Scientific name: |
Thunnus albacares |
Other names: |
Yellowfin, thon juane (France), Ahi, Shibi, kiwada (Japan) |
Yellowfin tuna is a worst choice tuna species. A better alternative is albacore or skipjack tuna.
Yellowfin tuna is a highly migratory species, found mainly in the warm ocean waters of northern New Zealand and moving south in summer to East Cape. Like many tuna, it is an important oceanic predator. They are caught in New Zealand as a bycatch in the northern bigeye and southern bluefin tuna longline fisheries, on the west and east coast of the North Island. The New Zealand catch is a very small part (0.03%) of the Pacific fishery, which is managed by the Western and Central Pacific Fisheries Commission (WCPFC).
Yellowfin tuna is caught in the tuna surface longline fishery. There are concerns about the absence of catch limits in the high seas fishery, the declining catch rates, the bycatch of sharks, seabirds New Zealand fur seals, and turtles in the fishery. The bigeye target tuna longline fishery captures turtles, including leatherback, a vulnerable threatened species. It also has an estimated capture of 593 seabirds a year, including vulnerable threatened Gibson’s and Antipodean albatross, and near-threatened southern Buller’s albatross. An estimated 623 seabirds a year are caught in the southern bluefin tuna target fishery, including white-capped albatross and Buller’s albatross. This fishery also catches about 100 fur seals annually and vulnerable shark species like porbeagle, mako and thresher sharks.
New Zealand fishery is not certified under any scheme.
The export value of yellowfin tuna was $268,000 in 2015, with about half being exported to Japan and other major markets in Thailand and Vietnam. The export value of all tuna and swordfish species combined was $42.3 million in 2015.
Asssessment output
No regional or fishing method difference.
| Score: | D |
| Population size: | Current spawning biomass is estimated to be “About as Likely as Not” to be at or above the lower end of the range of 40-60% of its unfished size. |
| Annual catch limit: | Limit set at 263 tonnes since 2004. |
| Recorded catch: | Latest reported annual landings of 1.4 tonnes in 2013-14 within the EEZ, and 199 tonnes by New Zealand flagged vessels fishing out of zone, which is minor compared to Western and Central Pacific catches of over 607,000 tonnes. |
| Stock trends: | Declining stock size, unlikely to be sustainable. Spawning biomass has reduced to 38% of unexploited stock size by 2012, with depletion to 31% in the central Pacific and to 24% in the Bismarck Sea to Solomon Sea area. |
| MSY Status: | The yellowfin stock is likely to be above BMSY. |
| The Ministry of Primary Industries assessment plenary report includes: | “Biomass has been reduced steadily over time reaching a level of about 38% of unexploited biomass in 2012. However, depletion is considerably higher in the equatorial [Pacific] region. Recent depletion levels are approximately 0.31 for spawning biomass (a 69% reduction from the unexploited level) and 0.24% in the [Bismarck Sea to Solomon Sea area].” “Recent recruitment is lower than the long average.” (MPI 2015, p530-532). |
| Score: | C |
| Distribution: | Yellowfin tuna are caught on the west coast and east coast of the North Island. |
| Maximum age (years): | 8+ |
| Age at sexual maturity: | 2 |
| Growth rate: | Medium |
| Reproductive output: | Medium |
| Age exploited: | 2 |
| Ability to recover: | Moderate |
| Score: | B |
| Fishing method(s): | Yellowfin tuna is caught as bycatch in North Island tuna fisheries. About 68% is caught by vessels targeting bigeye tuna with a smaller amount in other tuna fisheries. |
| Habitat damage: | No benthic impact |
| Habitat of particular significance: | Hasn’t been defined in New Zealand. |
| Bycatch: | Various sharks are caught in the longline fishery and, combined, make up over 90% of the bycatch by number. |
| Ecological effects: | Excessive removal of this large predator species can have considerable ecological implications. |
| Score: | E |
| Bycatch: | A number of other species are also caught in the tuna longline fisheries, including New Zealand fur seals, marine mammals, sharks, seabirds and turtles. The observed rate of turtle captures are one per year but, given level of observer coverage, actual numbers could be 10-40 times this. In the bigeye tuna fishery it is estimated that four New Zealand fur seal captures occur per year (based on the last 5 years), and an estimated 593 seabirds a year including vulnerable threatened Gibson’s and Antipodean albatross, and near-threatened southern Buller’s albatross (includes cryptic mortality). In the southern bluefin tuna fishery, an estimated 623 seabirds are caught, and an estimated 100 fur seals a year (based on the last 5 years). Vulnerable threatened sharks, like porbeagle, mako and thresher sharks are also caught. |
| Score: | A |
| Management component: | Single species |
| Score: | C |
| Quota Management Species: | Yes, since 2004. |
| Catch limits: | Yes for the New Zealand EEZ, but not in the high seas and Pacific fishery. |
| Management plan: | Highly Migratory Species management plan for 2010-15 is out of date, and has yet to be reviewed and replaced. There is no operational plan and the old management plan lacks key environmental standards. The National Plans of Action on Seabirds and Sharks are more relevant but they are slow to be implemented. There is no international management plan and the Western and Central Pacific Fisheries Commission (WCPFC) has yet to apply effective measures to prevent over-fishing. |
| Stock assessment: | A completed quantitative stock assessment for the Western and Central Pacific Conservation (WCPO) Fisheries Scientific Committee (2014), not updated. |
| Research: | There is very limited research on yellowfin tuna by New Zealand. |
| Observer coverage: | Observer coverage of 4.7% annually over the last 5 years. |
Fisheries map
Taken from the Ministry for Primary Industries’ Plenary report for fisheries management.
References
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