Modeling the Lake-Wide Sustainability of Lake Trout Stocks in Lake Superior

Following the recovery of lake trout stocks in Lake Superior due to stocking, sea lamprey control, and harvest regulations, agencies developed statistical catch-at-age (SCAA) models to determine if accepted total annual mortality rates were sustainable.  The developed SCAA models assumed that immigration and emigration rates among stocks were equal and could thus be ignored.  Lake Superior is divided into individual management units, each of which has been treated as a separate stock.  Recent studies of lake trout movement have shown that immigration and emigration among stocks are not equal (Kapucinski et. al 2005).  In our study, SCAA models are used to develop simulation models that include movement rates to determine future sustainability of lake trout stocks assuming movement.  We expect to find that emigration will not equal immigration, that movement among sub-stocks will alter the population dynamics of other stocks, and that the WI-2 stock functions as a source for other stocks.  If this is true, Lake Superior lake trout may be more sustainable if managed as a meta-population rather than as individual stocks.