Identifying Black Grouper (Mycteroperca bonaci) Spawning Aggregations off Belize: Conservation and Management

Black grouper (Mycteroperca bonaci) is a protogynous serranid that spawns in late winter (peak in February - March). In Belize, black grouper form many small aggregations that move into deep water off of the reef face as spawning approaches. Spawning occurs in pairs that rush upward in the water column at dusk, spawn, and then rejoin the aggregation. During spawning, males exhibit a white-head phase, and spawn with dark-phase females. Blotched and light phases are also exhibited at all times of the year. Spawning occurs from the full moon to a few days after the new moon, and occurs along a variety of reef formations, including elbows, promontories, and linear shelf-edge reef. The formation of many small aggregations, rather than a few large ones, a slightly more protracted spawning period, and the feeding and diver avoidance behavior of black grouper has made it less vulnerable than some other groupers to fisheries in Belize, but it has been overfished in other parts of its range, and additional protection of spawning sites and habitats of juveniles is needed.