Reproductive cycle of female yellow snapper Lutjanus argentiventris (Pisces, Actinopterygii, Lutjanidae) in the SW Gulf of California: gonadic stages, spawning seasonality and length at sexual maturity

The yellow snapper (Lutjanus argentiventris) in the SW Gulf of California is being heavily fished and little information exists on status of this exploited population. From August 2001 to May 2003, 440 specimens in the size range of 10.8-59 cm were collected from four fishing areas: Huizache-Caimanero, Mazatlan, Marmol and Santa Maria la Reforma in the SW Gulf of California. Specimens were collected from fishermen and obtained by sampling with gill nets, hook and line and spear gun fishing. Gonadal stages, spawning season and length-at-first maturity were estimated for female yellow snapper through histological analyses and relative gonadosomatic (GSI) and hepatosomatic (HSI) indexes. Six gonadal stages were identified and gonadal development was asynchronous. Gonads in advanced stage VI of vitellogenesis occurred during summer and winter together with the highest values of the GSI and HSI, indicating that spawning occurred during these seasons. Mean maturity length was determined to be 32.6 cm total length. The yellow snapper population was being adversely affected considering that the species was exploited throughout the year, including the reproductive seasons, and that organisms as small as 10 cm were found in fishermen's catches and at fish markets. Minimum capture sizes of 33 cm and a closed season during the reproductive periods of summer and winter are suggested as measures to reduce the adverse affects of this exploitation.