of assessment and management lake-wide, other species (e.g., Coho salmon) are less studied, despite often comprising a greater proportion of salmonine harvest in the Illinois waters of Lake Michigan. We use 33 years of annual creel survey data to explore patterns and trends in size of harvested salmonines in the Illinois waters of Lake Michigan. We investigate potential drivers of these patterns, including fishing effort, ecological variables, and meteorological conditions.