Influence of the Aristeus antennatus larval ecology on simulated dispersal patterns in Nord-Western Mediterranean Sea

Abstract

Connectivity patterns among commercial deep-sea shrimp Aristeus antennatus fishing grounds impact the survival of local populations and shape the efficiency set of management strategies. The ecology of early life stages contributes to connectivity among fishery grounds, with spatial displacements driven by both hydrodynamical features and biological adjustment of the extent and the direction of the drift dispersal. Larval drift simulations were conducted with a biophysical model based on predicted eggs abundance map on the Northwest Mediterranean Sea and a predicted pelagic larval duration. To run the simulations, the lack of knowledge on larval behaviour was substituted by simulated drifts using different buoyancies for eggs and nauplius stages and for different patterns of vertical migration at protozoea and mysis stages. As expected, larval dispersion was higher when located near the surface layers, though it decreased with increasing depth up to 100 m depth. Eggs and nauplius with a buoyancy lower than 1.016 gr.m-3, reached the surface within 3 days from 630 m depth, drifting about 135 km in 20 days. The positive buoyancy and the movement of late larval stages at shallow waters explained the larval connectivity among fishing grounds located at relatively large distances, whereas neutral buoyancies together with migration of larvae toward shallow waters explained the connectivity among nearby fishing grounds