Tuna, southern bluefin (Caught at sea)

Thunnus maccoyii

Method of production — Caught at sea
Capture method — All applicable methods
Capture area — Worldwide (FAO All Areas)
Stock area — Southern Hemisphere
Stock detail

All Areas


Picture of Tuna, southern bluefin (Caught at sea)

Sustainability rating five info

Sustainability overview

Southern bluefin tuna have a low resilience to fishing pressure due to their longevity and late size at maturity. This is an extremely valuable species, with individual fish worth tens of thousands of pounds, which has led to heavy overfishing in the past. It is assessed as Critically Endangered by IUCN (International Union for the Conservation of Nature). In 2011 the biomass of the spawning stock was estimated to be 5% of unfished levels. Despite recent improvements in management seeing the spawning stock increase to 13%, it is still well below safe levels. The fishery overlaps with a number of endangered and critically endangered seabirds, notably albatross and petrel, which are caught as bycatch, especially in longline fisheries. The impact of the fishery on sharks is not well understood. In 2016, most of the southern bluefin catches were made by longline (62%) and purse seine (38%).

Biology

Tuna belong to the family Scombridae. They are large, oceanic fish and are seasonally migratory, some making trans-oceanic journeys. Southern bluefin are found in temperate and cold seas of the southern hemisphere, but migrate to the tropics to spawn. They are a very large species, growing to 245cm in length and 260kg in weight, with a maximum age of 40 years. Southern bluefin mature between 8 -11 years of age (about 155cm in length). Young fish migrate seasonally between the south coast of Australia and the Indian Ocean. The only known spawning ground is in an area south-east of Java, Indonesia.

Stock information

Criterion score: Default red rating info

Stock Area

Southern Hemisphere

Stock information

The Southern bluefin tuna stock (SBT) is assessed and managed by the Commission for the Conservation of Southern Bluefin Tuna (CCSBT). This stock has been exploited for more than 50 years, with total catches peaking at 81,750 t in 1961. A 2006 review of data by the Commission indicated that catches during the preceding 10 to 20 years may have been substantially under-reported. A new stock assessment was carried out in 2017 and suggested that the spawning biomass was only 13% of its unfished state. However, this is an improvement on previous years: assessments indicated the stock was at 5% of its original biomass in 2011 and 9% in 2014. The fishing mortality rate is below the level associated with MSY (F at 0.5FMSY) but the stock remains in a much overfished state (Spawning Stock Biomass, SSB, is 0.49 of SSB MSY). Provisional 2017 catch is 13,947 t, similar to the 2016 catch of 14,445 t. The interim rebuilding objective, set in 2011, is to reach 20% of the unfished state by 2035 with 70% probability, and there is a limit below which the stock size should not be allowed to fall (SSB2010). There is a recent upward trend in the adult population which is a positive signal of rebuilding, recent recruitment is above the expected level (although more data is needed to model this accurately), and current levels of fishing mortality suggest future rebuilding will be faster than initially envisaged in 2011. There are suggestions that some relatively strong cohorts are moving through the fishery, though they have yet to contribute to the spawning stock.

Southern bluefin tuna remains Critically Endangered on the IUCN Red List.

Management

Criterion score: Default red rating info

While southern bluefin ranges throughout the southern Atlantic, Pacific and Indian Oceans, the Regional Fisheries Management Organisations (RFMOs) for these oceans essentially defer management of the southern bluefin stock to the Commission for the Conservation of Southern Bluefin Tuna (CCSBT). Roughly 60% of the catch is made in the Indian Ocean, 28% in the Pacific Ocean and 12% in the Atlantic Ocean. Owing to its high value, the stock has been considerably overfished and considerable under reporting of catches is thought to have occurred between 1986 and 2006.

The primary conservation measure for management of the southern bluefin tuna stock is the Total Allowable Catch (TAC), allocated across Japan, Australia, Republic of Korea, the Fishing Entity of Taiwan, New Zealand, Indonesia, European Union and South Africa. Some flexibility is provided for limited carry-forward of unfished allocations between quota years. In recent years, reported catches have been below the TACs (which are set at 14,647t for 2015-2017, increasing to 17,647t for 2018-2020). These TACs are set in accordance with the long term management plan for the fishery, which aims to recover stocks to 20% of their unfished level by 2035 with 70% probability. 2017 projections suggest this might be achieved sooner, however there are concerns over levels of unaccounted mortality, e.g. through IUU, and there is no long term rebuilding target. While the scientific committee suggests that the current management plan does not need to be changed, in 2017 they recommended as a matter of urgency to take steps to quantify all sources of unaccounted mortality. A new management procedure will be developed to guide the setting of TACs for 2021 and onwards, taking into account changes in data availability.

