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 fishing effort data for the 1974-1980 period, and cohort analysis by the virtual population analysis (VPA) technique were used. Catchability estimates indicate higher values for the first maturity age (six months old), fishing mortality increases with age, with an asymptotic tendency 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 during the period. The monthly cohort tendency suggests a stable situation for the stock during this period.