Black jack

Caranx lugubris, the black jack, black trevally, black kingfish, coal fish or black ulua, is a species of large ocean fish in the jack family Carangidae. The species has a circumtropical distribution, found in oceanic, offshore waters of the tropical zones of the Pacific, Atlantic and Indian Oceans. The species is particularly prevalent around offshore islands such as the Caribbean islands in the Atlantic, Hawaii and French Polynesia in the Pacific and the Seychelles and Maldives in the Indian Ocean. Black jack are rare in shallow waters, preferring deep reefs, ledges and seamounts in clear waters. The species is easily distinguished by its black to grey fins and jet black scutes, with the head having a steep profile near the snout. The largest recorded length is 1 m and weight of 17.9 kg. The black jack lives either individually or in small schools, and is known to school with other species. It is a predatory fish, taking a variety of fish, crustaceans and molluscs as prey. Sexual maturity is reached at 34.6 cm in females and 38.2 cm in males, with spawning taking place between February and September in the Caribbean. The early life history of the species is very poorly understood. Black jack are of high importance to many island fisheries, but are rarely encountered in most continental fisheries. The species has a reputation as a gamefish, and is variably considered a terrible or excellent food fish, although several cases of ciguatera poisoning have been attributed to the species. The species was initially named Caranx ascensionis by Georges Cuvier, however several issues with the use of this name have seen Felipe Poey's name Caranx lugubris become the valid scientific name.

Distribution

The black jack has a circumtropical distribution, meaning their range extends around the Earth's equatorial oceans, thereby inhabiting the tropical and subtropical regions of the Atlantic, Pacific and Indian Oceans. In the Indian Ocean, they are found from Natal, South Africa in the west to northern Australia in the east. They are patchily distributed along the east African and Asian coastline in the Indian Ocean, being absent from both the Persian Gulf and Red Sea, as well as several countries bordering the ocean. The species is widely known from many Indian Ocean islands including the Seychelles, Réunion, Mauritius and Cargados Carajos In the Pacific Ocean, the black jack is known from parts of the Indonesian-Australian archipelago north to Japan, and through many of the Pacific Islands such as Hawaii, New Caledonia and Tonga. The species range in the eastern Pacific has been ranges from Mexico and the Revillagigedo Islands in the north to Costa Rica in the south. In the western Atlantic Ocean, black jack have been found from North Carolina in the U.S. south to Rio de Janeiro, with the species most common in the Caribbean and the northern Gulf of Mexico. In the eastern Atlantic, the species has been reported from the Azores, Madeira St. Paul's Rocks, Ascension Island, and the Gulf of Guinea.

The black jack is a benthopelagic species rarely found in shallow inshore waters, preferring deep, clear offshore waters of depths from 12 to 354 m. The species is most common in insular oceanic habitats and around offshore islands, rarely found close to the continents. The black jack inhabits deep reefs and reef drop offs, also being common around oceanic seamounts. It has been recorded from lagoons in the Solomon Islands.