Genetic Variation and Relatedness of Juvenile Red Snapper Sampled from Shrimp Trawls in the Northern Gulf of Mexico

Abstract

We studied genetic variation and genetic relatedness among young-of-the-year (age-0) Gulf of Mexico red snapper Lutjanus campechanus sampled as bycatch in two separate shrimp trawl tows offshore of Galveston, Texas, and in a reference (control) group composed of multiple samples from within the same geographic area. Allelic and haplotypic variation was assayed at 11 microsatellite loci and mitochondrial DNA, respectively. Samples taken as bycatch from shrimp trawls did not differ from the reference group in allele richness, gene diversity, or allele frequency, indicating that most of the genetic variability within the cohort studied was attributable to fish sampled during single, localized tows of the shrimp trawler. Estimates of the variance of pairwise relatedness in the reference sample and in one of the bycatch samples were zero, whereas in the other bycatch sample the variance estimate was 0.001 (P = 0.1). A positive variance suggests that this sample contained individuals that were more closely related genetically than would be expected by chance alone. Because the relatedness estimators are sensitive to sample size, the number of loci, and allele distributions, further studies employing larger sample sizes and additional loci are warranted.