Hake 2012 - Seafish

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2 Responsible Sourcing Guide: Hake. Version 6 – March 2012 Status of hake stocks March 2012 Biology Hake feed mainly on fish and squid, and may also feed on smaller hake, which is important in their stock dynamics. They tend to be slow-growing and late maturing, which makes them prone to overfishing. Most hake species show large vertical movements from near the sea bed, where they spend the day, into mid and surface waters at night to feed. Hake also show substantial offshore and along-shore migrations, a characteristic that is reflected in the large areas used for stock assessment and management (7). Fisheries and fishing methods Most hake are taken by bottom trawling, although pelagic trawls are also used in some areas. There are also a number of line and gill-net fisheries that target larger hake, especially in areas of rough (untrawlable) ground in the UK, Spain, Namibian and South African fisheries. Research Research on European hake is conducted by a number of European fisheries institutes under the auspices of ICES. Specific topics funded under recovery plans include improving mesh selectivity in trawls to conserve juvenile fish, and the identity and characteristics of the northern and southern stocks. The results of research on hake in South Africa and Namibia quickly feed through to management action supported by the industry in both countries. The Benguela Current Large Marine Ecosystem Programme is a multinational, ecosystem-based research initiative. There is also collaborative research with overseas institutes, notably Norway’s Institute of Marine Research through the Nansen Programme. Much is known about the Argentine hake and its fishery, with information being provided by a vessel monitoring system and a small, intermittent, observer programme. INIDEP operates a number of research vessels within the Argentine Exclusive Economic Zone (EEZ). Both the USA and Canada have substantial research programmes on North Pacific hake that cover stock assessment, biology, distribution, environmental change impacts, fisheries impacts, and approaches to conservation of non-target species. This information is used to provide scientific advice upon which Canadian and US authorities develop joint fishery management plans under an international agreement (8). Assessment Most assessments of hake stocks rely on commercial catch and fishing effort data, often supported by fishery-independent methods such as research vessel trawl and acoustic surveys (using echo sounders). The methods used to assess hake stocks vary by region and depend on data availability. It can be difficult to age hake accurately, which detracts from the robustness of stock estimates in several hake stocks. Where sufficient data on the age or length structure and biological characteristics of commercial catches are available, such as in the European, Argentine and Chilean stocks, it is possible to undertake an analytical assessment (known as a virtual population analysis) that models the age structure of the stock, spawning stock biomass (SSB) and other population variables, which can be used to evaluate the effects of exploitation on the stock. Production models may also be used to estimate the response of a stock to fishing and how much of the stock may be harvested without depleting its spawning potential. In their most basic form, they only require catch and fishing effort information, but information on age or length structures can be incorporated. This is the preferred approach for the South African hake
3 Responsible Sourcing Guide: Hake. Version 6 – March 2012 stocks. Until recently, a single combined stock assessment was conducted for the South African hakes (M. capensis and M.paradoxus). In response to conditions set on the MSC certification of the trawl fishery, each species is now assessed separately, using commercial catch data in an age-structured production model, supported by biological sampling of the catch at sea and onshore and acoustic surveys. The assessment of the Namibian stocks has been conducted along similar lines, using agestructured production models with commercial catch data. Maximum Sustainable Yield (MSY) and the precautionary approach Current ICES advice on fish stocks is described in terms of MSY and the precautionary approach. MSY relates to optimising yield, the precautionary approach to avoiding stock depletion. MSY means fishing at levels that catch the maximum proportion of a fish stock that can safely be removed on a continuous basis while, at the same time, maintaining its capacity to produce sustainable returns in the long term. The ICES MSY approach (9) is based on a strategy whereby catch rates are fixed, enabling fish stocks to reproduce so that exploitation can occur in sustainable economic, environmental and social conditions. The EU has a plan for transition to MSY in four steps from 2011-15. ICES advice takes this into account (10). However, in the shortterm, Seafish has classified fish stocks into six categories under the twin MSY/precautionary approach. Categories 1 to 3 will result in a recommendation for catches consistent with fishing levels which would result in MSY. For some stocks the MSY reference points are not defined. In these cases, catches are defined by the precautionary approach. Many hake stocks have a management plan agreed between the parties exploiting the stock, and scientific advice is given that is compatible with the plan, although not all plans are in line with the precautionary approach. Categories 4 and 5 will result in advice to rebuild stocks through reducing catches or other measures. Seafish categories Table 1: SEAFISH MSY / PRECAUTIONARY APPROACH CATEGORIES; see table 2 & Fig 1 1. Inside safe biological limits and fished at MSY. When a stock is of a sufficient size to reproduce and support a commercial fishery, and is also fished at MSY. 2. Inside safe biological limits but fished below MSY. Stock is of a sufficient size to reproduce and support a commercial fishery, but not fished at MSY. Fishing could be increased to achieve MSY. 3. Inside safe biological limits but fished above MSY. When a stock is of a sufficient size to reproduce and support a commercial fishery, but corrective action is required to reduce fishing to levels that are consistent with MSY (F MSY ). 4. Stocks at risk of being outside safe biological limits and below the biomass action point B MSY-trigger There is concern that the stock needs to be rebuilt and fishing mortality (proportion of the stock captured each year) is reduced to allow the stock to rebuild. In most cases, B MSY-trigger is set at the precautionary biomass reference level. 5. Stock outside safe biological limits. The stock is in a condition where there is concern that reproduction may be impaired. Action should be taken appropriate to each stock to further reduce fishing mortality and encourage stock rebuilding. 6. Reference points not defined. Where precautionary or MSY reference points are not defined or could not be assessed against. There may be indications that the stock is in good or poor condition which are described in Table 2. .
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