|warehou hiriwa (Maori), spotted warehou|
Silver warehou is a worst choice seafood. A better alternative is trevally or terakihi.
Like the white warehou, silver warehou are a deeper ranging warehou species than blue warehou, living off the continental shelf edge and its upper slope. It is mostly caught from the Chatham Rise (their major spawning ground), Canterbury Bight, southeast of Stewart Island and the west coast of the South Island at depths of 200-800m.
Silver warehou are caught by trawlers mainly as bycatch in the hoki, squid, barracouta and jack mackerel fisheries. Concerns about this fishery include the absence of a monitoring survey method and subsequently no quantitative stock assessment, resulting in the unknown sustainability of current catch levels and limits, the lack of current or reference biomass estimates and the uncertainty about stock boundaries. Also of concern is the regular overfishing of current catch limits, and the lack of a management plan. Bottom trawling impacts on seabed habitats and communities is concerning, as is seabird, fur seal, and non-target fish bycatch associated the fisheries in which this species is caught.
Not certified under any scheme.
Export value of about $18.2 million in 2015, with the main market being Japan (about 50%), China and Russia.
No regional or fishing method difference.
|Population size:||Unknown. No estimates of reference or current absolute biomass are available.|
|Annual catch limit:||Limit set at 10,380 tonnes since 2003-04.|
|Recorded catch:||Reported landings of 10,730 tonnes in 2014-15 which includes overfishing (excess catch) of the catch limit in area 3 & 4 (east coast South Island, and Southland and sub-Antarctic fisheries) over the last 5 years.|
|Stock trends:||Unknown. “Neither the trawl survey nor the CPUE time series are currently suitable for monitoring the stocks or useful for stock assessments.” Stock structure is unknown.|
|The Ministry of Primary Industries assessment plenary report includes:||“No estimates of biomass are available.” “The sustainability of current TACCs and recent catch levels for these fish stocks is not known, and it is not known if they will allow the stocks to move towards a size that will support the maximum sustainable yield.” (MPI 2016, p 1229).|
|Distribution:||Found mainly on the Chatham Rise (with the major spawning area on the western Chatham Rise), outer Canterbury Bight, South Island west coast and the shelf south east of Stewart Island at depths of 200-800m.|
|Maximum age (years):||23|
|Age at sexual maturity:||3-4|
|Growth rate:||Relatively fast to mature.|
|Reproductive output:||Medium to very high|
|Ability to recover:||Moderate|
|Fishing method(s):||Silver warehou is primarily caught as a bycatch in hoki, arrow squid, barracouta and jack mackerel trawl fisheries.|
|Habitat damage:||Bottom trawling destroys sea floor species assemblages and fragile seamount habitats. It decimates black coral, lace corals, colourful sponge fields, long-lived bryozoans and many other invertebrate species. Bottom trawl impacts include habitat modification, loss of biodiversity, loss of benthic productivity, modification of important breeding and juvenile fish habitat. The trawl footprint area and contact areas vary, but the Snares Shelf area, the Auckland Islands shelf, West Coast South Island, and northwest and southwest Chatham Rise were identified as amongst the highest frequency trawled areas in the New Zealand zone.|
|Habitat of particular significance:||hasn’t been defined in New Zealand|
|Bycatch:||As silver warehou is caught in other target fisheries, it is associated with a wide range of non-target catch and non-target fish. (See hoki, arrow squid, barracouta and jack mackerel for more information.)|
|Ecological effects:||The combined effects of destroying seafloor habitats and seamount ecosystems, non-target fish bycatch and protected corals can have considerable ecological implications.|
|Bycatch:||As silver warehou is caught in other target fisheries, it is associated with a wide range of non-target catch, including marine mammals and seabirds. See hoki, arrow squid, barracouta and jack mackerel for more information.|
|Management component:||Single species, with uncertainty about stock boundaries and how many stocks exist in the EEZ. A further complication is that in some areas there is spawning in late winter and other areas in late spring-early summer.|
|Quota Management Species:||Yes, since 1986.|
|Management plan:||Deepwater management plan for 2010-15 is out of date, and has yet to be reviewed and replaced. Silver warehou is a bycatch species of hoki in 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.|
|Stock assessment:||No quantitative stock assessment.|
|Research:||There has been little directed research on silver warehou in the last 5 years.|
|Observer coverage:||Coverage is 23% in the target hoki fishery, 52% in squid; 8% in barracouta, and 38% in jack mackerel. The middle depth coverage is unlikely to be spatially or temporally representative of the fishing effort.|