Stock Assessment

Sustainability Review

Two of the major processes that the Ministry run each year are the fisheries stock assessment processes, and the subsequent provision of sustainability advice to the Minister. These processes were reviewed in November 2007, and a number of opportunities for improvement were identified. Several of these changes were incorporated into the assessment working group and plenary processes that took place from January to May 2008. Further recommendations will be implemented at the appropriate points during the current and future cycles of these processes.

The State of New Zealand’s Fisheries

There are many ways to manage fisheries. These include simply limiting the size of vessels, or limiting the numbers of days they can fish each year, or limiting the amount that can be caught in a day or in a year. New Zealand has chosen to set Total Allowable Catches (TACs) to limit annual catches as the primary management mechanism. This is generally thought to be the most effective management method world wide.

The rationale for setting and varying TACs is specified in our Fisheries Act (1996) which states that fisheries must be managed so that stocks are maintained at or above the biomass associated with the maximum sustainable yield (MSY). TACs need to be modified to track natural fluctuations in stock size and/or to correct the effects of historical overfishing. In reality, there are limitations to the frequency with which TACs can be varied. One of these is the limited amount of information on stock status for many of our stocks. New Zealand is a small country and has limited human and financial resources to be able to collect extensive information on all 629 fish stocks currently in the QMS. As a result, our research budget is prioritised so that we focus on the stocks with the highest landings or value, or those most at risk of being unsustainable.

There is currently sufficient information to characterise stock status (ie the size or state of a fish stock relative to MSY benchmarks) for 101 of the 629 stocks in the QMS. This accounts for 69 percent of the total landings by weight and value and represents the main commercial species4.

Of the 101 stocks or sub-stocks with known status, 72 (71 percent) are near or above target levels. In most cases, these targets are at or above the biomass associated with MSY, or related levels. The 29 stocks that are known to be below their respective targets include three highly migratory species (over which New Zealand has limited influence), one of the two stocks of hoki, several orange roughy stocks, gemfish, one paua stock, west coast North Island snapper, all bluenose stocks, several other smaller inshore stocks and longfin eels (for further details go to: www.fish.govt.nz/en-nz/ SOF/StockStatus.htm). However, it should be noted that just because a stock is below its MSY-related target, it does not mean that the stock is being fished unsustainably. It simply means that the stock must be fished at a lower rate to enable it to rebuild.

A number of different actions are being taken to rebuild these stocks. For example, the hoki Total Allowable Commercial Catch (TACC) has been substantially reduced over the last few years and, as a result, the depleted western stock of hoki is showing definite signs of rebuilding. Fisheries for two of the orange roughy stocks have essentially been closed for several years, with a third fishery being closed in 2007. A third consecutive year of continued TACC reductions has been proposed for the main Chatham Rise orange roughy stock. Bluenose stocks were identified as being in need of rebuilding in May 2008, and substantial quota reductions have subsequently been proposed and put out for consultation with stakeholders. Rebuilding programmes or TAC/TACC reductions have been put in place for all other depleted stocks. These interventions are evidence of New Zealand’s willingness to take action as needed to effectively manage our fisheries.

Research leading to new assessments of stock status in early 2008 revealed that one southern blue whiting stock and two rock lobster stocks have now rebuilt beyond target levels and TACCs were increased accordingly.

It is difficult to directly compare the summary statistics on stock status for the current year with those from last year. The 2006/07 Annual Report indicated that of the 85 stocks for which we had sufficient information to characterize stock status, 72 (85%) were near or above target levels. This year, the total number of stocks with sufficient information has increased substantially, while the percentage near or above target levels has declined. The main reason for the increase in the number of stocks of known status is that status evaluations for several species that have recently been introduced into the QMS have now been completed. The main reasons for the decrease in the percentage near or above target levels are that recent stock assessments for several stocks have changed the stock status from a favourable to an unfavourable categorisation, and that the assessment information for some stocks is too out-of-date for their current status to be characterised. Of the 85 stocks reported on in 2006/07, the status of nine stocks (two orange roughy, four bluenose, two highly migratory species and one paua) changed from a favourable to an unfavourable categorisation.

The large increase in the number of stocks of known status and the transfer of stocks between “known” and “unknown” status categories means that the basis for comparison of simple statistics between years is not consistent. For this reason, the Ministry is currently investigating alternative, more consistent measures that may be reported on in future years.

Stock Assessment and the Effects of Fishing Research

Research is essential for determining the size and health of fish stocks and the extent to which they can be used sustainably. Such data is crucial for sound fisheries management, particularly for setting catch limits.

In 2007/08, the Ministry’s fisheries research budget was $17.6 million, excluding biodiversity research. This research supported data collection, monitoring and stock assessment programmes for several middle-depth, deepwater, inshore, non-commercial and Antarctic stocks. These programmes, along with previous research, led to new stock assessments being completed for orange roughy, hoki, gemfish, hake, ling, rock lobster, toothfish, bluenose, tarakihi, stargazer, paua and cockle stocks.

Two Plenary documents, summarising catch histories, fisheries characteristics, biology and stock status, were produced: one for rock lobster and toothfish in November 2007, and another for 80 different species in May 2008. As a result, changes in TACs were proposed for rock lobster, southern blue whiting, orange roughy and bluenose – the former two were increases, the latter two decreases.

Management decisions in 2007/08

Changes to the catch limits in the past year included adjustments for certain orange roughy and oreo stocks, hoki, North Island eels, northern tarakihi and school shark, southern flatfish and red cod, and Marlborough dredge oyster fisheries. These limits came into force on 1 October 2007.

In March 2008 the Minister increased the catch limits for the rock lobster (crayfish) and southern blue whiting fisheries in the waters around southern New Zealand.

The increase in rock lobster catches are worth an estimated $11.5 million a year to fishers, while the increase in the southern blue whiting catch are worth an estimated $4.7 million a year.

The Minister also adjusted deemed value rates (charges that are imposed on commercial fishers to discourage catching in excess of their catch entitlement) for 28 fish stocks.

Both the increased catch limits and the amended deemed values took effect on 1 April 2008.

Regulation changes in 2007/08

The Minister announced a number of minor regulatory changes that came into effect on 1 October 2007. These changes were widely consulted on and will assist us in managing our fisheries sustainably.

Kahawai decisions

In 2008 the decision was made to delay the review of sustainable catch limits, and other management measures for the kahawai fishery until 2009. The Crown has already agreed that catch limits and allowances for all kahawai stocks would be reviewed at the next opportunity in light of the decisions of the High Court and Court of Appeal. This will still go ahead, but it was decided that there was not adequate time to carry out these reviews, consult with stakeholders, and make decisions before the start of the new fishing year on 1 October 2008.

Research into the aquatic environment

During the 2007/08 year, the Aquatic Environment Working Group has considered a wide range of research projects on the environmental effects of fishing, including bycatch of protected species, fish bycatch, impacts on benthic environments, habitat mapping and ecosystem indicators. The Ministry is working toward a plenary-type document – or Aquatic Environment synopsis – that provides a summary of the best available information of the effects of fishing and aquaculture on the aquatic environment. A draft of this report is due out later this year for consultation.

The Ministry also administers a Biodiversity Research Programme, as part of the New Zealand Biodiversity Strategy 2000. The Biodiversity Medium-Term Research Plan was significantly revised in 2007/08, and a five-year project plan was developed for work on seven strategic directions in the areas of: ecosystem-scale biodiversity; habitat characterisation; functional ecology; genetic diversity; climate change; measurement of diversity; and threats to biodiversity.