The CCSBT has a Catch Documentation Scheme (CDS) for southern bluefin tuna, providing for tracking and validation of legitimate products from catch to the point of first sale on domestic or export markets. All southern bluefin tuna products must be accompanied by documentation which includes details of the vessel and area of catch, which will help monitor catches and trade. In addition, the CCSBT have developed a register of vessels that are authorized to catch southern bluefin tuna, so that members and cooperating non-members of the CCSBT are required to refuse the import of this species caught by vessels not on the list, as well as an annually-reviewed register of vessels carrying out Illegal, Unreported and Unregulated (IUU) fishing. All transhipments must be authorised in advance and Observed. In 2016, the Commission banned the use of large-scale driftnets on the high seas where it might lead to catches of southern bluefin tuna.

As the fishery operates within the jurisdiction of other RFMOs, vessels are also expected to adhere to the management and conservation measures of these intergovernmental organisations. CCSBT works to ensure its own regulations are compatible with those of other RFMOs.

Capture Information

Criterion score: Default red rating info

In 2016, most of the southern bluefin catches were made by longline (62%) and purse seine (38%). 60% of the catch was made in the Indian Ocean, 28% in the Pacific and 12% in the Atlantic. Current catches are around 18% of what they were at their peak in 1961.

Pelagic longlining targets large, mature fish, but encounters a relatively high proportion of bycatch of vulnerable species including large sharks, seabirds, marine turtles and other tuna and billfish. There is only one binding CCSBT measure relating to bycatch mitigation, which is to reduce seabird bycatch by requiring that Tori poles be used in all longline fisheries below 30 degrees south. There are other non-binding measures, and in 2018 CCSBT passed a resolution to align its measures with the measures of other RFMOs, although those measures can be inconsistent from one RFMO to the next and don’t necessarily follow best practice. Furthermore, the ability of CCSBT to enforce compliance is weak. Bycatch of seabirds is of serious concern, having remained high for several years, but a proposed binding resolution in 2017 could not be agreed upon. There are also concerns that there is not enough data to determine whether sharks also need better protection through additional bycatch mitigation measures - there is no fixed list of shark species affected by this fishery, preventing stock assessments from being carried out.

The purse seine component of the catch is usually made on younger fish which are then slowly towed in large net pens back to the coast. Here, they are fattened for later sale on the sashimi market and individual fish can fetch upwards of GBP 100,000.

There is a ban on the use of large-scale driftnets on the High Seas in a manner which can reasonably be expected to result in the catching, taking or harvesting of southern bluefin tuna. In 2017 CCSBT agreed to examine standards for electronic monitoring programs on vessels fishing for southern bluefin, to support observer programmes. There is a target level of 10% observer coverage of catch and effort, but compliance with this is patchy and it has been suggested that a target of 20% on longliners would be more appropriate.

Alternatives

Based on method of production, fish type, and consumer rating: only fish rated 2 and below are included as an alternative in the list below. Click on a name to show the sustainable options available.

Anchovy, anchovies
Arctic char
Herring or sild
Salmon, Atlantic (Farmed)
Salmon, Chinook, King Salmon
Salmon, Chum, Keta, Calico or Dog salmon
Salmon, Coho , Silver, White
Salmon, Pink, Spring , humpback
Salmon, Sockeye , Red Salmon, Bluebacks, Redfish
Sprat, whitebait
Swordfish
Trout, Rainbow
Tuna, albacore
Tuna, bigeye
Tuna, skipjack
Tuna, yellowfin

References

CCSBT, 2017. Report of The Twelfth Meeting of the Ecologically Related Species Working Group for the Commission for the Conservation of Southern Bluefin Tuna, 21-24 March 2017, Wellington, New Zealand. 42 pp. Available at https://www.ccsbt.org/en/content/reports-past-meetings [Accessed on 10.12.2018].

CCSBT, 2018. Report of the Twenty Fifth Annual Meeting of the Commission for the Conservation of Southern Bluefin Tuna, 18 October 2018, Noumea, New Caledonia, 95 pp. Available at https://www.ccsbt.org/en/content/reports-past-meetings [Accessed on 04.12.2018].

CCSBT, 2018. Report of the Twenty Third Meeting of the Scientific Committee of the Commission for the Conservation of Southern Bluefin Tuna, 8 September 2018, San Sebastian, Spain, 95 pp. Available at https://www.ccsbt.org/en/content/reports-past-meetings [Accessed on 04.12.2018].

Collette, B., Chang, S.-K., Di Natale, A., Fox, W., Juan Jorda, M., Miyabe, N., Nelson, R., Uozumi, Y., Wang, S., 2011. Thunnus maccoyii. The IUCN Red List of Threatened Species 2011: e.T21858A9328286. Available at http://dx.doi.org/10.2305/IUCN.UK.2011-2.RLTS.T21858A9328286.en [Accessed on 10.12.2018].

ISSF, 2018. Status of the world fisheries for tuna: October 2018. ISSF Technical Report 2018-21. International Seafood Sustainability Foundation, Washington, D.C., USA. 103 pp. Available at: https://iss-foundation.org/about-tuna/status-of-the-stocks/ [Accessed on 06.12.2018].