Changes in Wisconsin's Lake Michigan Salmonid Sport Fishery, 1969-1985

Abstract
The modern sport fishery for salmonids in Wisconsin waters of Lake Michigan was begun during 1963-1969 with the stocking of rainbow trout Oncorhynchus mykiss, lake trout Salve/inns namaycush, brook trout 5". fontinalis, brown trout Salmo trulta, coho salmon O. kisutch, and Chinook salmon O. tshawytscha. The fishery grew rapidly during 1969-1985 as angler effort increased 10-fold, catch rate doubled, and catch increased 20-fold. The stocking and catch became increasingly dominated by Chinook salmon, with coho salmon and lake trout of secondary im- portance, and brown, rainbow, and brook trout of least importance. Trolling dominated the fishery, particularly by launched-boat anglers and, more recently, by moored-boat anglers. Charter boat trolling grew the most continuously and had the highest catch rates. The catch by trollers was dominated by Chinook and coho salmon and lake trout. Pier, stream, and shore anglers fished less overall, but had catch rates that were similar to launched-boat anglers. The catch by pier and shore anglers was spread among chinook and coho salmon, and lake, brown, and rainbow trout. The catch by stream anglers was dominated by chinook salmon. The percentage of stocked fish that were subsequently caught (catch ratio) was highest for fingerling chinook salmon (12.9%). Yearling brook trout, brown trout, coho salmon, lake trout, and rainbow trout had intermediate catch ratios (5.1-9.8%). Fingerling brook trout, brown trout, and lake trout had the lowest catch ratios (2.5- 3.5%). The catch ratio for rainbow trout dropped from 9.8 to 5.1% after stocking with a different strain (the Shasta strain). Fingerling rainbow trout produced the lowest returns (< 0.5%). We derived stocking recommendations for each species and life stage based on these catch ratios, and catch objectives based on maintaining catch levels recorded during 1983-1985. Lake Michigan fish populations have changed whitefish C. clupeaformis declined in number or dramatically in recent decades. For more than 100 became extinct. years before 1940, fish populations in Lake Mich- State and federal fisheries management agencies igan supported relatively stable sport and com- around Lake Michigan began intensive efforts in mercial fisheries. During the 1940s and 1950s, the 1960s to control sea lampreys, through chem- however, dramatic changes in the Lake Michigan ical treatment of larval nursery areas, and ale- fish community resulted from invasions by the wives, through stocking of salmonid predators, exotic sea lamprey Petromyzon marinus, rainbow Subsequently, sea lamprey populations were sub- smelt Osmerus mordax, and alewife Alosa pseu- stantially reduced and a sport fishery for trouts doharengus', increased commercial fishing pres- Salmo spp., chars Salvelinus spp., and Pacific sure; and deterioration of spawning habitat. Many salmon Oncorhynchus spp. was developed. This native species, including lake trout Salvelinus fishery continues to the present and now represents namaycush, ciscoes Coregonus spp., and lake a multimillion-dollar tourist industry for many of ____

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