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Gemfish

Scientific name:

Rexea solandri

Other names:

maha-taharaki, maka-tikati, tiikati (Maori), silver kingfish, southern kingfish, silver gemfish (US), kagokamasu, ginsawara, shirosawara (Japan)

Ranking

Best or alternative choice

Gemfish caught anywhere in New Zealand is a worst choice seafood. A better alternative is kingfish.

Description

This relatively long-lived slender fish is found in a wide depth range of between 50 and 550m, but is sometimes found as deep as 800m. They are usually caught from inshore to middle-depth waters by trawling.

Ecological concerns

Gemfish are caught by bottom trawling. A significant level of habitat and therefore ecological damage is caused by bottom trawling and a range of fish is caught as bycatch. New Zealand fur seal and sea bird bycatch is also associated with fisheries in which gemfish is caught as bycatch. Annual catches and catch rates have declined dramatically since peaking at over 8,000 tonnes in 1985-86, due to over-fishing combined with low recruitment, poor state of the stocks (about 22% of the original, unfished stock size) and annual landings being in the hundreds of tonnes during the last ten years. There is also no management plan for this species.

Certification

Not certified under any scheme.

Economic value

Exports of $1.054 million in 2015 mainly to Japan (75%), Australia and Lithuania.

Asssessment output

Regional and or fishing method differences

Regional (stock) differences between the northern (SKI 1 and 2) and southern (SKI 3 and 7) fisheries were compared and assessed. While the northern caught gemfish ranked slightly higher than southern caught, both ranked red and are a worst choice seafood which should be avoided.

Status of seafood stocks - sustainability of catches

Score:  All regions – D
Population size:  For northern stock the 2007 biomass was estimated at around 22% of the unfished biomass, which is well below BMSY (34%) or the target of 40%Bo.
Annual catch limit:  Limit set at 1060 tonnes since 2001-02.
Recorded catch:  Reported landings were 503 tonnes in 2014-15, the lowest catch in over 30 years.
Stock trends:  Biomass for both stocks declined since the early 1990s, however some recovery may have occurred since then. There has been low recruitment since the early 1990s, with only one strong year class in 1991. This, combined with fishing, has resulted in depleted populations that could decline further if low recruitment continues.
MSY Status:  Populations are depleted, and there is no rebuilding plan in place.
The Ministry of Primary Industries assessment plenary report includes:

Southern gemfish: “The assessment of the southern gemfish stock has not been updated since 1997. Landings from SKI 7 increased from 2000 to be a level over twice the TACC in 2004-05, but have decreased since then.”

Northern gemfish: For all three models: B2006 wasestimated at between 22% and 32%. “With catches at the current TACC the stock is projected to increase if recruitment returns to the [long term] 1978 to 2000 average level, but decline slightly if recent (1992-2000) recruitment continues.” (MPI 2016, p 388-391).

Biological characteristics - risk of overfishing and ability to recover

Score:  All regions – D
Distribution:  Gemfish is found throughout New Zealand coastal waters but is more common in the south at depths of 150-200m.
Maximum age (years):  17
Age at sexual maturity:  3-6
Growth rate:  Moderate
Reproductive output:  Medium to high
Age exploited:  3-5
Ability to recover:  Low to moderate

Fishing method impacts including non-threatened species bycatch & habitat damage

Score:  All regions – E
Fishing method(s):  Gemfish is caught in a target bottom trawl fishery off the east and north coasts of the North Island. Catches off the west and southern coasts of the South Island are now primarily bycatch from the hoki and squid fisheries.
Habitat damage:

Inshore: after scampi, gemfish trawling had the highest impact of target fisheries in the Bay of Plenty (Cryer et al, 2002).

Deepwater: Bottom trawling within hoki and squid fisheries results in considerable damage to seafloor communities when caught by bottom trawl or midwater trawl which touches the bottom. Impacts include habitat modification, loss of biodiversity, loss of benthic productivity and modification of important breeding and juvenile fish habitat.

Habitat of particular significance:  hasn’t been defined in New Zealand.
Bycatch:  A range of fish including deepwater sharks and benthic species like coral, sponges and invertebrates are caught in the targeted fishery, including hoki, terakihi, silver warehou and bluenose.
Ecological effects:  The combined effects of destroying seafloor habitats and seamount ecosystems, non-target fish bycatch and protected corals can have considerable ecological implications.

Protected species or threatened species bycatch

Score:  All regions – E
Bycatch:

Seabird, fur seal and deepwater shark bycatch is associated with gemfish caught in the hoki and arrow squid fisheries.

Inshore: 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. The flatfish fishery has an estimated 928 annual seabird mortalities, including cryptic mortality. Fur seal captures have also been estimated in the inshore trawl fisheries at about 20 per year.

Hoki trawl: An estimated 192 fur seals are captured in the hoki fishery (5-year average). Based on the recent catch spread of hoki the main captures occurs in the Cook Strait (54%), off West Coast of the South Island (24%), off east coast of the South Island and Chatham Rise (15%). The hoki fishery catches about half of the estimated fur seals caught by trawling. The sub-Antarctic and Snares shelf hoki fishery has a low capture rate for nationally critical New Zealand sea lions of about one a year. The trawl fishery also captures about 1420 seabirds a year (5-year average): the main species are Salvin’s albatross, southern Buller’s albatross, white-capped albatross, sooty shearwater, white-chinned petrel, and cape petrels. Protected coral species are also reported caught in hoki tows in most quota areas. The corals caught include gorgonian, hydrocorals, black corals (Antipatharia) and stony corals (Scleractinia) – which includes reef-like, tree-like, and solitary small corals.Other bycatch species include vulnerable deepwater sharks (e.g. shovelnose dogfish, seal shark and Baxter’s dogfish). These low productivity species also include threatened basking sharks (observed at one per year, but could be higher), deepsea skates and some other elasmobranchs.

Unit of seafood stock arrangement

Score:  All regions – B
Management component:  Single species with at least two stocks. It is unclear whether west coast North Island is a different stock to east coast North Island.

Effectiveness of management, monitoring, & research

Score:  Northern region (SKI 1 & 2) – C, southern region (SKI 3 & 7) – E
Quota Management Species:  Yes, since 1986.
Catch limits:  Yes
Management plan:  Deepwater management plan for 2010-15 is out of date, and has yet to be reviewed and replaced. Gemfish in southern stock (QMA 3 and 7) are outside of the current plan. 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 approved inshore plan for northern gemfish (QMA 1 & 2).
Stock assessment:  Quantitative stock assessment for QMA1 and 2 in 2008, an updated CPUE in 2014, and QMA3 and 7 in 1997.
Research:  There has been no recent research in the southern fishery for nearly 20 years. The northern fishery had a full assessment in 2008.
Observer coverage:  Observer coverage is 27.3% in the hoki target fishery and 52% in the squid fishery. Observer coverage in the northern inshore fishery is less than 1.5%. The inshore fishery coverage is 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.  Cryer M, Hartill B and O’Shea S (2002). Modification of marine benthos by trawling: toward a generalization for the deep ocean?  Ecological Applications 12(6), 2002 pp1824-1839. 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.

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