Latin name

Thunnus tonggol

Other name

Northern bluefin tuna

Identification

The longtail's body is torpedo-shaped, elongated, high in the midsection and tapering sharply towards the tail. The head is large with a slightly protruding lower jaw. The first gill arch has 20-25 gill stamens. There are 210-220 scales on the lateral line. Swim bladder absent or rudimentary. Liver without radial striae.

Features of fish fins

The first dorsal fin has 12-14 hard rays and the second dorsal fin has 14-15 soft rays. There are 8-9 small extra fins between the second dorsal and caudal fins. The anal fin has 13-14 soft rays. There are 8-9 additional rays between the anal and caudal fins. The caudal fin is strongly emarginated, month-shaped. The second dorsal fin is slightly higher than the first. The pectoral fins are long but do not reach the vertical beginning of the base of the second dorsal fin. 

Fish colouring

The back of these fish is blue, the sides and belly are silvery white. The dorsal, pectoral and ventral fins are black. Other fins are yellow with grey edges. 

Distribution

Widespread in tropical and subtropical waters of the Indian and Pacific Oceans: Red Sea and East Africa to New Guinea, north to Japan, south to Australia. Recorded in New Zealand.

Habitat

Marine pelagic oceanodromous species, predominantly neritic, avoiding very turbid waters and areas of reduced salinity such as estuaries. Depth range from 10 to 150 metres.

Size

This species has a maximum length of 145 cm and a mass of 35.9 kg. Maximum recorded age: 19 years.

Behavior

Long-tailed tuna can form schools of varying sizes. 

Fish of this species have well-developed blood vessels in the skin and lateral body muscles and haemoglobin-rich blood. The body temperature during active swimming exceeds the water temperature by several degrees.

Food and feeding habits

The diet consists of a variety of pelagic fish such as Atherinas and sargans. It feeds on cephalopods and crustaceans, especially estuarine mussel larvae and shrimp. Occasionally, long-tailed tuna will dive into a school of forage fish and make a splash.

Reproduction

Reproduction is by spawning.

Fishing

They are a valuable commercial fish. Fishing areas: Western Pacific and Indian Ocean. Of interest to sport fishermen. 

Relationship with a person

Long-tailed tuna has tender, almost white meat that is good for canning.