Reproductive characteristics of the orbiculate cardinalfish Sphaeramia orbicularis in the Chuuk Lagoon, Micronesia

Abstract

Detailed knowledge of the reproductive characteristics of fish in tropical areas is currently lacking. We have performed a histological study of the reproductive aspects of , a tropical fish found on the Weno Islands of the Chuuk Lagoon, Micronesia, and further estimated the gonadosomatic indices (GSI) of this fish. The sex ratio was approximately 1:1. The standard length of males and females at 50% maturity was 49.0 and 46.9 mm, respectively. Histological observation of ovaries and testes revealed that the fish exhibits multiple spawner characteristics, including coexistence of primary yolk stages, migratory nucleus or mature stages, and asynchronism of the spermatogenesis process. Monthly variations in the GSI and gonadal maturity stages demonstrated that reproductive activity occurs throughout the year. The findings in this study provide important information on the spawning activity and season of in Micronesia.