Goliath Grouper (Epinephelus itajara)
The giant of the grouper family, the goliath (formerly called jewfish) has brown or yellow mottling with small black spots on the head and fins, a large mouth with jawbones that extend well past its small eyes and a rounded tail. It also has five dark body bands or stripes that are most visible on young goliath.
Goliath grouper is the largest of the western north Atlantic groupers. It can reach nearly 800 pounds (455 kg) and a length of 8 feet or more. The Florida record goes to a 680-pound goliath caught off Fernandina Beach in 1961. Several newspaper articles between 1920 and 1950 documented angler accounts of catching large goliath groupers, particularly in the Florida Keys, ranging between 50 and 450 pounds. Additionally, an 1895 account from the New York Times references two goliath groupers caught off Texas at 1,500 and 954 pounds.
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Goliath grouper have been targeted both commercially and recreationally at least since the late 1800s. Traditionally, they have been caught by hook and line, spearguns and as bycatch in traps and trawls. Historically, the majority of landings were reported during the spawning season.
Goliath grouper populations dramatically declined throughout their range during the 1970s and 1980s due to increased fishing pressure from commercial and recreational fishers and divers. This led to their prohibition from harvest in U.S. waters in 1990. Goliath grouper populations have substantially recovered since the harvest prohibition took effect. However, it is not clear as to when they may fully recover and when harvest restrictions could be relaxed. Difficulties in these estimates are due to unknown levels of fishing mortality rates associated with illegal harvest and release mortality.
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Male goliath grouper cannot be visually distinguished from females by body shape or color as in other members of its family. Fish mature at 5 or 6 years of age when they are just over 3 feet in length. Goliath grouper are relatively long-lived, with a maximum known age to be at least 37 years old. However, this data came from highly exploited and extremely low level populations. Some scientists estimate that these fish may have the ability to live over 50 or even 100 years.
When not feeding or spawning, adult goliath groupers are generally solitary, sedentary and territorial, making them an easy target for filming and spearfishing. Before the goliath grouper reaches full-size it is susceptible to the attack of barracuda, king mackerel and moray eels, as well as sandbar and hammerhead sharks. Once fully grown, humans and large sharks are the goliath grouper's only predators.
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Goliath grouper are opportunistic predators and feed mostly on slow-moving, bottom-associated species. Calico crabs appear to make up the majority of their diet, with other invertebrate species and fish filling in the rest. Goliath grouper will occasionally feed on fish that are struggling on a fishing line, but they have not been shown to actively hunt down fast, free swimming fish such as snappers and groupers. Prey is ambushed, caught by a rapid expansion and opening of the mouth that allows prey to be sucked in and swallowed whole.
There is insufficient scientific evidence to determine whether goliath groupers are protogynous hermaphroditic (i.e., change from females to males) like other members of its family including red, gag and Nassau groupers.
Reproductive maturity first occurs in fish 5 or 6 years of age (about 36 inches in length) due to their slow growth rate. Males mature at a smaller size (about 42 inches) and slightly younger age than females. Females first mature at 6-7 years of age and 47-53 inches in length. In the eastern Gulf of Mexico during the late 1980's, there were about 1.75 females for every male.
In the eastern Gulf, goliath grouper have been known to form spawning groups of 100 individuals or more, however, the number of individuals in spawning aggregations declined in the 1980's. These groups occur at consistent sites such as wrecks, rock ledges and isolated patch reefs during July, August and September. Studies have shown fish may move up to 62 miles (100 km) from inshore reefs to these spawning sites. In southwest Florida, presumed courtship behavior has been observed during the full moons in August and September. It is thought that goliath groupers are dispersal spawners, meaning female eggs and male sperm are released and mix in open offshore waters. The fertilized eggs develop into kite-shaped larvae as they drift in the water column for up to several months before settling down into suitable benthic (seabed and bottom of the water column) habitat during November through January, also indicating a summer spawning period.
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Once the free floating goliath grouper eggs hatch, the larval goliath spend an additional six weeks floating in the sea. They settle in shallow mangrove habitat, first in mangrove leaf litter and then along mangrove shorelines. The juvenile stage lasts 5 or 6 years in this mangrove habitat, after which fish move into to shallow reefs, eventually joining adult populations offshore. Their distribution in mangroves depends on local water quality, particularly dissolved oxygen content (more than 4 parts per million) and salinity (more than 10 parts per thousand). Other important habitat for juveniles includes seagrass beds and oyster reefs. Goliath is the only grouper species that exploits the brackish waters of estuaries as young fish. Once young adults (age 5 or 6) grow to a certain size, they move to offshore natural hard bottom or artificial reef structures.
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Goliath grouper were historically found in tropical and subtropical waters of the Atlantic Ocean, both coasts of Florida and from the Gulf of Mexico down to the coasts of Brazil and the Caribbean. The bulk of the species abundance appears to exist from the Palm Beach area through the Florida Keys, and along the west coast of Florida. They also occur along the western African coast from Senegal to Congo and are present in the eastern Pacific from the Gulf of California to Peru.
Juveniles up to about 3 feet are found in mangroves, particularly in the Ten Thousand Islands area off southwest Florida, which seems to be its center of abundance and may serve as critical nursery habitat.
In waters off of Florida, most adults are found on shallow artificial and natural reefs, the deepest being about 150 feet. These adults seem to prefer habitat with overhangs, bridges, piers and shipwrecks. Generally, they occur in areas such as deep crevices, holes and overhead structure that are thought to provide shelter and protection. Large adults exhibit little movement within reef areas and generally show the greatest movement during the presumed spawning season and when inshore temperatures are low.
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Pressures on Population
Goliath grouper have been targeted both commercially and recreationally since at least the late 1800s. Goliath grouper are extremely vulnerable to exploitation due to a combination of life history traits such as slow growth, long life, late sexual maturity, strong site fidelity and the formation of spawning aggregations. These characteristics combined with increasing fishing pressure led to the state and federal protection status in 1990. The species was listed as a candidate for the Species of Concern list under the U.S. Endangered Species Act, but was removed by NOAA Fisheries in 2006 due to its increasing population and expanding geographic distribution.
Juvenile goliath grouper recruit to mangrove habitat throughout their range. Nearly all of the existing mangrove habitat in the entire United States occurs along the west Florida coast. This habitat has declined in Florida since the early 1900s due to the redirection of freshwater flow from the Everglades through methods such as channelization; mosquito-abatement; and development for agricultural, industrial and residential purposes. Much of this habitat loss occurred prior to 1970, though some was later. For example, between 1987 and 2000, 9% of mangroves were destroyed. In some areas studied throughout the state, overall mangrove habitat loss has ranged from 22-86%. Because mangroves serve as important juvenile habitat for these fish, their loss could affect population recovery even if reproductive levels of adult fish are high. Additionally, goliath grouper are very vulnerable to cold temperatures and red tide.
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