Population Connectivity and Maintenance of Genetic Structure in Yellow Perch Populations in Western Lake Erie and the Lake St. Clair-Detroit River Corridor

Ability to quantify connectivity among local spawning populations and their relative contribution of recruits to the fishable population is critical to fisheries management in marine and freshwater ecosystems.  We explored such stock structure in yellow perch (Perca flavescens) residing in the Lake St. Clair – Detroit River corridor (SC-DRc) and western Lake Erie, using larval otolith microchemistry (strontium, barium) and genetics (9 microsatellite loci) as natural tags to potentially discriminate among these stocks and then identify the contribution of juvenile recruits during 2006-2007.  Our results show that the SC-DRc and Lake Erie are “connected” via larval dispersal with a measurable level of SC-DRc larvae recruiting to the juvenile stage in western Lake Erie.  Interestingly, however, significant stable genetic structure existed between “stocks” (F_ST = 0.014 and 0.018 between DR-ERIE in 2006 and 2007, respectively).  This maintenance of genetic diversity between the SC-DRc and Lake Erie appears due to 1) low export of SC-DRc larvae relative to in-lake larval production and 2) slow growth rates (first 10 d of life, as recorded in otoliths) in SC-DRc larvae, which likely enhances growth-dependent mortality via predation. We discuss these mechanisms more fully and the implications of these findings to Great Lakes fisheries management.