Atlantic Giant Grouper

Atlantic Giant Grouper, Epinephelus itajara

The Atlantic Giant Grouper, Epinephelus itajara, whose common Spanish name is cherna gigante, is a member of the Grouper or Epinephelidae Family, known collectively as cabrillas and garropas in Mexico. This fish is also known as the Atlantic Goliath Grouper, the Goliath Grouper, and the Jewfish. Globally, there are one hundred species in the genus Epinephelus, eleven of which are found in Mexican waters, six in the Atlantic and five in the Pacific.

The Atlantic Giant Groupers are the largest fish in the Atlantic Ocean with very large and robust bodies that can be half as deep as they are long. Juveniles are strikingly colored with a series of dark irregular vertical bands and blotches on their sides; they transition to a drab uniform brownish yellow, gray, or green as they mature, which allows them to blend into their habitat. Their head, fins, and dorsal portions of their body are covered with small black spots. Their head is extremely broad with a rounded snout and small beady eyes. They have rounded finely serrated gill covers with three flat spines, the middle spine being the longest. Their mouth is modestly-sized, extends past the eyes, and has three to five rows of teeth on the lower jaw. Their anal fin has 3 spines and 8 rays; their caudal fin is short, rounded, and fan-like; their dorsal fin is continuous with 11 spines and 15 or 16 rays (the rays are longer than the spines); and their pectoral fins are rounded and larger than the pelvic fins. They have 21 to 24 gill rakers and are covered with rough scales.

The Atlantic Giant Groupers are large solitary fish found in shallow coastal tropical waters within rock, coral, and muddy bottoms at depths up to 330 feet. They reach a maximum length of 2.5 meters (8 feet 2 inches) and 360 Kg (790 pounds) in weight. Juveniles are found in brackish estuaries within mangroves and in close proximity to oyster bars. Large adults also frequent mangrove estuaries but are predominantly found in shallow coast reef environments. They have limited home ranges and normally have the ability to take refuge in caves or wrecks. They consume crustaceans including spiny lobsters, octopuses, sea turtles, and fish including barracuda, sharks, and stingrays with most prey being swallowed whole. Juveniles are preyed upon by barracuda, hammerhead sharks, king mackerels, moray eels, sandbar sharks, as well as other groupers. Adults are free from predation. They are known to defend their territories with aggressive body language and rumbling sounds, which is also used as a form of interspecies communication. Reproduction of the Atlantic Giant Grouper is not well understood but most likely involves protogynous hermaphrodites, where fish are born female and change to male at midlife. Males mature at smaller sizes and younger ages than females but are outnumbered by two to one in native populations. They aggregate in groups of up to one hundred individuals in relatively shallow water in close proximity to ship wrecks, rock ledges, and isolated patch reefs to spawn at specific times and locations for periods that can be as long as two weeks. Each female releases between thirty nine and fifty seven million eggs during these periods which are fertilized externally by males. The eggs and larvae are pelagic. Within thirty days of hatching, the one-inch juveniles settle out in shallow water mangrove environments where they remain for up to six years before they transition to deeper waters. They have exceedingly slow growth rates averaging four inches per year until age six, then 1.2 inches per year until age fifteen, and finally 0.4 inches per year after age twenty five. Females can live up to at least thirty seven years and males up to twenty six years. They were successfully bred in captivity for the first time in 2015.

In Mexican waters the Atlantic Giant Groupers are found in all waters of the Atlantic and are abundant throughout the Caribbean.

The Atlantic Giant Grouper is straightforward to identify due to its large size. It is also the only grouper found in Mexican waters of the Atlantic with spots that are limited to the first half of the body. It is virtually identical to the Pacific Goliath Grouper, Epinephelus quinquefasciatus, found in the Pacific. Historically they were believed to be one and the same species, however, the Atlantic Giant Grouper was recently separated as a new stand alone species.

Due to their size, relatively shallow water habitat, and spawning in large aggregations in known locations at known times of the year, the Atlantic Giant Groupers have historically been a prized catch for recreational and commercial anglers and subject to mass harvesting with hook and line, traps, and trawls. Due to their inquisitive and fearless nature and slow movements, they are easy prey for spearfishermen. Their flesh is of excellent quality and marketed fresh and frozen. Population sizes are difficult to access as they are widespread with normally only one fish found within one reef. Due to their habit of congregating at known locations for known periods each year they are sitting ducks for both recreational and commercial fishermen. From a conservation perspective they are currently classified as Critically Endangered. Population declines have been estimated to be at the 80% level over the last ten years attributed to overfishing. Fishing moratorium have now been in place for the last twenty five years. In some areas that ban the harvesting of the species they appear to be making a slow recovery based on sightings of small fish. Mortality is high for catch and release fish and widespread poaching is known to occur. They are also prone to juvenile habitat loss (mangroves) and are vulnerable to cold water and red tide episodes.  Very large specimens are known to stalk and ambush divers.

Atlantic Giant Grouper, Epinephelus itajara, Juvenile. Fish caught from coastal waters off Key West, FL, December 2015. Length: 94 cm (37 inches). Catch, photo and identification courtesy of Dean Kimberly, Atlanta, GA.

Atlantic Giant Grouper (1)

Atlantic Giant Grouper, Epinephelus itajara. Fish caught from coastal waters off the Boca Grande Pass, Southwestern Florida, May 2016. Length: 1.6 meters (5 feet 3 inches). Weight: 75 kg (165 pounds). Relatively poor photos due to the specimen being a quick catch and release. Catch, photo, and identification courtesy of George Brinkman, Guelph, Ontario, Canada.