Australia country information

Common names: Bluefin, SBT, Southern bluefin tuna
Occurrence: native
Salinity: marine
Abundance: common (usually seen) | Ref: Kailola, P.J., M.J. Williams, P.C. Stewart, R.E. Reichelt, A. McNee and C. Grieve, 1993
Importance: commercial | Ref: Kailola, P.J., M.J. Williams, P.C. Stewart, R.E. Reichelt, A. McNee and C. Grieve, 1993
Aquaculture: commercial | Ref: FAO, 1997
Regulations: restricted | Ref: Kailola, P.J., M.J. Williams, P.C. Stewart, R.E. Reichelt, A. McNee and C. Grieve, 1993
Uses: gamefish: yes;
Comments: Occurs in Western Australia, South Australia, Victoria, New South Wales, (southern Queensland) and Tasmania (Ref. 9563). Stock structure: Southern bluefin tuna have a single spawning area and are morphologically uniform; studies have shown that tagged fish disperse rapidly over long distances. These phenomena indicate that southern bluefin tuna form a single stock in the southern hemisphere (Ref. 30320). Commercial fishery: Australian and Japanese fleets fish for southern bluefin tuna in the Australian Fishing Zone, and elsewhere these tuna are or have been fished by Japanese, Taiwanese, New Zealand, Indonesian and Korean fleets (Ref. 30322). In Australian waters, southern bluefin tuna are caught with drifting longlines, pole-and-line, purse seines, by trolling and sometimes with rod-and-reel. Southern bluefin tuna were occasionally caught by trolling before the 1940s. Experimental canning was undertaken in 1936 at a small cannery in southern New South Wales and in 1939 at the cannery at Port Lincoln, South Australia. However, the fishery did not become commercial until the early to mid 1950s off New South Wales and mid 1950s off South Australia when pole-and-line techniques were introduced (Ref. 30320). Catches in these States steadily expanded during the 1960s, and were supplemented during the 1970s by a rapidly growing Western Australian pole-and-line fishery. Aerial spotting extended the efficiency of locating fish and the range of the New South Wales and South Australian activities during the 1960s. Purse seining was successfully introduced in these areas in the mid 1970s (earlier attempts in 1953 and 1966 were largely unsuccessful). An effective joint operation was developed, using a pole vessel to hold fish at the surface with live bait while a purse seine was set around both the fish and pole boat. Catches expanded quickly, with the greater proportion of the South Australian and New South Wales catches taken by this combined pole and purse seine technique. However, after a production peak of 21,500 t in 1982, the Australian surface fishery catches were rapidly reduced by the imposition, and progressive reduction, of catch quotas. In 1991, the southern bluefin tuna catch by domestic vessels was less than 3000 t with the surface fishery located almost entirely off South Australia. The Western Australian fishery, after peaking at just over 6000 t in 1982-83, declined because of the transfer of quota to South Australia. The New South Wales surface fishery, on the other hand, collapsed in the early 1980s, when the occurrence of surface schools first declined and then virtually ceased (Ref. 30319). During the late 1980s the developing New South Wales small vessel longline fishery began to take southern bluefin tuna. Commercial trolling for southern bluefin tuna and albacore (Thunnus alalunga) has recently started off the Tasmanian east coast. Quantities taken are small but the return to fishers is good because the southern bluefin tuna are air-freighted fresh chilled to the Japanese ‘sashimi’ (raw fish) market. Japanese fishing for southern bluefin tuna with drifting longlines first commenced on the spawning grounds, spread south to the region of the West Wind Drift, then eastwards and westwards. By the late 1960s their fishing grounds extended from eastern New Zealand in the east to the South Atlantic in the west (Ref. 30318). Production peaked at 78,000 t in 1961 but had declined to around 20,000-30,000 t by the end of the 1970s despite continually increasing longline effort. During the 1980s, the catch declined to 11,500 t, then to 6065 t as quotas were implemented. The main areas of the Australian Fishing Zone fished for southern bluefin tuna by Japanese longliners were the waters adjacent to southern New South Wales, southern Tasmania and the Great Australian Bight; but incidental catches were taken from most areas of the Zone where southern bluefin tuna are present. Access restraints have recently confined Japanese southern bluefin tuna longlining in the Australian Fishing Zone to the Tasmanian region. However, joint venture arrangements between the Australian and Japanese industries have resulted in a portion of the Australian quota now being longlined. The joint venture fishers have access to some of the areas closed to licensed Japanese longliners. Southern bluefin tuna become available to the Western Australian surface fishery when approximately 40 cm FL (when about 1 kg and 1-2 years old) and to the South Australian fishery when about 2 years old. In general, they are fished by the Japanese longliners from approximately 90 cm (when about 15 kg and 4 years old) (Ref. 30319), but longline operations in the Great Australian Bight take small quantities of younger fish as well. Initially, most of the surface catch was canned. Towards the end of the 1980s about 30% of the Australian catch was still landed whole for canning. Now, virtually all southern bluefin tuna are gilled and gutted then air-freighted fresh, or shipped frozen, for the Japanese ‘sashimi’ market. Southern bluefin tuna taken by Japanese longliners are killed, gilled and gutted and frozen (to minus 60°C) during voyages lasting up to 15 months. Recreational fishery: Southern bluefin tuna of 7-20 kg were common in recreational catches off southern New South Wales until surface schools virtually disappeared there in the early 1980s. The Eaglehawk Neck area off eastern Tasmania was similarly affected, but troll catches resumed after the mid 1980s. Recreational troll catches off western Victoria and south-eastern South Australia failed for much of the 1980s, but showed a small recovery at the end of the decade. In Western Australia between Perth and Albany, 1-7 kg southern bluefin tuna are taken in small quantities by anglers. The Game Fishing Association of Australia record for southern bluefin tuna is 126 kg. Resource status: Trilateral scientific meetings between Australia, Japan and New Zealand have been held each year since 1982. The major conclusion of all assessments has been that the parent stock has continuously declined since the 1950s, the decline becoming more rapid in the early 1980s. Scientists have progressively become more pessimistic about the capacity of the stock to maintain adequate recruitment of young fish into the fishery. The 11th trilateral scientific meeting, in October 1992 in Japan, again concluded that the parent stock is at historically low levels, so the risk of recruitment collapse and the potential for parental stock collapse is at least as high as it has ever been. The meeting could not predict with certainty whether stocks would recover or decline in future under current catch levels (Ref. 30322). On a positive note, however, indications are that abundance of the juvenile stock has increased since 1986, mainly as a result of the drastic reduction of surface fishing in recent years. Different interpretations of the 1992 assessment lead to different predictions of appropriate catch levels: that there is a very high probability that the stock will increase not only under current catch levels but also under slightly higher catch levels; or, that there is a significant possibility that the stock is already in the process of recruitment collapse. While southern bluefin tuna currently support a valuable fishery, the value could be far greater if spawning populations could be rebuilt and the recruitment of young fish to the fishery enhanced. Also Ref. 2334.
National Checklist:
Country Information: httpss://www.cia.gov/library/publications/resources/the-world-factbook/geos/as.html
National Fisheries Authority: https://www.csiro.au/
Occurrences: Occurrences Point map
Main Ref: Kailola, P.J., M.J. Williams, P.C. Stewart, R.E. Reichelt, A. McNee and C. Grieve, 1993
National Database:

