Scientific name: |
Scomber australasicus |
Other names: |
tawatawa, tewetewe (Maori), English mackerel, Pacific mackerel, southern mackerel, maquereau (France), saba (Japan) |
Blue mackerel (English mackerel) caught using purse seine from the North Island’s east coast from Cape Reinga to East Cape is the best choice. Trawl-caught mackerel from the west coast of the North and South Island is a worst choice fish and should be avoided. An alternative is skipjack tuna.
Blue mackerel (English mackerel) is a relative of tuna and is similarly widely distributed around the Pacific, including New Zealand. It is often found below schools of jack mackerel and kahawai and is caught year round, primarily by purse seine fishing. Some blue mackerel is also trawl caught.
Blue mackerel are caught primarily using purse seine nets (northern North Island) or bottom trawls. Concerns include the little-known state of fish stocks, the unknown sustainability of catch levels, declining catch rates on the West Coast, limited research and the lack of a management plan. Also of concern are the bycatch of dolphins and other fish species and the impacts of bottom trawling.
Not certified under any scheme.
Exports worth about $10.5 million in 2015. Main markets are Australia (25%), Fiji (20%); Philippines (20%) then Russia and the Ivory Coast.
Asssessment output
Blue mackerel was assessed for differences between purse seine and trawl caught fish. Regional differences were also assessed. Purse seine blue mackerel caught from the North Island’s east coast from Cape Reinga to East Cape were ranked amber, a good seafood choice. Trawl caught blue mackerel ranked red, a worst choice which should be avoided.
| Score: | Both purse seine and trawl – D |
| Population size: | Unknown but thought to be moderate size. |
| Annual catch limit: | Limit set at 11,550 tonnes since 2001-02. |
| Recorded catch: | Reported landings of 9,129 tonnes in 2014-15. |
| Stock trends: | Unknown. However, large decline in catch rates in EMA 7 (west coast of both islands) which may indicate a decline in abundance. Catch sampling in 2004-05 also noted relatively low numbers of small fish. |
| MSY Status: | Unknown. No estimates of biomass are available. |
| The Ministry of Primary Industries assessment plenary report includes: | “Little is known about the status of blue mackerel stocks and no estimates of current and reference biomass, or yield, are available for any blue mackerel area. It is not known if recent catch levels are sustainable or at levels that will allow the stocks to move towards a size that will support the MSY.” (MPI 2016, p 177). |
| Score: | Both purse seine and trawl – C |
| Distribution: | Pelagic species, widespread around the North Island and northern South Island. |
| Maximum age (years): | 24+ |
| Age at sexual maturity: | 2 |
| Growth rate: | Moderate |
| Reproductive output: | Medium to high |
| Age exploited: | 3 |
| Ability to recover: | Moderate |
| Score: | Purse seine – A, trawl – E |
| Fishing method(s): | Mainly purse-seining in QMA 1 (east coast of the North Island between Cape Reinga to East Cape) while in QMA 7 (west coast both islands) most is caught as bycatch in the jack mackerel fishery. |
| Habitat damage: |
Purse seine: Low Trawl caught:Impacts include loss of biodiversity, loss of benthic productivity and modification of important habitat like breeding or juvenile areas. |
| Habitat of particular significance: | for blue mackerel hasn’t been defined in New Zealand. |
| Bycatch: | Caught in association with other pelagic species including jack mackerel, kahawai, skipjack tuna and trevally. |
| Ecological effects: | This fishery has an impact on a range of pelagic fish species, which play an important role in driving smaller baitfish species close to the sea surface where a variety of seabird species are able to feed on them. Reducing these pelagic fish species can in turn reduce the amount of baitfish available at the sea surface for seabirds to feed on. |
| Score: | Purse seine – B, trawl – E |
| Bycatch: |
Purse seine: May have low numbers of protected species bycatch. Trawl: When caught with the jack mackerel fishery, there is a common dolphin bycatch on the West Coast of the North Island. Inshore trawl fisheries have an estimated seabird bycatch of 4370 seabirds (this includes cryptic mortality of birds that strike the trawl warps and are not recovered in the nets). Species reported include white-capped albatross, Salvin’s albatross and white-chinned petrels. Fur seal captures have also been estimated in the inshore trawl fisheries at about 20 per year. |
| Score: | Both purse seine and trawl – C |
| Management component: | Single species |
| Score: | Both purse seine and trawl – C |
| Quota Management Species: | Yes, since 2002. |
| Catch limits: | Yes |
| Management plan: | Deepwater management plan for 2010-15 is out of date, and has yet to be reviewed and replaced. Mackerel is outside of the current plan and only areas QMA 3 and 7 would be considered. There is no operational plan and the old Deepwater plan lacks key environmental standards. The National Plans of Action on Seabirds and Sharks are more relevant to bycatch issues but they are slow to be implemented. There is no inshore plan to cover QMAs 1 and 2. |
| Stock assessment: | No quantitative stock assessment. |
| Research: | There is little directed research on blue or English mackerel. |
| Observer coverage: | Unobserved in QMA1 but about 38% of the trawl effort for jack mackerel which catches blue mackerel is observed. Unlikely to be spatially or temporally representative of the fishing effort. |
Fisheries map
Taken from the Ministry for Primary Industries’ Plenary report for fisheries management.
References
Report from the Fishery Assessment Plenary, May 2016: stock assessments and yield estimates. Part 1: Introductory Section to Hoki, Science Group, Ministry for Primary Industries; Ministry for Primary Industries (2016) Aquatic Environment and Biodiversity Annual Review 2015. Compiled by the Fisheries Management Science Team, Ministry for Primary Industries. 682p. The Guidebook to New Zealand Commercial Fish Species, 2007 Revised Edition, The New Zealand Seafood Industry Council Ltd. Seafood New Zealand, 2016. New Zealand Seafood Exports to December 2015. 133p. Annual Review Report for Deepwater Fisheries for 2014/15. MPI Technical Paper No: 2016/09. Prepared by the Ministry for Primary Industries. March 2016. 103p. S.J. Baird, D. Tracey, S. Mormede, M. Clark (2013) The distribution of protected corals in New Zealand waters. Prepared for DOC, February 2013. 96p. MFish (2010) National Fisheries Plan for Deep-Water and Middle-Depth Fisheries, 2010. 51p.