RANGE DETERMINATION OF (Cynoscion arenarius) AND CHARACTERIZATION OF (Cynoscion spp.) HYBRIDIZATION IN NEARSHORE HABITATS ALONG THE SOUTHEASTERN U.S. ATLANTIC COAST WITH IMPLICATIONS FOR MANAGEMENT OF (Cynoscion regalis)
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Jamison, Margaret May
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Abstract
Weakfish, Cynoscion regalis, is a priority species, regulated by the Atlantic States Marine Fisheries Commission (ASMFC), and comprises an important recreational and commercial fishery along the U.S. Atlantic coast. A potential range expansion of a closely related Gulf species, sand seatrout (C. arenarius), along the U.S. Atlantic coast as well as the occurrence of Cynoscion spp. hybrids are causing difficulties in morphological field identification, which is a critical foundation of stock assessment. Genetic markers were optimized to genetically identify all Cynoscion spp. and their hybrids found in the Atlantic. The resulting genetic tool was used to verify past and current collections ofC. regalis along the southeastern U.S. Atlantic coast and to preliminarily investigate the extent of C. arenarius possible range expansion as well as the degree of hybridization among Cynoscion spp. Initial results indicate 93.3% of C. regalis morphological identifications are accurate, but hybridization is occurring with two out of the three Cynoscion species found in the Atlantic. Preliminary work supports the establishment of a C. arenarius range along the U.S. Atlantic coast north to southern Georgia. However, samples from the previous work focused on problematic specimens and did not represent a random sample of the fish community. Samples randomly selected the by SEAMAP-SA 2013 and the SCDNR Inshore Fisheries spring collections (n= 927) were analyzed to further investigate the range expansion of C. arenarius and degree of hybridization of Cynoscion spp., particularly with C. regalis. Results provide evidence of a bimodal, dispersal-dependent hybrid zone occurring in Florida. These findings provide valuable information regarding C. arenarius distribution, the hybrid zone dynamics and their potential impact on C. regalis stocks.