Scottish Government

9. Managing the Stocks

Environmental uncertainty

9.1 Fisheries management is highly challenged by its task to undertake the sustainable exploitation of a natural resource within an unpredictable environment. The fundamental basis upon which fisheries operate is that they exploit animal protein that has been grown as a result of energy from sunlight being fixed by phytoplankton which are then eaten by other organisms. The route by which energy passes to the species that are fished commercially is complex and unpredictable.

9.2 This type of uncertainty means that it is not possible to manage ecosystems in a manner that will allow them to be optimised to produce protein that is in a commercially exploitable form. Evidence from around the world shows strong effects of fishing on the structure and function of many marine ecosystems. In some examples structural changes have resulted in shifts in the species composition that have not penalised fishermen, but in extreme cases there is evidence that the ultimate effect of chronic overexploitation is to reduce considerably the overall availability of commercial products. It is perhaps not surprising, if there is continuous harvesting of particular parts of the food web at levels too high for them to be replaced, that much of the energy within the ecosystem will eventually tend to reside in those parts that are not exploited and that are unlikely to be of commercial value.

9.3 Some evidence from Scottish marine system may indicate that certain changes that have been associated with overfishing in other temperate marine ecosystems may have occurred in Scottish waters. The increasing prevalence of shellfish (mainly Nephrops ) and the successful recovery of pelagic fisheries may owe something to the poor state of demersal stocks and fishing could be a cause of this poor state even though climatic factors will also have played a part. Unfortunately, our current understanding of the complex structure of marine food webs means that we cannot predict how they will respond to fishing. While we almost certainly have the power to shift the structure through fishing, we do not have either the knowledge or the agility within management to drive the structure of the ecosystem in a direction that will, with any certainty, make it maximally productive for fisheries.

Scientific uncertainty

9.4 Fisheries science is the source of information upon which many management decisions are based. However, fisheries science is challenged by uncertainties. These uncertainties emerge from several sources including the measurements of fish abundance (measurement uncertainty), the way in which data are assimilated and collated (process uncertainty) and the assumptions about how fish populations behave (model uncertainty). These uncertainties sit on top of the true, natural variability that there is within the distribution and abundance of fish. Fisheries management models are also limited by what is generally known as the 'ecological fallacy'. This occurs when scientists assume that all individuals in the fish population have the same genetic value in terms of their contribution to the future of the population. Almost all fisheries models include this assumption and this is an example of model uncertainty that probably affects the relative reliability of fisheries models depending upon the species.

9.5 A recurring criticism from the industry is that fisheries science is often wrong. As illustrated by the accumulation of uncertainties in data and the approaches to analysing those data, fisheries scientific advice is almost certainly always wrong to some extent. However, fisheries scientific advice is likely to be much less wrong about the status of stocks than other methods of assessment. The sampling methods used by fisheries science in Scotland are probably about as good as resources and current knowledge allow and are comparable with the best in the world.

9.6 The suggestion that the knowledge gained by fishermen should be used in the scientific process is especially difficult to achieve because anecdotal information adds more uncertainty about the validity of the information being used. However, there is considerable scope for using the fishing industry as a source of information about fish populations providing that protocols for data collection can be agreed between the industry and scientists. The current levels of scientific sampling using independent research vessels is going to be difficult to sustain because of increasing costs. New approaches to the collection of data involving cooperation between the industry and scientists will probably be the most effective solution and we encourage these developments.

9.7 Fisheries science has traditionally worked to gradually narrow down uncertainties in stock assessments to increase the reliability of scientific advice and to move from a generally retrospective picture of fish stocks to a more predictive framework. In spite of this, the prospect of greater precision in stock assessments is small within the foreseeable future. A more likely scenario is that we will become more appreciative of the boundaries of uncertainty in stock assessments. Evidence of greater precaution within the advice from ICES , mainly because of appreciation of these uncertainties, probably reflects this trend.

9.8 A rational system of management will adjust its level of precaution to the understanding of risk. Where there is imprecision, or uncertainty, there is additional risk so where imprecision is high the rational manager would proceed with caution which might mean, for example, setting a TAC at a very low level. The manager would only reduce the level of precaution, often manifest by gradually increasing the level of TAC set for a particular species, based upon evidence that reduces uncertainty. Unfortunately, the current management system within the CFP has not followed this type of rule and, as a result, there is strong evidence of chronic overfishing (see Chapter 3). The long history of fishing in European waters has meant that fishing began before science had the capacity to set rational limits and also before risk based management was understood. The result has been that the fisheries management system has had to be introduced retrospectively to a traditional approach to fishing in which the risks being taken, and the expectations of the fishers, were
already beyond those that would be considered to be acceptable based on current understanding.

