INTRODUCTION OF LAKE TROUT (SALVELINUS-NAMAYCUSH) TO INLAND LAKES OF ONTARIO, CANADA - FACTORS CONTRIBUTING TO SUCCESSFUL COLONIZATION

We evaluated the success of 183 introductions of lake trout (Salvelinu s namaycush) in small inland lakes in Ontario, Canada. Our purpose was to identify variables associated with successful versus failed natura l recruitment after introductions of hatchery-reared lake trout. Origi n of donor stocks, angling regulations, geophysical and water quality characteristics, and fish species presence-absence of the recipient la kes were evaluated as possible factors contributing to colonization su ccess. Origin of donor stock had some minor influence on the success o f introduced lake trout in these lakes, but other factors, including a ngling, were also important. Closure of lakes to fishing was strongly associated with some successful introductions. MANOVA revealed differe nces in the geophysical and water quality variables, and fish communit y structures among the native, successful, and failed lakes. The lake groups were further distinguished by canonical variate analysis using either geophysical and water quality variables and/or presence-absence of fish species. Lakes were correctly classified to one of the three lake groups with 63-83% accuracy using a cross-validated, chance corre cted, discriminant analysis. Lakes in which new lake trout populations failed to become established were smaller and shallower, had higher t otal dissolved solids, larger littoral areas, smaller hypolimnions, an d richer fish communities, including more lake trout egg and juvenile predators, than lakes that were successfully colonized. Intensity of p redation by indigenous species was a possible cause of failure of intr oduced lake trout to establish self-sustaining populations. Similar fi sh communities in native and failed lakes suggested that invasion and colonization by lake trout was possibly determined by the order of arr ival of colonizing species. This suggested that the present day Great Lakes fish communities, which have experienced a recent net gain in sp ecies, might be resistant to reestablishment of self-sustaining lake t rout stocks.