Longtail tuna- Thunnus tonggol
Sep 08, 2022
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Thunnus tonggol is a species of tuna of tropical Indo-West Pacific waters.
It is commonly known as the longtail tuna or northern bluefin tuna. The usage of the latter name, mainly in Australia to distinguish it from the southern bluefin tuna, leads to easy confusion with Thunnus thynnus of the Atlantic and Thunnus orientalis of the North Pacific. Compared to these "true" bluefins, Thunnus tonggol is more slender and has shorter pectoral fins.
Characteristic features:
- Large median keel with 2 smaller keels on either side of caudal peduncle
- 19–27 gill rakers on first gill arch
- 8–10 dorsal finlets, 7–10 anal finlets
- Interpelvic process with 2 flaps
- Caudal peduncle long / body profile behind second dorsal fin elongate
- Pectoral fins short to moderate in length, not extending past second dorsal fin origin
- Ventral surface of liver not striated, right lobe elongate
Bluish black above, silvery white below with horizontal rows of white/silver elongate spots on belly, finlets yellowish with grey edges.
Up to 150 cm TL and 35.9 kg in weight.1
Tropical and warm temperate waters of the Indo–West Pacific.
Inshore pelagic, preferring temperatures of 26 °C and found at depths from the surface to at least 80 m.
Feeds on a variety of fish, cephalopods and crustacean. Forms large schools. Longtail tuna possibly grow more slowly and live longer than other similarly sized tuna species.2 Maturity varies by location – in Thailand size of first maturity for females was 34 cm FL, with 50% of females being mature at 39.6 cm FL. Age of first maturity in Thailand is estimated at 2 years.3 Estimated maximum age is recorded at 4.5 years in Indian waters,4 10 years in Australia5 and may live up to 18 years in the central Indo-Pacific.2