Longtail tunaLOT

 
~70 cm FL

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

Colour:

Bluish black above, silvery white below with horizontal rows of white/silver elongate spots on belly, finlets yellowish with grey edges.

Size:

Up to 150 cm TL and 35.9 kg in weight.1

Distribution:

Tropical and warm temperate waters of the Indo–West Pacific.

View FAO distribution map

Habitat:

Inshore pelagic, preferring temperatures of 26 °C and found at depths from the surface to at least 80 m.

Biology:

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

Indonesian fisheries:

Caught by gillnetting, purse seining and trolling.

Similar species:

 
Thunnus alalunga
Albacore tuna
Thunnus alalunga
Thunnus alalunga differs in having pectoral fins very long, extending to second dorsal finlet (vs. moderate in length, not reaching beyond second dorsal-fin base); posterior portion of body (from deepest point to caudal peduncle) moderate relative to FL (vs. long); body markings as white/silver horizontal to oblique, incomplete stripes present in stressed live, and freshly dead specimens only (vs. horizontal rows of white/silver elongate spots on belly); ventral surface of liver striated, lobes roughly equal in length (vs. not striated, right lobe elongate) and 25–31 gill rakers on first gill arch (vs. 19–27).
 
Thunnus alalunga
Yellowfin tuna
Thunnus albacares
Thunnus albacares differs in having pectoral fins moderate in length, reaching beyond origin of second dorsal fin (vs. not reaching origin of second dorsal fin); posterior portion of body (from deepest point to caudal peduncle) moderate relative to FL (vs. long); white/silver body markings in regularly spaced, vertical lines and alternating lines of spots in a ‘chevron’ pattern (vs. horizontal rows of white/silver elongate spots on belly) and 26–34 gill rakers on first gill arch (vs. 19–27).
 
Thunnus maccoyii
Southern bluefin tuna
Southern bluefin tuna
Thunnus maccoyii differs in having short pectoral fins, not reaching past interdorsal space; (vs. moderate in length, not reaching origin of second dorsal fin); posterior portion of body (from deepest point to caudal peduncle) moderate relative to FL (vs. long); white/silver irregularly spaced, often broken or incomplete vertical stripes present in stressed live specimens only, otherwise silver/white below (vs. horizontal rows of white/silver elongate spots on belly); ventral surface of liver striated, lobes roughly equal in length (vs. not striated, right lobe elongate); 31–34 gill rakers on first gill arch (vs. 19–27) and a yellow median keel in adults (vs. dark).
 
Thunnus obesus
Bigeye tuna
Thunnus obesus
Thunnus obesus differs in having pectoral fins very long, extending to second dorsal finlet (vs. moderate in length, not reaching beyond second dorsal-fin origin); posterior portion of body (from deepest point to caudal peduncle) moderate relative to FL (vs. long); white/silver body markings in irregularly spaced, vertical, often broken lines (vs. horizontal rows of white/silver elongate spots on belly); ventral surface of liver striated, lobes roughly equal in length (vs. not striated, right lobe elongate) and 23–31 gill rakers on first gill arch (vs. 19–27).
 
Thunnus orientalis
Pacific bluefin tuna
Pacific bluefin tuna
Thunnus orientalis differs in having pectoral fins short in length, not reaching interdorsal space (vs. moderate not reaching origin of second dorsal fin); posterior portion of body (from deepest point to caudal peduncle) moderate relative to FL (vs. long); white/silver markings as vertical lines and alternating lines of spots, mostly confined to lower portion of body (vs. horizontal rows of white/silver elongate spots on belly) and ventral surface of liver striated, lobes roughly equal in length (vs. not striated, right lobe elongate).

Internal links:

Thunnus tonggol market gallery

External links:

FishBase
The IUCN Red List of Threatened SpeciesTM

References

  1. 1.
    Collette BB, Nauen CE. FAO species catalogue. Volume 2. Scombrids of the world. An annotated and illustrated catalogue of tunas, mackerels, bonitos and related species known to date. 1983.
  2. 2.
    Griffiths SP, Fry GC, Manson FJ, Lou DC. Age and growth of longtail tuna (Thunnus tonggol) in tropical and temperate waters of the central Indo-Pacific. ICES Journal of Marine Science. 2010;67(1):125–34.
  3. 3.
    Boonragsa V. Tuna resources in the Thai waters, Andaman Sea. Paper presented at the second meeting of the Working Group on Tuna in the Andaman Sea Area. In: Expert Consultation on Stock Assessment of Tunas in the Indian Ocean Colombo (Sri Lanka) 4-8 Dec 1986. 1987.
  4. 4.
    Abdussamad EM, Koya KP, Ghosh S, Rohit P, Joshi KK, Manojkumar B, et al. Fishery, biology and population characteristics of longtail tuna, Thunnus tonggol (Bleeker, 1851) caught along the Indian coast. Indian Journal of Fisheries. 2012;59(2):7–16.
  5. 5.
    Wilson M. The biology, ecology and exploitation of longtail tuna, Thunnus tonggol (Bleeker) in Oceania. BSc Masters thesis, Macquarie University. New South Wales. 1981;