Thunnus orientalis

Osteichthyes Scombridae Genus Thunnus Thunnus orientalis
Pacific bluefin tuna PBF
45.3 cm FL. Source: © H. Motomura.
Characteristic features:
Colour:

Dark blue/black above grading into silver/white on sides and below; white/silver spots present in a series of dorsal-ventral rows on the lower body; finlets yellow; anal fin and second dorsal fin with yellow hues; caudal keels dark.

Size:

Up to 300 cm FL and 450 kg in weight.

Distribution:

Mostly found in temperate but also tropical waters of the Pacific Ocean, primarily in the North Pacific.

View FAO distribution map

Habitat:

Pelagic-oceanic. Tolerates a wide temperature range and is found from the surface to 550 m.1

Biology:

Feeds primarily on small schooling fish or squid, also eats sessile crustaceans. Schools by size with conspecifics and other scombrids. Reaches maturity at 100–150 cm FL, at an age of approximately 3–5 years.2 Size at 50% maturity is reached between 102–135 cm FL.3 Maximum age potentially reaches 26 years.4

Indonesian fisheries:

Caught occasionally by longline.

Similar species:

Thunnus alalunga
Albacore

Thunnus alalunga

Thunnus alalunga differs in having pectoral fins very long, extending to second dorsal finlet (vs. short never reaching dorsal interspace); and white/silver body markings as horizontal to oblique, incomplete stripes present in stressed live, and freshly dead specimens only (vs. white/silver vertical lines and alternating lines of spots).

to Thunnus alalunga

Thunnus albacares
Yellowfin tuna

Thunnus albacares

Thunnus albacares differs in having pectoral fins moderate length, not extending beyond interdorsal space (vs. short, never reaching beyond inter-dorsal space); white/silver body markings in regularly spaced, vertical lines and alternating lines of spots in a ‘chevron’ pattern (vs. white/silver markings as vertical lines and alternating lines of spots, mostly confined to lower portion of body) and ventral surface of liver not striated, right lobe elongate (vs. striated, lobes roughly equal in length).

to Thunnus albacares

Thunnus maccoyii
Southern bluefin tuna

Thunnus maccoyii

Thunnus maccoyii differs in having a series of white/silver markings as vertical lines and alternating lines of spots, mostly confined to lower portion of body (vs. white/silver irregularly spaced, often broken or incomplete vertical stripes present in stressed live specimens only, otherwise silver/white below) and a yellow median keel in adults (vs. grey).

to Thunnus maccoyii

Thunnus obesus
Bigeye tuna

Thunnus obesus

Thunnus obesus differs in having pectoral fins very long, extending beyond second dorsal fin, tips tapering to a thin flexible point (in adults) (vs. short, not reaching interdorsal space); a series of body markings as white/silver irregularly spaced, vertical, sometimes broken lines (vs. white/silver markings as vertical lines and alternating lines of spots, mostly confined to lower portion of body).

to Thunnus obesus

Thunnus tonggol
Longtail tuna

Thunnus tonggol

Thunnus tonggol differs in having pectoral fins that are moderate in length, not reaching to origin of second dorsal fin (vs. short, not reaching to interdorsal space); posterior portion of body (from deepest point to caudal peduncle) long relative to FL (vs. moderate); horizontal rows of white/silver elongate spots on belly (vs. white/silver markings as vertical lines and alternating lines of spots, mostly confined to lower portion of body) and ventral surface of liver not striated, right lobe elongate (vs. striated, lobes roughly equal in length).

to Thunnus tonggol
External links:

FishBase
The IUCN Red List of Threatened SpeciesTM

References:
  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. Tanaka Y, Satoh K, Iwahashi M, Yamada H. Growth-dependent recruitment of Pacific bluefin tuna Thunnus orientalis in the northwestern Pacific Ocean. Marine Ecology Progress Series. 2006;319:225–35.
  3. Collette BB, Cole K. Reproduction and development in epipelagic fishes. Reproduction and sexuality in marine fishes: patterns and processes University of California Press, Berkeley. 2010;21–63.
  4. Shimose T, Tanabe T, Chen K-S, Hsu C-C. Age determination and growth of Pacific bluefin tuna, Thunnus orientalis, off Japan and Taiwan. Fisheries Research. 2009;100(2):134–9.