GEOGRAPHICAL DISTRIBUTIONS OF LAKE TROUT STRAINS STOCKED IN LAKE-ONTARIO

Geographical distributions of lake trout (Salvelinus namaycush) stocke d at seven locations in U.S. waters and at four locations in Canadian waters of Lake Ontario were determined from fish caught with gill nets in September in 17 areas of U.S. waters and at 10 fixed locations in Canadian waters in 1986-95. For fish of a given strain stocked at a gi ven location, geographical distributions were not different for immatu re males and immature females or for mature males and mature females. The proportion of total catch at the three locations nearest the stock ing location was higher for mature fish than for immature fish in all 24 available comparisons (sexes combined) and was greater for fish sto cked as yearlings than for those stocked as fingerlings in all eight c omparisons. Mature fish were relatively widely dispersed from stocking locations indicating that their tendency to return to stocking locati ons for spawning was weak, and there was no appreciable difference in this tendency among strains. Mature lake trout were uniformly distribu ted among sampling locations, and the strain composition at stocking l ocations generally reflected the stocking history 5 to 6 years earlier . Few lake trout moved across Lake Ontario between the north and south shores or between the eastern outlet basin and the main lake basin. L imited dispersal from stocking sites supports the concept of stocking different genetic strains in various parts of the lake with the attrib utes of each strain selected to match environmental conditions in the portion of the lake where it is stocked.