Parrish et al. (2008) used CRITTERCAMS fitted on Hawaiian Monk Seals to study interactions during foraging between the seals and large predatory fish, including the Greater Amberjack. Greater Amberjacks are quick and more agile than the seals, but showed much less ability to detect and flush benthic prey from cover. The seals use their whiskers to brush along the bottom and chase out camouflaged prey. They can also dig out wrasses and eels that are buried deep in the sand bottom and they easily flip large rocks (~20 kg) to obtain prey items hiding beneath. The jacks’ awareness of such behavior enables them to swim ahead of the seal and wait near a rock until the seal arrives and moves the rock, flushing prey items from cover. Parrish et al. found that the jacks routinely positioned their mouths within inches of the seal’s nose to maximize their chances of snatching prey items flushed by the bottom-probing of the seal. On numerous occasions they were observed capturing prey before the seal could catch it.
Andaloro and Pipitone (1997) studied the stomach contents of 308 adult Greater Amberjack in the Mediterranean Sea. They found that fish occurred in 79.7% of non-empty stomachs, accounting for 79.5% of prey in number and 71.0% in weight; cephalopods occurred in 26.8% of non-empty stomachs, accounting for 20.5% of prey in number and 29.0% in weight. Overall, pelagic prey items were less frequent than demersal (dwelling near the sea bottom) ones; moreover, males fed much more intensely on demersal prey than did females.
In laboratory experiments, Greater Amberjacks were strictly diurnal feeders and this circadian pattern is apparently driven by a strong endogenous clock, with the pattern persisting for many weeks even under conditions of constant light (Chen et al. 2007).
The Greater Amberjack (Seriola dumerili) is a member of the Jack family, which consists of typically large, fast-swimming fishes of tropical and warm-temperate seas, occurring from coastal bays and lagoons to open ocean (Robins and Ray 1986).
The Greater Amberjack is currently listed by the National Marine Fisheries Service as overfished in the Gulf of Mexico (NMFS 2008, Federal Register, 73 FR 16829-16830).
The Greater Amberjack has a nearly worldwide distribution in warm waters; in the western Atlantic, it is found from Massachusetts (U.S.A.) to southeastern Brazil (Robins and Ray 1986).
The Greater Amberjack is widely distributed in the Mediterranean, Atlantic and Western Pacific (Porta et al. 2009).
The Greater Amberjack is widely distributed in the Atlantic, Pacific, and Indian Oceans (Harris et al. 2007).
Renshaw et al. (2007) developed microsatellite markers for the Greater Amberjack with the hope that they would be useful for conservation and population genetic studies of both wild and "domesticated" stocks of this fish.
The Greater Amberjack is found in the open sea to 200 fathoms; small specimens occur in shallow water (Boschung et al. 1983).
In a study of Greater Amberjacks in the southeastern United States (Manooch and Potts 1997), the oldest individual examined was 17 years old. In another study, in the north-central Gulf of Mexico, maximum age was estimated to be 15 years (Thompson et al. 1999). In a study of nearly 2000 specimens collected from North Carolina to the Florida Keys, age estimates ranged from 1 to 13 years (Harris et al. 2007).
The Greater Amberjack is mostly brownish (darker above, whitish below), often with a broad, diffuse, yellowish stripe along the midside. A dark olive-brown stripe extends from the snout through the eye to the point where the spinous dorsal fin begins. The spinous dorsal fin is low, but easily seen at all sizes (usually with 7 spines). The front lobe of the soft dorsal and anal fins is not very high; the outer edge is curved, but not sickle-shaped. The head is bluntly pointed. There is a fleshy keel on each side of the causal peduncle. There are no detached finlets. (Robins and Ray 1986)
The maxilla (the rear bone of the upper jaw) is very broad posteriorly (i.e., toward the rear) reaching the middle of the eye. The pectoral fins are shorter than the head, equalling the pelvic fins. The second dorsal fin is much longer than the anal fin. The caudal peduncle is relatively deep, with grooves present above and below at the base of the caudal fin. (Boschung et al. 1983)
Based on an examination of about 2500 Greater Amberjack collected from North Carolina to the Florida Keys, Harris et al. (2007) estimated potential fecundity at 18,271,400 to 59,032,800 oocytes for 930 to 1,296 mm specimens and from 25,472,100 to 47,194,300 oocytes for ages 3 to 7. Peak spawning off south Florida and the Florida Keys occurred during April and May.
The flesh of the Greater Amberjack can cause ciguatera poisoning (Robins and Ray 1986; Poli et al. 1997) if it has fed on other fishes that have been contaminated with toxins produced by certain dinoflagellate algae, notably Gambierdiscus toxicus.
The Greater Amberjack may reach 1.5 meters and 80 kg (Robins and Ray 1986).
The Greater Amberjack is an important game fish (Robins and Ray 1986).
The Greater Amberjack is of high commercial value in worldwide fisheries. The interest in this species in aquaculture is increasing due to its fast growth, low mortality, and good performance, having now been cultured successfully in Japan for some years, as well as in the Mediterranean and Atlantic. (Porta et al. 2009 and references therein)
