Taxonomy/Related Species: Animalia Chordata Actinopterygii Perciformes Scombridae Thunnus tonggol

Description & Behavior

Longtail tuna, Thunnus tonggol (Bleeker, 1851), aka blue fin tuna, bonitos, Indian long-tailed tunas, northern bluefin, northern bluefin tuna, oriental bonitos, and tuna, are in the Family Scombridae which includes the albacores, bonitos, mackerels, and tunas.

Longtail tunas are dark blue to black dorsally (on top), with silvery white bellies and lower sides. Colorless oval spots are arranged horizontally along their bellies. Their second dorsal and anal fins have yellow hues, while their caudal (tail) fins are blackish with yellow-green streaks. Their second dorsal fins are higher than their first, and their pectoral fins are short to moderately long in size. Max size and weight recorded is 145 cm and 35.9 kg respectively, while their common length is about 70 cm.

Longtail tunas seem to avoid turbid waters, and form schools of varying sizes.

World Range & Habitat

The tropical neritic zone (the shallow part of the sea along the coast, above the continental shelf) is what longtail tunas call home. They avoid turbid areas, as well as areas with decreased salinity, such as estuaries. Their range of the Indo-West Pacific includes the Red Sea and East Africa to New Guinea, south to Australia, and north to Japan.

Feeding Behavior (Ecology)

Longtail tunas feed on a variety of fishes, cephalopods, and crustaceans. They seem to particularly like stomatopod larvae and prawns.

Life History

Little is known about the reproduction of longtail tunas.

Conservation Status & Comments

Longtail tunas are a highly commercially harvested species for food. The IUCN has not evaluated their conservation status, but the collapse of the populations of other tuna species due to overfishing gives cause for concern. They are a moderate to highly vulnerable species.

Resilience to fishing pressure: Medium, minimum population doubling time 1.4 – 4.4 years
Extinction vulnerability to fishing: Moderate to high vulnerability (47 of 100)

References & Further Research

FAO Species Catalogue. Vol. 2. Scombrids of the world. An annotated and illustrated catalogue of Tunas, Mackerels, Bonitos and related species known to date.Collette, B.B. & C.E. Nauen 1983.. FAO Fish. Synop., (125) Vol.2:137 p.

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