Pacific bluefin tuna
|Bluefin, Northern bluefin tuna (Australia), thon rouge de sud (Canada, France), minamimaguro (Japan)|
Pacific bluefin tuna is a worst choice tuna. A better alternative is albacore or skipjack tuna.
Pacific bluefin tuna is a very large, highly migratory species that can move thousands of kilometres in a year. It was previously known as Northern bluefin tuna in the Pacific, but the northern bluefin is actually a different species (T. thynnus) that grows much bigger and is a rare visitor to New Zealand. Pacific bluefin tuna are occasionally caught in New Zealand, in association with southern bluefin tuna (T. maccoyii), in longline fisheries off the West Coast of the South Island, around Northland and in the Bay of Plenty.
Pacific bluefin is caught in the tuna surface longline fisheries, including the southern bluefin tuna. There are concerns over the limited research, the state of stocks, current over-fishing, unclear international management across different Pacific tuna management agreements (Western and Central Pacific Fisheries Commission and IATTC) and the lack of a management plan. The bycatch of a range of shark species is also of concern, as is the removal of this important predatory species from oceanic food webs. Seabirds, turtles and New Zealand fur seals are caught in the surface longline fishery. An estimated 623 seabirds a year are caught in the southern bluefin tuna target fishery, including white-capped albatross and Buller’s albatross. An estimated 100 fur seals a year are caught in the longline tuna fisheries, mostly in the southern bluefin tuna fishery. This tuna is listed as a vulnerable threatened species on the IUCN Red List.
Not certified under any scheme.
Pacific bluefin tuna is exported mainly to Japan (over 90%) where it is highly prized for sashimi and sushi. Pacific bluefin exports were valued at $698,000 in 2015. The export value of all tuna and swordfish species combined was $42.3 million in 2015.
No regional or fishing method difference.
|Population size:||Very likely to be below 10%Bo – estimated to be below 6%. “Biomass is close to the lowest level ever experienced.” North and Central Pacific migratory population.|
|Annual catch limit:||Limit set at 116 tonnes since 2004.|
|Recorded catch:||Latest reported annual landings of 12.1 tonnes in 2015, compared to 18,600 tonnes taken in the Pacific.|
|Stock trends:||Results of short term stock projections suggest that, under recent levels of fishing, the spawning stock biomass will decline.|
|The Ministry of Primary Industries assessment plenary report includes:||
“Very Likely to be below the Hard Limit (10%Bo). “Overfishing is Very Likely to be occurring.” “Very likely [that] Current Catch or TACC causing Biomass to remain below or to decline below Limits.” (MPI, 2015, p246-250)
|Distribution:||Pacific bluefin tuna are caught on the west coast of the South Island, around Northland and in the Bay of Plenty.|
|Maximum age (years):||20+|
|Age at sexual maturity:||3-5|
|Ability to recover:||Moderate|
|Fishing method(s):||Pacific bluefin are caught mainly by surface longline vessels targeting tuna. About 57% of tuna are caught in the bigeye tuna surface longline fishery and 22% in the southern bluefin tuna surface longline fishery.|
|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.|
Tuna longline fisheries catch seabirds, turtles and New Zealand fur seals. Some of these longline fisheries also catch vulnerable turtles at an observed rate of about one per year but, given level of observer coverage, actual numbers could be 10-40 times this. Bigeye tuna fishery catches an estimated four New Zealand fur seals per year (based on the last 5 years). The bigeye tuna fishery also captures 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. This fishery also catches an estimated 100 fur seals a year (based on the last 5 years). These longline fisheries all catch significant shark bycatch which, combined, makes up over 90% of the bycatch number. These sharks include porbeagle, mako and blue, which are all listed as vulnerable threatened species.
|Management component:||Single species|
|Quota Management Species:||Yes, in 2004.|
|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:||No New Zealand quantitative stock assessment. There is an assessment by the International Scientific Committee for tuna and tuna-like species (ISC) in 2014 and in 2016 for the WCPFC Scientific Committee and the IATTC Scientific Committee.|
|Research:||There is no directed research in New Zealand on Pacific bluefin.|
|Observer coverage:||Observer coverage of 4.7% annually over last 5 years in the longline fishery, but it is not spatially or temporally representative of the fishing effort.|