Aristeus antennatus s or "gamba shrimp" is a resource exploited by bottom trawling at a depth of between 400 and 800 m. This shrimp is the main deep demersal target species off the Western Mediterranean coast. A demographic analysis of A. antennatLls for Catalonia and Valencia is presented in this study. Anual series of length frequencies by sex were analysed over a 6 year period (1984-1989) using Length Cohort Analysis (LCA), which is based on the steady state assumption, and Virtual Population Analysis (VPA). Some yield per recruit (Y/R) analyses were performed in order to get a general view of the status of the stock. Finally, the sensitivity of LCA to demographic parameters K (growth rate) and M (natural mortality) was studied to evaluate the effect of estimation errors. The stocks studied appear not to be far from the steady state and reveal a fairly stable fishery pattern, hence it was possible to use LCA. The Y/R vs effort curves show an exploitation level close to the optimum. Fishing effort changes did not appreciably improve the yield. The shape of these curves, with a right branch decreasing very slightly, makes an exploitation pattern directed at large individuals evident, allowing the small ones to escape, or, perhaps inaccessible to the gear for other reasons.