Effect of global warming on Mediterranean demersal communities: the case of Parapenaeus longirostris along the western coasts of Italy as indicator species for global warming in Mediterranean Sea

The effect of temperature increase on the stock of the deep-sea pink shrimp was analysed along the western coasts of Italy. This crustacean is currently one of the most important commercial species of the trawl fisheries in the Mediterranean Sea. Landings of the species in the North Tyrrhenian-Ligurian Sea have grown consistently during the last years following a rapid increase in the stock size. Since the deepsea pink shrimp stock is exploited on the same fishing ground of other heavily overexploited stocks in a full mixed and poorly selective fishery, its condition seems to be largely independent of the current fishing exploitation pattern suggesting a positive role of the ongoing environmental change on the dynamic of the stock. To test this hypothesis we investigated the effect of sea surface temperature (SST) on density and distribution of P. longirostris in the North Tyrrhenian-Ligurian Sea by means of general additive models (GAMs). Two different models were developed for the whole stock and recruits (CL<20 mm) using time series of Medits trawl survey density indices (n km-2) covering the period 1995-2010. Predictors included, geographical coordinates, quarterly averaged minimum SST, sampling depth and year. Spawners density was included into the GAM model for recruits. Although the GAMs output return interesting results, we are currently implementing Bayesian models to improve the understanding of the interaction between the deep-sea pink shrimp and temperatures.