The effects of temperature and daylength on the reproductive physiology of the viviparous seaperch, Cymatogaster aggregata Gibbons

Abstract

The effects of temperature and photoperiod on the reproductive physiology of Cymatogaster aggregata are examined experimentally and related to the conditions in nature. In males an increasing or long photoperiod in late winter, spring, or early summer results in spermatogenesis, development of secondary sex structures, and reproductive behavior; warm temperatures markedly enhance these processes. The cold temperature and short photoperiod of the winter months promote testicular restitution and growth of spermatogonia.In females, oocyte formation is enhanced by the warm temperature (and perhaps decreasing photoperiod) of late summer and eariy autumn, while oocyte maturation is fostered by the cold temperatures of early winter. Early gestation requires a cold temperature but during late pregnancy a warm temperature will enhance growth of embryos.