Scientific name: |
Katsuwonus pelamis |
Other names: |
skipjack, bonite (France), tunny (UK), katsuo (Japan) |
Skipjack tuna is the second most ecologically sustainable tuna species on the Best Fish Guide and is good to eat. If possible, try to avoid skipjack caught in association with catches of yellowfin and bigeye tuna, which are overfished.
This top predator is a highly migratory species of tuna found worldwide in tropical and subtropical waters, usually preferring the warmer surface waters. New Zealand is the southern limit of the skipjack tuna migration route (which is well known for being very long) where they visit the northeast from December to May, or in later months from New Plymouth to Cape Farewell. Skipjack are predominantly caught by purse seine vessels operating north of New Plymouth and Hawkes Bay. The New Zealand catch is a small part of the Pacific fishery, which is now managed by the Western and Central Pacific Fisheries Commission (WCPFC).
Skipjack tuna is caught mainly (97%) by purse seine. There are concerns over uncertainty about the state of the stocks, the bycatch of sharks, the bycatch of yellowfin and bigeye tuna in the Pacific fishery, plus the lack of a catch limits or a management plan. Bycatch includes mako sharks (a vulnerable threatened species), yellowfin tuna, sunfish, striped and blue marlin, the near-threatened spine-tailed devil rays and vulnerable threatened sharks like thresher shark. Other protected species observed caught in 2015 include three common dolphins and one loggerhead turtle.
Not certified under any scheme.
The main market is for canning outside New Zealand, primarily in Mauritius and Thailand. The export value of skipjack tuna was about $20.8 million in 2015. The export value of all tuna and swordfish species combined was $42.4 million in 2015.
Asssessment output
No regional or fishing method difference.
| Score: | B |
| Population size: | Unknown. South Pacific migratory population. |
| Annual catch limit: | It is not part of the quota management system (QMS) and no catch limits are set for New Zealand. |
| Recorded catch: | Latest reported annual landings in 2014 of 10,195 tonnes inside the New Zealand zone with another 9,141 tonnes caught by New Zealand flagged purse seine vessels on the high seas. This compares to 1,947,590 tonnes caught in the Western and Central Pacific in 2014. |
| Stock trends: | The stock assessment model was updated in 2014. The stock has declined to around 50% of unfished levels. |
| MSY Status: | Very likely to be above BMSY but latest catches exceed the MSY. |
| The Ministry of Primary Industries assessment plenary report includes: |
“Very Likely to be in the range 40-60% SB0”. “Biomass increased in the mid-1980s and fluctuated about the higher level over the subsequent period, before declining from 2008 to 2012. Recent depletion level is estimated at 0.52 (i.e. 0.48 of the unfished level). Projections indicated it is Exceptionally Unlikely that the [skipjack] stock would fall below the LRP level or that fishing mortality would increase above the FMSY level by 2032…” (MPI 2015, p413-417). |
| Score: | C |
| Distribution: | Skipjack tuna are caught on the west and east coasts of the North Islands, mainly north of New Plymouth and Hawkes Bay. |
| Maximum age (years): | 12? |
| Age at sexual maturity: | 1 |
| Growth rate: | Medium. |
| Reproductive output: | Medium |
| Age exploited: | 1 |
| Ability to recover: | Moderate |
| Score: | A |
| Fishing method(s): | Predominantly purse seine fishery around the North Island, from Hawkes Bay around North Cape to Taranaki, with less than 3% caught by troll or longline. |
| Habitat damage: | No benthic impact |
| Habitat of particular significance: | |
| Bycatch: | Skipjack are caught with over-fished small bigeye and yellowfin tuna in the purse seine fishery using Fish Aggregating Devices (FADs), which is a concern in the tropical Pacific fishery. Bycatch in New Zealand waters includes quota species jack mackerel, blue mackerel and yellowfin tuna. Non-QMS species include sunfish, striped and blue marlin, the near-threatened spine-tailed devil rays and other sharks. |
| Ecological effects: | Excessive removal of this large predator species can have considerable ecological implications. |
| Score: | C |
| Bycatch: | Purse seine fisheries have a residual risk of seabird bycatch. The near-threatened spine-tailed devil rays (CMS Appendix II), which is a protected species, is the fifth most common species caught in purse seine nets. Other protected species observed caught in 2015 include three common dolphins and one loggerhead turtle. |
| Score: | A |
| Management component: | Single species |
| Score: | D |
| Quota Management Species: | No |
| Catch limits: | No, nor is there a catch limit or Individual Transferable Quota (ITQ). |
| Management plan: | Highly Migratory Species management plan for 2010-15 is out of date, and has yet to be reviewed and replaced. There is a Skipjack operational plan for 2010-15, which is also now out of date and has yet to be reviewed and replaced, and the old plan and operational plans lack key environmental standards. 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 South Pacific assessment in 2011, revised in 2014 and 2016. |
| Research: | Some directed research by New Zealand on skipjack tuna, including characterisation and evaluation of distribution and abundance of skipjack tuna in New Zealand waters. |
| Observer coverage: | Coverage in the purse seine fishery has averaged around 9.9% over the last 5 years. |
Fisheries map
Taken from the Ministry for Primary Industries’ Plenary report for fisheries management.
References
Paste here.