Since the 1980’s, spotted seatrout (Cynoscion nebulosus) along the Texas coast, have been managed by the Texas Parks and Wildlife Department (TPWD).  This species is an important recreational fishery in Texas that is stocked by TPWD only into the bays from which the broodstock were captured.  Because previous studies using genetics markers, morphological and physiological variation, and tagging as measures of stock structure are discordant, we examined amounts and distribution of variation in the mitochondrial gene ND4 to investigate genetic structure to assess the importance of current TPWD stocking practices.  We extracted DNA from ca. 24 individuals from each of nine bay systems (Upper and Lower Laguna Madre, Baffin Bay, Corpus Christi Bay, San Antonio Bay, Aransas Bay, Matagorda Bay, and Galveston Bay in Texas, and Mobile Bay, Alabama).  We designed primers to capture ND4 from spotted seatrout sequences in GenBank and used PCR to copy this region of the mitochondrial genome.  The resulting products were sequenced on a CEQ 8000.  Genetic structure was examined by Analysis of Molecular Variance (AMOVA) using Arlequin 3.1 with bays grouped into three regions: (1) Alabama alone, (2) upper Texas coast, and (3) lower Texas coast for this analysis.

Results/Conclusions

Of the 1018 nucleotide sites we examined, 54 were polymorphic and produced 56 different haplotypes.  The AMOVA revealed that approximately 5% of the variation among our samples was due variation among our three regions, but this was not statistically different from 0 (P = 0.09).  However, the variation among populations within groups was small but statistically significant (7%, P = 0.006).  Most of the variation within populations (88%, P = 0.0001).  These data indicate weak, but significant genetic structure among spotted seatrout in bays of the western Gulf of Mexico.  Thus, fish from different bay systems may represent different stocks.  Thus, TPWD’s current stocking practices should be continued.