Genetic Evaluation of Spring Catch-and-Immediate Release Largemouth Bass Fishing Regulations

In 2006 Michigan black bass fishing regulations were changed to include a spring catch-and-immediate release(CIR)  season prior to a traditional possession season.  During this time spawning male bass are vulnerable to the negative effects of angling.  While the negative effects of angling on individual bass nests have been well documented, effects on population recruitment remain uncertain.   Our research is part of an evaluation of potential population level effects of spring fishing on black bass.  We used nest monitoring (2 lakes, 2009-2010, 32-132 nests per lake-year), experimental angling (1 lake 2010), young of year surveys and genetic techniques to assess the effects of spring fishing on bass recruitment.   Young of year bass were assigned to their nest of origin based on pedigree reconstruction using multi-locus genotypes to determine the proportional contribution of each nest to recruitment.  Results revealed that nests experimentally angled (CIR) produced five times fewer young of year bass relative to control nests.  Additionally, we are comparing between lakes of different angling pressure to determine if lake wide angling levels affect the genetic composition of young of year populations.  Furthermore, our research has provided insight into black bass reproductive ecology by revealing the prevalence of polygamy, polyandry and repeat spawning between years, all of which influence effective population size.  The results of our study demonstrated the variety of largemouth bass mating systems, and that experimental angling reduced the contribution of nests to recruitment.  It is important that managers consider these factors when regulating bass fisheries because of the potential selective force that angling might exert on bass fisheries.