Fish and Shellfish Stocks: 2013

The Basis and Form of ICES Advice

For some years ICES based its advice on a precautionary approach defining reference points related to fishing mortality rate (F) and spawning stock biomass ( SSB). Where stocks were judged to be fished unsustainably (F above the reference points) or where recruitment was likely to impaired ( SSB below reference points) then restrictive advice could be expected. The rationale behind this approach is 'avoidance' of situations likely to lead to stock collapse. More recently there has been a shift in emphasis towards a 'target' based approach to management, where the emphasis is on fishing at a rate likely to lead to long term sustainability. This is exemplified in the concept of maximum sustainable yield ( MSY).

The goal of achieving MSY has an international legal basis, and was stipulated in the United Nations Convention on the Law of the Sea (1982) and Johannesburg Declaration of the World Summit on Sustainable Development (2002). The European Commission for Fisheries, DG MARE, has emphasised the importance of the target that all European fisheries are to be exploited for MSY By 2015.

The MSY approach is now prominent as the basis of the ICES advice, but the form of that advice is largely dependent on the availability of data and the quality of the assessment for each stock. Advice types can be broadly categorised as follows. It should also be noted that the ICES advice for fisheries should take explicit cognisance of the ecosystem impacts and consequences of fishing, but this aspect is not yet well developed.

Management plans
For several stocks, international management plans and agreements exist that stipulate suitable harvest control rules (and hence exploitation rates and appropriate removals). In many cases the exploitation rates align closely with MSY principles. If these stocks also have accepted age-structured assessments based on catch and survey data, then these are used to determine the advice. Examples include North Sea haddock, herring and cod.

Maximum sustainable yield ( MSY)
Where no agreed international management plan exists, the default ICES position for stocks with full accepted assessments is to base advice on a fishing mortality rate (known as F _MSY) that is expected to generate the MSY for the participating fleets: that is, the highest possible catch that can be maintained indefinitely. Examples include West of Scotland haddock.

This approach has superseded the precautionary approach ( PA), although PA biomass reference points are still in use for some stocks and PA advice is still listed.

MSY (or, more specifically, F _MSY) can be very difficult to estimate, and proxies to it are often used. It may be different in single-species and multi-species contexts, but it is generally the case that F _MSY is less than the historical fishing mortality rate experienced by a stock. Hence a requirement to fish at or around F _MSY usually leads to a reduction in fishing mortality, and a concomitant increase in sustainability.

'Data-poor' stocks
For all other stocks, the form of the ICES advice is principally determined by the requirements of the advice customer, which for ICES is often the European Commission ( EC). In an attempt to force member states to monitor and submit detailed data on all their fisheries, in 2011 the EC decided that only stocks with full, age-structured analytic assessments could be managed according to management plans or MSY considerations. All other stocks, including those with only (for example) research-vessel survey data, would be managed according to advice based on the following table. While the intention to improve data provision is laudable, questions need to be asked about whether a rigid approach to the type of assessments that are acceptable is appropriate. Robust assessments using different approaches also need to be considered. For now, the consequences of the consistent application of the table are that many stocks for which reasonable indicators of stock abundance exist are subject to quota cuts because these data do not fit a particular paradigm. Examples include Northern Shelf monkfish.

		No overfishing	Overfishing	Unknown exploitation status
Decreasing stock trend	or	Reduce catch at rate of stock decrease.	Reduce catch at rate greater than the rate of stock decrease.	Reduce catch at rate greater than the rate of stock decrease.
Stable stock trend		Do not allow catches to increase.	Reduce catch.	Reduce catch.
Increasing stock trend	or	Increase catch at rate of stock increase.	Do not allow catches to increase.	Do not allow catches to increase.
No trend information		Do not allow catches to increase.	Reduce catch.	Reduce catch.

The presentation of advice
However the advice is determined, the conclusions are presented in a consistent way for all stocks. The first element of the advice is a table (see above) summarising current stock status and, comparing this with the previous two years, for spawning stock biomass ( SSB) and fishing mortality (F). The status relative to particular reference points is summarised using a simple system of icons:

	Appropriate (below F target, or above SSB target)		Increasing trend
	At F or SSB targets		Stable
	Not appropriate (above F target, or below SSB target)		Decreasing trend
	Unknown

The example below is from the advice given in June 2011 for West of Scotland haddock (Division VIa)

F (Fishing Mortality)
	2008	2009	2010
MSY ( F MSY)				Appropriate
Precautionary approach (F pa, F lim)				Harvested sustainably

SSB (Spawning Stock Biomass)
	2009	2010	2011
MSY (B trigger)				At trigger
Precautionary approach (B pa, B lim)				Full reproductive capacity