Abstract

Black grouper (Mycteroperca bonaci) are an historically important species in Bermuda’s reef fishery but until recently little was known of their biology. They were taken in large numbers by fish pots up until the 1970s but reported landings declined dramatically from 1975 - 1981 before partially recovering. Following the Fish Pot Ban of 1990, only hook-and-line fishing was permitted and landings remained relatively low. A gear innovation (trolling) in 2001 increased catchability and landings rose substantially. The need for detailed biological information for management of this revitalized fishery prompted the current study. Black grouper were found to be protogynous hermaphrodites transforming from female to male in the size range 105 – 115 cm FL (22 – 29 kg). Transverse sections of polished otoliths (sagittae) were used to estimate age. Black grouper are relatively slow-growing and long-lived. The oldest specimen was 33 years old, and the age at sexual transition was approximately 11 - 14 years. This information is pivotal in understanding the population structure in order to enact appropriate management measures. As black groupers form spawning aggregations in Bermuda, these aggregation sites are seasonally closed to all fishing to protect the spawning population.

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