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Species: itajara Common Names English language common names include goliath grouper, jewfish, blackbass, esonue grouper, giant seabass, grouper, hamlet, southern jewfish, and spotted jewfish. Photo courtesy Kenneth Krysko Of historical importance to commercial fisheries, the goliath grouper has also long been prized by recreational and sport fishers.
Traditionally, the species has been caught primarily by hook and line, traps, and trawls. Spear fishers find this fish easy to approach; hence in locations accessible to divers their numbers have declined. The flesh is of excellent quality. Danger to Humans Very large goliath grouper have been observed to stalk divers and even conduct unsuccessful ambushes of the same.
Large individuals of this species should be treated with caution. Conservation The large size, slow growth, low reproductive rate, and spawning behavior have made the goliath grouper especially susceptible to overfishing.
Historical exploitation of goliath grouper annual spawning aggregation sites greatly reduced the number of reproductive adults. As goliath grouper are slow growing and require several years to reach sexual maturity, recovery for this species is expected to be slow. Geographical Distribution World distribution map for the goliath grouper The goliath grouper occurs in the western Atlantic Ocean from Florida south to Brazil, including the Gulf of Mexico and the Caribbean Sea.
Habitat Occurring in shallow, inshore waters to depths of feet 46 m , the goliath grouper prefers areas of rock, coral, and mud bottoms. Strikingly patterned juveniles inhabit mangroves and brackish estuaries, especially near oyster bars.
The goliath grouper is notable as one of the few groupers found in brackish waters. This fish is solitary by nature, with the adults occupying limited home ranges. It is territorial near areas of refuge such as caves, wrecks, and ledges, displaying an open mouth and quivering body to intruders. This sound travels great distances underwater and is also used to locate other goliath grouper.
Biology Goliath grouper. The body is robust and elongate; its widest point is more than half its total length. The head is broad with small eyes. The dorsal fins are continuous with the rays of the soft dorsal longer than the spines of the first dorsal fin.
The membranes between the dorsal fin elements are notched. Pectoral fins are rounded and noticeably larger than the pelvic fins. Bases of the soft dorsal and anal fins are covered with scales and thick skin. The caudal fin is rounded. Coloration This fish is generally brownish yellow, gray, or olive with small dark spots on head, body, and fins.
Large adults are somber-colored. Three or four irregular faint vertical bars are present of the sides of individuals less than 3 feet 1m in length. The rear half of the caudal penduncle of these small individuals is covered by another similar bar. The tawny colored juveniles, although not as colorful as some grouper species, are attractively patterned; exhibiting a series of dark, irregular, vertical bands and blotches. Dentition Goliath grouper have three to five rows of teeth in the lower jaw.
The presence of a number of short weakly developed canine teeth is useful in distinguishing this species from other North Atlantic groupers. Coral bottoms are a preferred habitat of the goliath grouper. Growing to lengths of 8. In Florida, the largest hook and line captured specimen weighed pounds kg.
The oldest verifiable goliath grouper on record is 37 years. However, this specimen was sampled from a population of individuals depressed by fishing pressure and it is projected that goliath grouper may live much longer, perhaps as much as 50 years. Males achieve sexual maturity at four to six years of age and lengths of inches cm , females at six to seven years of age and inches cm.
Growth rates are slow, averaging approximately four inches 10 cm per year until the age of six years. Growth declines to about 1. Goliath grouper feed on the spiny lobster. Prey is ambushed, caught with a quick rush and snap of the jaws. The sharp teeth are adapted for seizing prey and preventing escape although most prey is simply engulfed and swallowed whole.
Reproduction Many groupers are protogynous hermaphrodites — a condition in which individuals first mature as females only later to become males. And although goliath grouper are assumed to conform to this reproductive mode, a study of the age, growth, and reproduction of the species found no transitional individuals, the most direct evidence of sex reversal.
However, the significance of this finding is of diminished value when one considers that transitional individuals are known to be rare amongst confirmed species of protogynous hermaphrodites, such as the red grouper Epinephelus morio and gag Mycteroperca microlepis. Additionally, exceptions to the rule of protogyny within a species may be common. One author offers three potential exceptions that may explain why some sexually mature male goliath groupers are smaller than some mature females — a scenario that at first would seem to be contradictory for a protogynous hermaphrodite.
Kite-shaped Epinephelus larvae. Photo courtesy National Marine Fisheries Service In support of the notion that the species is a protogynous hermaphrodite is the fact that the largest goliath groupers are invariably male. Spawning goliath grouper form impressive offshore aggregations of up to or more individuals.
Ship wrecks, rock ledges, and isolated patch reefs are preferred spawning habitat. Since receiving legislative protection the spawning aggregations of goliath grouper have risen to individuals per location. The females release eggs while the males release sperm into the open offshore waters. After fertilization, the eggs are pelagic, dispersed by the water currents.
Upon hatching, the larvae are kite-shaped, with the second dorsal-fin spine and pelvic fin spines greatly elongated. These pelagic larvae transform into benthic juveniles at lengths of one inch 2.
Predators Predators of groupers include large fish such as barracuda, king mackerel and moray eels, as well as other groupers. The sandbar shark Carcharhinus plumbeus and the great hammerhead shark Sphyrna mokarran are also known to feed on groupers. Large adults of this species likely have very few natural predators. Taxonomy The German ichthyologist M. Lichtenstein described the goliath grouper as Serranus itajara in an publication regarding the natural history of Brazil. Synonyms of E. A number of authors treat the name Promicrops itajara as valid taxonomy for the goliath grouper.
Prepared by: Robert H.
Species: itajara Common Names English language common names include goliath grouper, jewfish, blackbass, esonue grouper, giant seabass, grouper, hamlet, southern jewfish, and spotted jewfish. Photo courtesy Kenneth Krysko Of historical importance to commercial fisheries, the goliath grouper has also long been prized by recreational and sport fishers. Traditionally, the species has been caught primarily by hook and line, traps, and trawls. Spear fishers find this fish easy to approach; hence in locations accessible to divers their numbers have declined. The flesh is of excellent quality. Danger to Humans Very large goliath grouper have been observed to stalk divers and even conduct unsuccessful ambushes of the same. Large individuals of this species should be treated with caution.