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Striped marlin
Scientific name: |
Tetrapturus audax |
Other names: |
takaketonga (Maori), marlin |
Striped marlin is a worst choice fish. A better alternative is albacore or skipjack tuna.
Striped marlin is a highly migratory species of broadbill fish and an important oceanic predator. The management responsibility for this species, as with other Western Pacific migratory fish, lies with an international body – the Western and Central Pacific Fisheries Commission (WCPFC). However, the Ministry of Primary Industries is responsible for upholding WCPFC rules in New Zealand waters. Since 1987 there has either been a moratorium or equivalent measures on landing of any marlin species (striped, blue and black marlin) by commercial vessels between Mokau and East Cape (Auckland Fisheries Management Area) due to concerns about depleted stocks. In 2013 the arrangements were reviewed and the moratorium on commercial landings was extended. As a result of the agreement on billfish, striped marlin is principally a recreational-only fish (about 65% tagged and released to aid research).
Commercial captures of striped marlin are an incidental catch in the surface tuna longline fisheries. The concerns include uncertainty about the stock assessment plus the state of the stocks and catch limits. 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.
Not certified under any scheme.
Striped marlin is sold in East Asia.
Asssessment output
No regional or fishing method difference.
| Score: | D |
| Population size: | Unknown – South Pacific migratory population. |
| Annual catch limit: | None set. |
| Recorded catch: | Latest reported annual commercial catch of 19.8 tonnes in 2014, which were discarded, and 0 tonnes taken by New Zealand vessels outside the zone. |
| Stock trends: | Declining and likely to decline further without management intervention. |
| MSY Status: | The 2014 Assessment estimated the stock is below BMSY with the spawning biomass estimated at 24%Bo in 2011. |
| The Ministry of Primary Industries assessment plenary report includes: |
“Stock biomass declined rapidly through the 1960s, but the stock decline has been more gradual from 1970 through to 2011.” “Overall fishing mortality has shown a slow but continuous decrease since 2004.” “Recruitment is variable but has declined by 50% since the 1950s.” “The stock is likely to decline without management intervention.” (MPI, 2015, p468-479). |
| Score: | C |
| Distribution: | Striped marlin is caught mainly around the North Islands, north of 42⁰S. |
| Maximum age (years): | 12+ |
| Age at sexual maturity: | 1-2? |
| Growth rate: | Medium |
| Reproductive output: | Medium |
| Age exploited: | 2? |
| Ability to recover: | Moderate |
| Score: | B |
| Fishing method(s): | Striped marlin is caught as bycatch in tuna longline fisheries around the North Island, with 65% caught by vessels targeting bigeye tuna and 23% by southern bluefin tuna. |
| 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 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, including porbeagle, mako and thresher sharks, are also caught. |
| Score: | A |
| Management component: | Single species and one stock. |
| Score: | D |
| Quota Management Species: | No. Due to current arrangements marlin cannot be targeted by commercial fishers. |
| Catch limits: | |
| 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: | An initial stock assessment in 2012 by the WCPFC Scientific Committee, with collaboration by Australia and the Secretariat of the Pacific Community (SPC). |
| Research: | No targeted research apart from some tagging research on recreational catch. |
| Observer coverage: | Observer coverage of 4.7% annually over last 5 years. |
Fisheries map
Taken from the Ministry for Primary Industries’ Plenary report for fisheries management.
References
Paste here.