The reproductive biology of intertidal klipfish (Perciformes: Clinidae) in South Africa
The reproductive biology of six species of viviparous intertidal clinid fish was investigated. Fish were collected monthly from intertidal rock pools between May 1992 and May 1993. Sex ratios varied between 36% female in Clinus acuminatus to 53% female in C. superciliosus, although this was only significantly different from a 50:50 ratio in C. acuminatus (χ2; p<0,05). Size at maturity was greater in females than males of all species and was related to maximium attainable size. Gonad mass varied between 2,6% and 11,6% body mass in males, in males, and reached a maximum of 27,9% in females of C. agilis. In five of the species studied, increases in relative gonad mass of males from March to August were followed by increases in gonad mass of females between September and February, suggesting a gestation period of 4-6 months. Only C. superciliosus indicated no seasonal trends in gonad development. Juveniles recruited to intertidal rock pools in summer at a total length of between 20 and 25 mm. Up to nine broods of eggs and embryos of different ages were found in the gonads at one time, although there was no relationship between the number of broods and fish size. The total number of reproductive elements (eggs and embryos), however, increased with fish mass in all species. Reproductive potential, calculated as the mean number of broods per mature female multiplied by the mean number of reproductive elements per female, varied from a high of 2843 in C. acuminatus to 237 in Muraenoclinus dorsalis.