Genetic evidence of two stocks of the whitemouth croaker Micropogonias furnieri in the Río de la Plata and oceanic front in Uruguay

Analysis of the mitochondrial DNA control region resolved two stocks of whitemouth croaker Micropogonias furnieri in Uruguayan waters, one in the Río de la Plata and the other on the Uruguayan shelf. The whitemouth croaker is the most important coastal fishery resource along the coast and has the greatest commercial importance in the Río de la Plata and its oceanic front. The number of pair-wise differences (pi) and haplotype diversity (h) showed significant differences between the two regions. Frequencies of mtDNA haplotypes did not differ between Río de la Plata from Bahia Blanca M. furnieri. Samples from the oceanic front showed greater genetic variability and a larger effective number of females that were an order of magnitude larger than that in Río de la Plata. Mismatch distributions showed evidence of a recent population expansion in the oceanic region, beginning c. 40,000 b.p. The presence of two stocks of the M. furnieri in the study area should be considered in the management of this species' fishery.