University of Miami Rosenstiel School of Marine and Atmospheric Science
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Grouper Information

All Groupers fall under the family Serranidae, and the order Perciformes. They’re categorized in either of two genera, Epinephelus or Mycteroperca. Groupers are often recognized for their large mouth and heavy body. Their colors are usually dull tones of greens and browns, but there are a few with some more boldly colored bright patterns. The Nassau Grouper can even change its colors. Some species will also grow to immense sizes, with the Goliath Grouper having been recorded up to 8.2 feet in length and weighing as much as 1000 pounds. They are a carnivorous species that feed on fish, squid, and crustaceans. Some species have a suction powerful enough to engulf small prey close by.

Groupers are actually protogynous hermaphrodites, meaning they start their lives as females and later change their gender to male as they mature. The advantage to this strategy is to ensure there are enough females around to spawn eggs and keep the population numbers up. The males can breed with multiple females in the meantime. Groupers have a longer lifespan than some fish and grow very slowly, but spawn a large number of eggs each year. The Gulf Grouper can live up to 48 years and spend six years of its life as a female before changing genders. Unfortunately, the Grouper’s large size and slow growth are part of the reason why many species are listed as either vulnerable or threatened according to the IUCN. The Gulf Grouper and Goliath Grouper are both on the endangered species list.

Groupers are a prime food and sport fish and suffer greatly both from direct harvest and by-catch by humans. It’s very easy for fisherman to harvest a large number of groupers at once because they know where and when they will aggregate. Gulf Groupers, for example, congregate in large numbers when they’re looking to reproduce, usually in known reef and seamount locations during a full moon in May. Fishermen are targeting the older male Groupers in these groups. Even when fishermen aren’t looking to collect Groupers though, their large size makes these fish susceptible to getting trapped in nets by accident as by-catch. All of this causes the sex ratio to become unbalanced in the population, usually with more females than males. There are fewer pairs to mate, and likely a lack of genetic diversity within a population as a result.

There are several conservation measures put in place to protect Groupers. Harvest of the Nassau Grouper is prohibited in the United States, and any for any other Grouper species, fishermen must adhere to certain bag limits and size restrictions. While these practices as beneficial to the species, it should be noted that Groupers also suffer from degradation and loss of reef habitats, as well as any negative climate change effects on reef ecosystems. To properly sustain Grouper populations, humans need to keep an open mind as to both the direct and indirect factors that make it difficult for a population to rebuild.