Abstract

Seasonal movements of red grouper Epinephelus morio over the north continental shelf of the Yucatan Peninsula are a very sensitive consideration in fishery management because this species is overfished. An evaluation of the patterns of population movement is conducted using a spatial-dynamic model. Rates of flow of individuals between adjacent zones are estimated, considering the structure of the population (juveniles, pre-adults, and adults). The model used information of catch per unit effort and length frequency data of the Mexican mid-size fleet during 1973 which was the period of the highest historical catch. A variable, catchability-with-size, time, and zone, as well as natural mortality-at-age are considered. Results show seasonal patterns of movement differentiated by developmental stage. Movements of concentrations of adult fish occurred between winter and spring in the central and eastern parts of the north continental shelf of Yucatan in depths from 35 to 60 m; whereas pre-adults and juveniles moved in the opposite direction towards shallow zones. Population moves to the western zone of the continental shelf in spring-summer. Adults had higher flow rates than juveniles; nevertheless, there were large movements of juveniles towards the north of the continental shelf and in front of the Dzilam de Bravo and Rio Lagartos zones. Results show the importance of this information to guide fishery management polices, including exploration of marine protected areas or fishing closures to allow depleted stock to recover.

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