Genetic Stock Structure of Juvenile Channel Ictalurus punctatus and Blue Ictalurus furcatus Catfish in a Large Unimpounded River

For sportfishes in large rivers, little information is currently available regarding their genetic stock structure which can be vital to continuing the sustainable exploitation of these fisheries. In Illinois, Channel and Blue Catfish are some of the most important fisheries in large rivers; therefore, understanding and assessing their genetic integrity should be of utmost importance for managers. Sixteen microsatellite loci were utilized to assess the genetic structure of juvenile Channel (n = 30) and Blue (n = 11) Catfish from two sites approximately 290 river km apart on the Wabash River. Both species from both sites showed high observed heterozygosity (H_O > 0.90), low inbreeding (F_IS < -0.18), and low mean pairwise relatedness (MPR < 0.07). Additionally, there is significant genetic variation for both Channel (F_ST = 0.017, P = 0.003) and Blue (F_ST = 0.033, P = 0.007) Catfish between the two sites which indicates there are isolated populations. Although isolated populations are present, they all have high heterozygosity, low inbreeding, and low relatedness which is ideal for commercially exploited fishes. Additionally, we plan to test other sites between the two sites already tested, and upstream of the northern most site.