Temporal and spatial connectivity and divergence among river and reef spawning groups of walleye: Patterns across 15 years

Genetic connectivity and divergence patterns among walleye spawning groups are investigated for temporal and spatial stability from 1995-2010 river and reef Lake Erie sites. Results are compared with those from our previous study using 9 microsatellite loci that tested variation among 800 spawning walleye from 11 Lake Erie river and reef sites in 2003, discerning divergence among some groups and greater connectivity among those from the Sandusky and Maumee Rivers, and Van Buren Bay reef. This new study analyzed variation within and among >800 walleye spawning at those three sites from 1995, 1998, 2003, 2005, 2007, 2008, and 2010 using 15 loci, to assess whether this pattern of connectivity varied among years and cohorts. Relationships were tested using pairwise FST analogs and contingency tests, AMOVA partitioning, trees, and Bayesian assignment tests. Results revealed general temporal genetic consistency among walleye spawning within sites, with greater genetic divergence among the 3 runs in some years and less in others. These results indicate that a single year “snapshot” of walleye spawning groups may not adequately characterize their genetic connectivity and divergence patterns, illustrating the importance of understanding temporal stock structure to assist fisheries management.