The Bluefin Trevally is a species of large, widely distributed marine fish classified in the jack family, Carangidae. The species grows to a maximum known length of 117 cm and a weight of 43.5 kg, however is rare above 80 cm.
The Bluefin Trevally is a strong predatory fish, with a diet dominated by fish and supplemented by cephalopods and crustaceans as an adult. Juveniles consume a higher amount of small crustaceans, but transfer to a more fish based diet as they grow. The species displays a wide array of hunting techniques ranging from aggressive midwater attacks, reef ambushes and foraging interactions with other larger species, snapping up any prey items missed by the larger animal. The Bluefin Trevally reproduces at different periods throughout its range, and reaches sexual maturity at 30–40 cm in length and around 2 years of age. It is a multiple spawner, capable of reproducing up to 8 times per year, releasing up to 6 million eggs per year in captivity. Growth is well studied, with the fish reaching 194 mm in its first year, 340 mm in the second and 456 mm in the third year.
The Bluefin Trevally is a popular target for both commercial and recreational fishermen. Commercial fisheries record up to 50 tonnes of the species taken per year in the west Indian Ocean, and around 700 lbs per year in Hawaii. The rapid decimation of the Hawaiian population due to overfishing has led to increased research in the aquaculture potential of the species, with spawning achieved in captivity.
Despite its popularity as a table fish, many cases of ciguatera poisoning have been reported from the species.
It is similar in shape to a number of other large jacks and trevallies, having an oblong, compressed body with the dorsal profile slightly more convex than the ventral profile, particularly anteriorly. This slight convexity leads to the species having a much more pointed snout than most other members of Caranx. The dorsal fin is in two parts, the first consisting of 8 spines and the second of 1 spine followed by 21 to 24 soft rays. The anal fin consists of 2 anteriorly detached spines followed by 1 spine and 17 to 20 soft rays. The pelvic fins contain 1 spine and 20 soft rays. The caudal fin is strongly forked, and the pectoral fins are falcate, being longer than the length of the head. The lateral line has a pronounced and moderately long anterior arch, with the curved section intersecting the straight section below the lobe of the second dorsal fin. The curved section of the lateral line contains 55-70 scales while the straight section contains 0 to 10 scales followed by 27 to 42 strong scutes. The chest is completely covered in scales. The upper jaw contains a series of strong outer canines with an inner band of smaller teeth, while the lower jaw contains a single row of widely spaced conical teeth. The species has 25 to 29 gill rakers in total and there are 24 vertebrae present. The eye is covered by a moderately weakly developed adipose eyelid, and the posterior extremity of the jaw is vertically under or just past the anterior margin of the eye. Despite their wide range, the only geographical variation in the species is the depth of the body in smaller specimens.
You should be able to land pretty much any Bluefin Trevally on 50lb braid and a heavy bait casting or spinning outfit. Make sure you pull hard to get them away from the reefs where they live. They don't usually immediately go under rocks, but they sometimes will cut you off. You should go equipped with a high quality spinning reel. For the small ones near shore, you could use a 4500 series reel with a long spinning rod for long casts. For larger fish, usually found farther from shore, large poppers and jerkbaits will work well.
Catch them fast - Bluefin Trevally like to chase things and will have no interest in a slow moving lure retrieved steadily. Cast them over submerged rocks and retrieve them steadily so that they swing back and forth until they get hammered.
For smaller Bluefin Trevally, you should use a clear plastic bobber or float, fill it with water, and then use a soft plastic about a meter (30”) past the bobber. You cast this as far as you can and immediately start reeling it in quickly while popping the rod tip every few seconds. This causes the plastic bobber to splash water and attracts the Bluefin Trevally, which come to investigate the commotion and then inhale the soft plastic.
The Bluefin Trevally is widely distributed, occupying the tropical and subtropical waters of the Indian and Pacific Oceans, ranging along the coasts of four continents and hundreds of smaller islands and archipelagos. In the Indian Ocean, the species easternmost range is the coast of continental Africa, being distributed from the southern tip of South Africa north along the east African coastline to the Red Sea and Persian Gulf. The species' range extends eastwards along the Asian coastline including Pakistan, India and into South East Asia, the Indonesian Archipelago and northern Australia. The southernmost record from the west coast of Australia comes from Exmouth Gulf. Elsewhere in the Indian Ocean, the species has been recorded from hundreds of small island groups including the Maldives, Seychelles, Madagascar and the Cocos (Keeling) Islands.
The Bluefin Trevally is abundant in the central Indo-Pacific region, found throughout all the archipelagos and offshore islands including Indonesia, Philippines and Solomon Islands. Along continental Asia, the species has been recorded from Malaysia to Vietnam and mainland China. Its offshore range does extend north to Hong Kong, Taiwan and southern Japan in the north western Pacific. In the south, the species reaches as far south as Sydney in Australia. Its distribution continues throughout the western Pacific including Tonga, Western Samoa and Polynesia, and the Hawaiian Islands. The easternmost limit of the species distribution is the Mesoamerican coastline between Mexico and Ecuador in the central eastern Pacific, including islands such as the Galápagos Islands.
In Australia it occurs from Margaret River, Western Australia, around the tropical north and south to the central coast of New South Wales.