ASSESSING THE GENETIC INFLUENCES OF RED DRUM <i>Sciaenops ocellatus</i> STOCK ENHANCEMENT IN SOUTH CAROLINA.
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<p>The South Carolina Department of Natural Resources began a stock enhancement research program for red drum <i>Sciaenops ocellatus</i> to explore stock enhancement as a potential management tool in addition to restrictive fishing regulations by augmenting the abundance of juveniles available for recreational harvest in SC estuaries. Stock enhancement has been historically criticized for its potential to decrease genetic diversity and increase levels of inbreeding in the wild population. Between 1999 and 2011, approximately six million juvenile red drum and 100 million larvae were stocked into the Charleston Harbor estuary. Standardized sampling of sub-adults within the estuary (total N=3,361), as well as the spatially separate offshore adult population (total N=796) found proportions of stocked fish as high as 49.6% within a single year-class and up to 12% within the local spawning population, respectively. This study evaluated the genetic influences of stock enhancement on the wild adult population by calculating a suite of genetic diversity metrics using microsatellite loci, and then utilized these metrics to validate an individual-based model (IBM) to forecast the genetic influences of future stocking strategies in SC. No statistically significant differences were found among year-classes (sub-adult samples) or collection years (adult samples) for any genetic diversity metric, suggesting that responsible stocking of red drum as small juveniles has not altered the genetic diversity among wild adults in SC. Simulations monitored changes in genetic diversity under several stocking scenarios, which included: the effective number of breeders in the hatchery (2, 6, and 10), the contribution of stocked fish to each year-class in the wild (30, 60 and 90%), and the census size of the wild adult population (500, 5,000 and 50,000). The IBM accurately simulated empirical estimates of genetic diversity from 1999 to 2011, and could therefore inform responsible stocking strategies for continued red drum stocking efforts in South Carolina.</p>