GENETIC AND TAGGING EVIDENCE FOR MOVEMENT OF WALLEYES BETWEEN LAKE ERIE AND LAKE ST-CLAIR

Walleyes (Stizostedion vitreum vitreum) from Lake Erie differed in all ele frequencies from walleyes in Lake St. Clair (N = 1,680; 25 loci); however, only slight differences were found among walleyes from differ ent spawning sites in each lake. Analyses of allele frequency data fro m samples of nonspawning walleyes taken in Lake St. Clair provided con ditional maximum likelihood estimates that 86% of these walleyes were from Lake St. Clair and 14% from Lake Erie (SD = 19.7%) in 1983 and th at 63% were from Lake St. Clair and 37% were from Lake Erie (SD = 20.0 %) in 1984. About 30% of 1,159 recoveries of walleyes tagged in Lake E rie were taken from the Detroit River northward to southern Lake Huron , thus demonstrating extensive mixing of stocks from Lake Erie and Lak e St. Clair. Additionally, tags recovered from the upper half of the S t. Clair River provided an estimate of mixed stock composition of 76% Lake St. Clair fish and 24% Lake Erie fish. Analyses of tags returned during successive spawning seasons showed that walleyes strongly tende d to return to suspected natal spawning areas. The tagging data thus c orroborate the genetic evidence that walleye stocks from Lake St. Clai r and Lake Erie are different, and that large numbers of Lake Erie wal leyes enter Lake St. Clair during nonspawning seasons and return to th eir Lake Erie spawning sites each year. Western Lake Erie and Lake St. Clair walleyes should be considered as separate stocks for management purposes.