AN EVALUATION OF LAKE TROUT REPRODUCTIVE HABITAT ON CLAY BANKS REEF, NORTHWESTERN LAKE-MICHIGAN

The extinction of the native populations of lake trout (Salvelinus nam aycush) in Lake Michigan in about 1956 has been followed by a decades- long attempt to reestablish self-sustaining populations of this valuab le species in habitats it formerly occupied throughout the lake. One o f the most recent management strategies designed to facilitate recover y was to make a primary management objective the establishment of sanc tuaries where stocked lake trout could be protected and self-sustainin g populations reestablished. In the present study we employed habitat survey and mapping techniques, field and laboratory bioassays, egg tra ps, sediment traps, and gill nets to examine the potential for success ful natural reproduction by stocked lake trout on Clay Banks Reef in t he Door-Kewaunee sanctuary in Wisconsin waters of Lake Michigan. Our s tudy revealed (1) there was suitable habitat on the reef to support th e production of viable fry, (2) spawner abundance on the reef was the highest recorded in the Great Lakes, and (3) eggs taken from spawners on the reef and held on the reef in Plexiglas incubators hatched and p roduced fry that survived through swim-up. We conclude that Clay Banks Reef has the potential to support successful natural reproduction by stocked lake trout.