Reproductive Biology of Three Important Threatened/Near-Threatened Groupers (Plectropomus leopardus, Epinephelus polyphekadion and Plectropomus areolatus) in Eastern Indonesia and Implications for Management

SIMPLE SUMMARY: Indonesia needs basic data on the reproductive dynamics of economically important fishery species, including groupers, in order to support sustainable fisheries management. Data from the histological examination of grouper gonad samples were combined with data from: participatory mapping and interviews with fishermen, monitoring data from known spawning aggregation sites, and analyzed descriptively to provide basic data on the size at first maturity and seasonal reproductive patterns of three economically important groupers. We suggest management measures including size limits, temporal spatial closures, and a trading ban during the peak spawning season (November–December). ABSTRACT: The three grouper species most heavily fished for the live reef fish trade (LRFT) in Indonesia are Plectopomus leopardus (greatest catch volume), and two species classified as Vulnerable on the International Union for Conservation of Nature (IUCN) Red List: Plectropomus areolatus and Epinephelus polyphekadion. Understanding the reproductive biology of these fishes is essential for sustainable management, but relevant data are limited. This study aimed to determine reproductive dynamics, so as to inform management measures to maintain the reproductive capacity of these groupers. Grouper gonad samples collected from fish caught for the LRFT were analyzed histologically. Data were also collected from participatory mapping and interviews with fishermen, and underwater monitoring of three known spawning aggregation sites in the Wakatobi National Park, Eastern Indonesia. Based on observed gonad development, the respective lengths and weights at first maturity were: 37.7 cm and 759 g (P. leopardus); 36.65 cm and 771.2 g (P. areolatus); 36.95 cm and 889.9 g (E. polyphekadion). The mean weight of the groupers market-based sampled was higher than the size at first sexual maturity. Sex transition was observed in P. leopardus; sex reversal was not observed in E. polyphekadion, and the sex pattern of P. areolatus was unresolved. Based on the fisher surveys and spawning aggregation monitoring, spawning occurs around the new moon from September to April, with reproductive peaks in November and December. Fisheries management measures that are suggested to sustain grouper stocks include enforcing appropriate size limits, temporal spatial closures (spawning aggregation sites), and a trading ban during the peak spawning season (November–December).