Spatial correspondence between areas of concentration of Patagonian scallop (Zygochlamys patagonica) and frontal systems in the southwestern Atlantic

Abstract

It has been hypothesized that the geographical location of scallop beds in extensive shelf regions mirrors hydrographic structures (e.g. frontal systems) that favor the retention/concentration of pelagic larvae. Large, discontinuous concentrations of the Patagonian scallop (Zygochlamys patagonica) are known to have occurred recurrently (for more than 30 yr) at certain geographical locations over the extensive Patagonian shelf. These stocks, exploited since 1996, currently support one of the most important scallop fisheries in the world. Here, we investigate whether those aggregations are spatially coincidental with major frontal systems. Several pieces of information were used: historical survey data documenting the geographic distribution of the Patagonian scallop beds, catch and effort data from the commercial fleet, oceanographic data on frontal systems, and remote sensing imagery. We found that large-scale aggregations do match the location of three major and very different frontal systems in the southwestern Atlantic: the Shelf-Break Frontal System, the Northern Patagonia Frontal System, and the Southern Patagonia Frontal System. We describe the three frontal systems and their associated scallops fishing grounds and discuss which processes can contribute to sustaining the productivity of the scallop grounds in each case.

Azadinium poporum from the Argentine Continental Shelf, Southwestern Atlantic, produces azaspiracid-2 and azaspiracid-2 phosphate

“…This is consistent with the fact that occurrence of AZA-2 in shellfish (Brachidontes rodriguezii and Mesodesma mactroides) in Argentina has been recently reported (Turner and Goya, 2015). In this region, natural beds of Zygochlamys patagonica (Patagonian scallop) which are spread along the continental shelf (Bogazzi et al, 2005) are commercially exploited. In addition, wild beds of mollusks from intertidal and subtidal zones, have been traditionally harvested by fishermen and some companies have begun to improve the culture of oysters and mussels along the coast from the South of Buenos Aires, North Patagonian Gulfs and Tierra del Fuego (Medina et al, 2011).…”

Studies on the reproductive dynamics of Pleoticus muelleri (Bate, 1888) (Crustacea, Decapoda, Solenoceridae) of Patagonia, Argentina

“…These environments are characterized by warm temperatures and the development of frontal systems (Boschi, 1989;Bogazzi et al, 2005, De la Garza et al, 2008. These fronts have high primary and secondary productivity that would ensure the best opportunities for larval survival.…”

<i>Mycale (Aegogropila) magellanica</i> (Porifera: Demospongiae) in the southwestern Atlantic Ocean: endobiotic fauna and new distributional information

“…The shelf-break frontal area in the Argentine Sea is one of the most productive ecosystems in the SW Atlantic Ocean (Acha et al 2004, Bogazzi et al 2005 as a consequence of high levels of nutrients (Rivas 2006, Romero et al 2006). This region is dominated by soft-bottoms (sand and mud), like more than 70% of the Argentinean continental shelf (Parker et al 1997).…”