Bivalve phenotypic stocks of the San José gulf, Patagonian Argentina. Using geometric morphometrics for their determination.

FEDERICO MARQUEZ; SILVINA VAN DER MOLEN

Dalian

Congreso; BIT?s 3rd Annual World Congress of Aquaculture and Fisheries-2014 (WCAF); 2014

Dalian Ocean University

Morphologic variation approach has been often used for phenotypic stock differentiation at inter and intra-specific level. Moreover, the use of Geometric Morphometric is an efficient and powerful technique to the assessment of fishery stocks in mollusks. The bivalves Aulacomya atra, Aequipecten tehuelchus, Ensis macha and Ameghinomya antiqua are the principal artisanal fishery resources of the San José gulf. As many marine invertebrates, most of bivalves in San José gulf are structured as metapopulations: groups of populations of sedentary adult individuals linked by a dispersing planktonic larval stage. Furthermore, these populations are under different environmental conditions: nutrient availability, type of substrates, predation, and oceanographic features. The spatial structure of benthic stocks has significant implications either to the understanding of the population dynamic, as to the design of management strategies. The aim of the present study was to determine the occurrence of phenotypic stocks of the four bivalve mollusks applying geometric morphometric techniques. We compared the most used fishing grounds of the San José by artisanal fishermen. Our results show that landmarks morphometric technique is highly effective for the discrimination of intraspecific fishing grounds based on shell shape variation. These bivalve fisheries from San José Gulf are regulated through a system of prohibition of capture as a result of a phenomenon called red tide: recurrent episodes of blooms of harmful marine microalgae and heterotrophic dinoflagellates, and/or overfishing. These phenomenons are present in specific zones of the gulf, but not in the whole Gulf at the same time. Thus, data on the provenance of the fished individuals would enable better planning of preventing measures or management actions in the different fishing grounds. We postulated that the implementation of geometric morphometric techniques would be appropriate for identification and management of the bivalve fisheries stocks in the north Patagonian gulfs.