California Sea Grant College Program

Since the 1980s total landings for protogynous California sheephead have doubled and their abundances have declined. This study used histology to determine sexual type (immature, female, transitional or male) of sheephead collected from nine southern California populations. Fecundity was estimated for all active females and reproductive potential was assessed for each population. In five populations sheephead were undergoing sexual transition (i.e. reproductively non-functional) during the summer breeding season. The proportions of the populations in transition ranged from 2.4% at San Nicolas to 25% at Santa Catalina Island. Northwestern populations had greater reproductive potential than southeastern populations and the greatest reproductive potential was observed in the most remote population (San Nicolas Island) and at two marine protected areas (MPA). Multivariate analysis of biological variables and explanatory variables found that sea surface temperature best explains trends observed in the biological data; however, remote locations and MPA may enhance reproductive potential of sheephead.