Monitoring annual changes in the squat lobster Munida gregaria swarms of San Jorge Gulf, Southern Patagonia

MARIANO J. DIEZ; ARIEL G. CABREIRA; ADRIAN MADIROLAS; GUSTAVO ALVAREZ COLOMBO; GUSTAVO A. LOVRICH

Nantes

Simposio; ICES Symposium of Marine Ecosystem Acoustics; 2015

ICES

The squat lobster Munida gregaria is a benthic crustacean that inhabits in the Argentine Sea (SWAO). Particularly, in waters of San Jorge Gulf, the pelagic aggregations of this species increased greatly in number and density during recent years. Regular acousticsurveys conducted by INIDEP (2008-2012) detected the first pelagic swarms of the species, located mostly at the south-eastern end of the gulf. These swarms are characterized by mid water scattering layers whose density and spatial dimensions are variable. In some cases, the pelagic swarms extend horizontally for several nautical miles and are located at varying depths in the water column, from 20 m depth to the bottom. The analysis of the acoustic sections from this survey series revealed annual changes in the aggregations patterns as well as in the proportion of the water column being occupied by the species, with a peak value recorded in 2010.