Classification / Names

Actinopterygii (ray-finned fishes) > Perciformes (Perch-likes) > Scombridae (Mackerels, tunas, bonitos) > Scombrinae
Common names | Synonyms | Catalog of Fishes (gen., sp.) | ITIS | CoL

Common names from other countries

Thon rouge du sud, Atún rojo del Sur, SBT, ... more

Main reference

Collette, B.B. and C.E. Nauen. 1983. (Ref. 168)
References | Biblio | Coordinator : Collette, Bruce B. | Collaborators

Size / Weight / Age

Max length : 245 cm FL male/unsexed; (Ref. 5203); common length : 160 cm FL male/unsexed; (Ref. 9684); max. published weight: 260.0 kg (Ref. 5203); max. reported age: 20 years (Ref. 168)

Length at first maturity
L_m 119.0, range 120 - 130 cm

Environment

Marine; pelagic-oceanic; oceanodromous (Ref. 51243); depth range 50 - 2743 m (Ref. 57178)

Climate / Range

Temperate; 5°C - 20°C (Ref. 168), preferred 16°C (Ref. 107945); 8°S - 60°S, 180°W - 180°E (Ref. 54921)

Distribution

Atlantic, Indian and Pacific: temperate and cold seas, mainly between 30°S and 50°S, to nearly 60°S. During spawning, large fish migrate to tropical seas, off the west coast of Australia, up to 10°S. Highly migratory species, Annex I of the 1982 Convention on the Law of the Sea (Ref. 26139). If the current exploitation continues, the population will be below 500 mature individuals in 100 years (Ref. 27905).
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Short description

Vertebrae: 39. A very large species, deepest near the middle of the first dorsal fin base. Swim bladder present. Lower sides and belly silvery white with colorless transverse lines alternating with rows of colorless dots. The first dorsal fin is yellow or bluish; the anal fin and finlets are dusky yellow edged with black; the median caudal keel is yellow in adults.

By maturity, most southern bluefin tuna lead an oceanic, pelagic existence (Ref. 6390). Spawning fish and larvae are encountered in waters with surface temperatures between 20° and 30°C. An opportunistic feeder, preying on a wide variety of fishes, crustaceans, cephalopods, salps, and other marine animals. Mostly canned (Ref. 9684). A specialized fishery for sashimi-quality has been developed recently by New Zealand fishers. In Japan, it is highly prized for the sashimi markets.

IUCN Red List Status (Ref. 115185)

Critically Endangered (CR) (A2bd)

Threat to humans

Harmless

Human uses

Fisheries: commercial; aquaculture: commercial; gamefish: yes

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Estimates of some properties based on models

Phylogenetic diversity index (Ref. 82805)
PD₅₀ = 0.5039 many relatives (e.g. carps) 0.5 - 2.0 few relatives (e.g. lungfishes)

Trophic Level (Ref. 69278)
3.9 ±0.53 se; Based on food items.

Resilience (Ref. 69278)
Low, minimum population doubling time 4.5 - 14 years (K=0.14-0.15; tm=8-9; tmax=20; Fec=14 million)

Vulnerability (Ref. 59153)
High to very high vulnerability (67 of 100)

Price category (Ref. 80766)
Very high

Thunnus maccoyii (Castelnau, 1872)