Diversity of sexual strategies of fish species caught by bottom trawl off the western Iberian Peninsula

Abstract

Samples of boarfish Capros aper, small red scorpionfish Scorpaena notata and comber Serranus cabrilla were collected from monthly by-catch samples on board commercial trawlers off the western coast of Portugal. A histological approach was undertaken to study each species’ reproductive strategy and annual sexual cycle. Temporal variations of the gonadosomatic index and of two condition indices (hepatosomatic and Fulton's K) were also analysed. Results showed that C. aper and S. notata are gonochoristic whilst S. cabrilla is a simultaneous hermaphrodite. Fertilization is external and development of secondary growth follicles is asynchronous in the three species. Mass atresia characterized the end of the spawning season in S. notata and S. cabrilla. In C. aper a high prevalence of atresia was observed throughout the year and was not attributed to regressing or regenerating phases or skip spawning events. The main spawning season of the three species was in the summer and it is suggested that spawning is related to upwelling. During the summer, the spawning interval was 1.09, 1.23 and 1.84 days for S. cabrilla, S. notata and C.aper, respectively. The results of this study indicate potential plasticity and environmental adaptation of sexual strategies.