Size-Limit Regulation of Sport Fishery Harvest of Lake Trout

Commercial over-harvest, sea lamprey predation, habitat degradation, and non-native species together contributed to the demise of lake trout in Lake Ontario.  By the 1950s, lake trout were nearly gone.  In the early 1970s, mangers began sea lamprey control in Lake Ontario tributaries and subsequently renewed their stocking efforts   The case history of New York’s lake trout restoration program in Lake Ontario during the 1980s-1990s provides an example of the successful use of size regulation to curb excessive angler harvest within the sport fishery.  Originally, the primary harvest control was through a creel limit of three fish.  For the 1988 season, the lake trout bag limit was set as two fish, only one of which could be between 25 and 30 inches in total length.  At the close of the 1988 fishing season, the effect of the slot limit on harvest was dramatic.  Harvest was reduced 62% from nearly 90,000 lake trout in 1987 to 35,000 fish, well below the 60,000 harvest target.  In response to angler pressure, the slot size was narrowed to 27-30 inch slot-size limit, and in 1990, 81,000 lake trout were harvested, exceeding the harvest objective by 21,000 fish or 35%.  The experience in Lake Ontario demonstrated that slot size limits can be effective in reducing harvest; however, the attitude of anglers can have a profound effect on the eventual harvest outcome.  The slot-size regulations had the unintended consequence of shifting angling effort away from, and later toward, lake trout, causing first under-harvest followed by over-harvest.