Warehouse hiriwa, Spotted Warehou
Silver warehou are common around the South Island and on the Chatham Rise in depths of 200–800 m. The majority of the commercial catch is taken from the Chatham Rise, Canterbury Bight, southeast of Stewart Island, and the west coast of the South Island.
Silver warehou is managed by Fisheries New Zealand (FNZ) and has been part of the Quota Management System (QMS) since 1986. FNZ works in partnership with Deepwater Group (a not for profit organisation that works on behalf of fisheries quota owners) to manage and monitor various aspects of the fishery.
There are no current recreational fisheries for silver warehou.
The risk assessment covers roughly 85% of all silver warehou caught in New Zealand.
For more information, download the full Risk Assessment Report.
The risk assessment framework is used to assess the relative environmental risks of Australian and New Zealand wild-caught fisheries on fish stocks and the aquatic environment.
Assessments are undertaken for each species according to multiple ‘units of assessment’ (UoAs). The UoA is a combination of target species/stock and the gear type used by the fishery. Each UoA is assessed against three components for target species, bycatch and ecosystems, and management systems. Each component has a number of performance indicators, which have associated criteria, scoring issues, and scoring guideposts. For each UoA, each performance indicator is assigned a risk score according to how well the fishery performs against the scoring guideposts. The summary of risk scores by UoA is presented in the table below.
An assessment of the future ‘outlook’ over the short to medium-term (0-3 years) is provided against each component. Outlook scores are provided for information only and do not influence current or future risk scoring.
All risk assessments are conducted by an independent third party. The process only takes a few days and includes opportunities for management groups and the government to provide input and peer review.
The information presented on this page is extracted from the independent species Risk Assessment Report.
Risk Assessment Summary
Component 1 of the risk assessment looks at the health of the population of target species including the current fishing effort and estimates a risk of overfishing.
No estimates of silver warehou biomass are available and the status of the stocks is unknown. There are no stock assessments available for any silver warehou stocks. Neither the trawl survey nor the catch per unit effort (CPUE) time series is currently suitable for monitoring the stocks or useful for stock assessments. While commercial removals from the fishery are closely monitored through the QMS reporting arrangements, with validation from observers, there is no reliable index of abundance available at this stage.
In most years from 2000–01 to 2008–09, catches in SWA 3 and SWA 4 were well above the Total Allowable Commercial Catch (TACC) as fishers landed catches well in excess of Annual Catch Entitlement (ACE) holdings. 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.
The harvest strategy in the commercial silver warehou fisheries consists of:
- Catch controls through Total Allowable Catches and Individual Transferable Quotas;
- Disincentives to over-catch through the application of deemed values;
- Gear restrictions;
- Monitoring through logbooks and catch returns;
- Monitoring through Vessel Monitoring Systems;
- Periodic review of stock status and recommended Total Allowable Catch levels through the government Working Group process.
Bycatch and ecosystems
Component 2 of the risk assessment looks at the risks around bycatch species and other environmental impacts of the fishery.
Silver warehou is taken in targeted trawls, as well as trawls targeted at other species (e.g. hoki, barracouta, hake). While information to evaluate the total catch composition of trawls taking silver warehou is complicated because it is frequently taken as a bycatch in other targeted fisheries in SWA 3, sufficient information appears to be available to determine the impacts on likely main other species with respect to status and to detect increased risk to them. The main limitation appears to be a lack of detailed information on full catch composition, including discards. In SWA 4, very good quantitative information is available for some species (hoki, hake) and is sufficient to detect the impact of the fishery with respect to status. For BAR 4, quantitative information is available, however, the fishery has been highly variable and no standardised analysis is possible.
There is limited information on endangered, threatened and protected (ETP) species interactions specific to silver warehou targeted trawls, although it is taken in the same depth range and at the same time as hoki, hake and barracouta targeted trawls so we have assumed ETP species interactions and risks will be similar to these fisheries. On that basis, the main potential ETP species interactions are likely to be with seabirds, marine mammals, and protected corals.
It appears highly likely that current rates of capture are not hindering the recovery of marine mammal species or protected corals. The existing seabird mitigation strategies also appear likely to ensure the trawl fishery does not hinder the recovery of seabird species.
Component 3 of the risk assessment looks at the risks around the management systems of a fishery.
The Fisheries Act 1996 (the Act) and subsequent amendments provide a binding legislative and legal framework for delivering the objectives of Components 1 and 2. Sections 10, 11, and 12 of the Act establish the requirements for the decision-making process, and Section 10 further requires the use of the best available information for all decisions. This results in measures and strategies to achieve the fishery-specific objectives. The Act requirement for best available information leads to scientific evaluation in advance of decisions. The Act further requires consultation with such persons or organisations as the Minister considers are representative of those classes of persons having an interest in the stock or the effects of fishing on the aquatic environment in the area concerned including Maori, environmental, commercial, and recreational interests.
The management system relevant to silver warehou has explicit short and long-term objectives which are set out in long-term plans e.g., Fisheries 2030, National Fisheries Plan, and Annual Operational Plans. Objectives are subject to an annual review report and are explicit within the fishery’s management system.
Summary of main issues
Main issues highlighted by the assessment are:
- The stock structure of silver warehou is not known.
- There are no stock assessments available for any silver warehou stocks. No estimates of biomass are available and the status of the stocks is unknown. The sustainability of current TACCs and recent catch levels for SWA 3 and SWA 4 is not known.
The outlook below provides a qualitative judgment about the likely future performance of the fishery against the relevant risk assessment criteria over the short to medium-term (0-3 years). Assessments are based on the available information for the species and take into account any known management changes.
- Target species - Uncertain: McGregor (2016) outlines a range of work that could be undertaken to make CPUE data more reliable as an indicator of stock abundance, although it is not known when the work will occur.
- Bycatch and ecosystems - Stable: No major changes to existing bycatch and ecosystem arrangements are expected.
- Management systems - Stable: No major changes to existing management system arrangements are expected.