Red grouper (Epinephelus morio)

French: Mérou Rouge
Spanish: Mero Americano, Mero Guasa
GenusEpinephelus (1)
SizeMaximum head-body length: 125 cm (2)
Maximum weight: 23 kg (2)

Classified as Near Threatened (NT) on the IUCN Red List (1).

A large bodied, robust fish, the red grouper is a dominant predator in the coral reefs of the western Atlantic Ocean. The red grouper is similar in appearance to many other groupers, but distinguished by a larger, spiny dorsal fin, comparatively longer pectoral fins and shorter pelvic fins. As the common name suggests, it is a dark reddish brown colour, fading into pink on the undersides, with a scattering of white spots and blotches. Conspicuous eyes sit behind a large, gaping jaw with an array of strong, slender teeth, used to rasp at prey (2).

Restricted to just the western Atlantic Ocean, the red grouper is found from the North Carolina coast in the United States, through the Caribbean Sea and the Gulf of Mexico, to southern Brazil (3).

When mature, the red grouper is most abundant at depths of 50 to 300 metres, in waters with a sandy or muddy bottom. However, habitat selection in the red grouper changes with age, and the smallest juveniles tend to be found in shallow seagrass beds and inshore reefs. Intermediate aged fish are commonly found under crevices and ledges in rocky coral reefs, between a depth of 5 and 25 metres (1) (3).  

Displaying the remarkable ability to change its sex, the red grouper is a protogynous hermaphrodite, starting its life as a female, and later changing to a male. Females reach sexual maturity after four to six years of age, before participating in spawning events between January and April, with females and males simultaneously releasing millions of eggs and sperm into the water. Around 30 hours after fertilisation, the eggs hatch and the larval fish begin life as part of the zooplankton, floating passively in the ocean’s currents. After a further 35 to 50 days of growth, the benthic young fish will start to feed on small, ground-dwelling crustaceans amongst seagrasses (4). Heavily predated by larger fish, it is only once they reach a moderate size that the young groupers move away from the shelter of the grasses towards deeper, more dangerous waters. If the red groupers successfully avoid predation they may change to males after 7 to 14 years, and possibly live to a staggering 30 years of age (2) (5).   

Growing over a metre in length, these dominating marine predators are high-up the food chain. Opportunistically preying upon a variety of crabs, shrimps, octopuses and fish, such as snappers and parrotfish, the red grouper has a significant influence on the abundance of other reef-dwelling species and the overall health of the fragile coral reef ecosystem (2) (6). Juvenile red groupers are important prey for other predatory fish, such as mackerels and jacks (6). 

A victim of ongoing unsustainable fishing, the red grouper has undergone a dramatic decline. Worth $164.8 million between 1987 and 2001, the red grouper is one of the most important commercial fishes in the United States. It is also the most commonly fished species on Isla de Margarita, Venezuela, and makes up to 90 percent of the total catch on the Yucutan Peninsula, Mexico (3). However, this intensive fishing has been unsustainable, with fisheries in the Gulf of Mexico up to 1985 estimated to have taken 45 percent more fish than deemed sustainable (7). Consequently, total catch in US waters has dropped 50 percent in the last 55 years, while landings in Brazil declined by 89 percent between 1985 and 1994. Although not currently listed as threatened on the IUCN Red List of Threatened Species, ongoing declines and continuing fishing pressures, which are often unregulated, suggest that this species is likely to qualify for a threatened status in the near future (1).      

In the face of such intense fishing pressure, the implementation of conservation measures is essential to maintain commercial stocks of the red grouper, and prevent further population declines. Consequently, the US government has introduced strict regulations, prohibiting the catch of juvenile fish under 18 inches in length. Similarly, in Mexico there is a minimum catch size of 12 inches, and in Cuba, an annual maximum quota of 1,200 metric tons. Furthermore, in the Gulf of Mexico a no-fishing period runs through January and February each year. However, it remains unclear if these measures are succeeding in reversing the plight of this increasingly rare fish (1).

For more information on the red grouper, see:

For more information on the conservation of coral reefs, see:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:

  1. IUCN Red List (February, 2010)
  2. The Florida Museum of Natural History (February, 2010)
  3. Heemstra, P.C. and Randall, J.E. (1993) FAO species catalogue. Volume. 16. Groupers of the world (Family Serranidae, Subfamily Epinephelinae). An annotated and illustrated catalogue of the grouper, rockcod, hind, coral grouper and lyretail species known to date. Food and Agriculture Organisation of the United Nations, Rome.
  4. Brule, T. and Canche, L.R.G. (1993) Food habits of juvenile red groupers , Epinephelus morio, from Campeche Bank, Tucatan, Mexico. Bulletin of Marine Science, 52: 772-779.
  5. Smithsonian Marine Station at Fort Pierce (February, 2010)
  6. Arreguin-Sanchez, F. and Valero, E. (1998) Trophic role of the red grouper (Epinephelus morio) in the ecosystem of the northern continental shelf of Yucatan, Mexico. In: Arreguin-Sanchez, F., Munro, J.L., Balgos, M.C. and Pauly, D. (Eds) Biology, fisheries and culture of tropical groupers and snappers. International Centre for Living Aquatic Resources Management, Philippines.
  7. Burgos, R. and Defo, O. (2004) Long-term population structure, mortality and modelling of a tropical multi-fleet fishery: the red grouper Epinephelus morio of the Campeche Bank, Gulf of Mexico. Fisheries Research, 66: 325-335.