MORTALITY AND STOCK ASSESSMENT OF THE BROWN SHRIMP, PENAEUS-AZTECUS (CRUSTACEA, PENAEIDAE), IN THE NORTHWEST GULF-OF-MEXICO

Fishing mortality of the brown shrimp (Penaeus aztecus) was estimated off Tamaulipas (northwest Gulf of Mexico). Monthly age structure and f ishing effort data for the 1974-1980 period, and cohort analysis by th e virtual population analysis (VPA) technique were used. Catchability estimates indicate higher values for the first maturity age (six month s old), fishing mortality increases with age, with an asymptotic tende ncy after 8-9 moths old, F=0.5 (1/year). Variance of F also increases with age. Population size has strong interannual variations because of recruitment, though the seasonal recruitment pattern was similar duri ng the period. The monthly cohort tendency suggests a stable situation for the stock during this period.