9.9 The recent record suggests that rational risk based management is often ignored. In the case of monkfish a TAC was originally set with almost no information about the stock size. We can probably consider that it was simply good fortune that the early efforts to establish the monkfish fishery did not wipe out the stocks because the strategy of establishing a fishery with no information about stock size, and very little about the life history of the species, was inordinately risky. Fisheries for some other species such as some deep sea species like the orange roughy, have not been so fortunate. Closer to home, declines in skates, rays and sharks are probably attributable to those species having low tolerance to fishing. Indeed ICES considers the angel shark to have been driven to extinction in the North Sea by fishing.

9.10 Consequently, the joint problem of high (and sometimes undefined) levels of scientific uncertainty in data and the increasing realisation that the marine environment is intrinsically unpredicatable lead to the overall conclusion that there is little rational scope for fine tuning how we exploit the productive capacity of the oceans. Such 'fine tuning' is evident in the annual rounds of adjustments to TAC s. Although many within the fishing industry and the fisheries management systems may disagree, the evidence to date within Scottish waters as well as more globally, is that this is the case. A revolution in thinking is needed in order to take us down the road of building fisheries management around the principles of ecosystem sustainability. Unfortunately for the fishing industry, these approaches point increasingly towards downward pressure on the amount of fish that can be taken.

ICES advice

9.11 Within this context, we review briefly how ICES presents its advice to the EC about the status of stocks. The annual advice from ICES is meant to form the basis for setting TAC s. The documents produced each year for each part of our regional seas reflect enormous effort on the part of the scientists involved. As a result, the regional seas around Scotland are some of the most thoroughly researched anywhere. The annual 'books' of advice produced by ICES are prodigious in their detail. Although, Marine Scotland Science produces an excellent summary of the ICES advice as it relates to Scottish fisheries, we believe that the advice could be structured in a manner that makes the advice more accessible to non-specialists.

9.12 Overall, the ICES advice probably needs to be accepted on its face value because, although far from perfect, it is certainly the best information upon which to base management decisions. If we assume that the scientific advice is correct then the process that leads to a specified amount of fish caught is as follows:

9.13 In other words, the scientific advice is used to set the TAC and the TAC then leads to an actual catch that includes estimated discards as well as landings. This means that, if the management system is operating correctly, there should be a direct relationship between the scientific advice and the actual catches. In Figure 9.1, we illustrate the relationship between the first and second box (scientific advice and TAC ) and also between the second and third of these boxes ( TAC and actual catch) for three important Scottish fisheries. In all cases, the plotted relationships should follow a straight diagonal line from the bottom left to the top right of each panel in Figure 9.1. This is illustrated by the solid line in each panel. In a perfect management system the points on the diagrams would fall exactly on this diagonal solid line.

9.14 However, as can be seen, in only a few cases do the points lie close to the solid line. The dashed line is the realised relationship in each case. The top set of panels (a, b, and c) illustrates the extent to which ICES advice is implemented when setting TAC s (representing the relationship described by the arrow on the left of the flow diagram shown in paragraph 9.12. With the exception of cod, these appear to perform well on average. The problems with the implementation of the ICES advice about cod stem from the very low (effectively zero) catches advised by ICES and which the management system simply cannot accommodate if fisheries are to remain functional. Greater transparency in the production and use of ICES advice within the management process would avoid suspicion of external manipulation.

9.15 The bottom set of panels (d, e and f) illustrate the relationship between TAC s and realised catches. This reflects the thoroughness with which fisheries are regulated and the extent to which fishermen comply with regulations. In the case of haddock, and especially in the case of herring, there appear to be potentially important discrepancies between the TAC and the realised catch. In both cases the realised catch is well above the target line. The cause of this is debatable but it probably relates to discarding through high grading in the herring fishery. In the haddock fishery, deviation from the management targets are greater as the TAC s decline suggesting that the fishery has found ways of maintaining higher levels of catch than permitted under the management rules. Overall, this adds up to a failure in the effectiveness of enforcement.

9.16 In Figure 9.1 below each dot represents a different year. Fewer points are present in (a-c) because in several years the annual advice could not be presented as a predicted catch. The solid line illustrates the line that the points would lie on if the management system was followed perfectly from the preceding step in the sequence. The dashed line shows the actual relationship. Note that in some cases this lies so close to the line of perfection that it is difficult to see. The distance of the dashed line from the solid line gives a relative measure of the faithfulness with which the scientific advice is translated in to a TAC (a, b, c) and the TAC is translated in to a catch (d, e, f).

Figure 9.1 The annual TAC for North Sea cod, haddock and herring plotted against the annual ICES Advice (a, b, c) and the annual catch, including discard estimates, plotted against the annual TAC (d, e, f) for the period 1987 to the present.

Source: ICES various

9.17 Many may argue that the reasons for the discrepancies evident in Figure 9.1 between TAC and realised catch in the case of haddock and herring have been dealt with through the elimination of blackfish from the markets, but what this illustrates in a very general way is that, contrary to some assumptions, the EU (together with member states) appears to implement the ICES advice with a high degree of fidelity, as demonstrated in these three key stocks, but the way that TAC s are carried through in to catches is less well regulated and provides evidence of overfishing.

9.18 This illustrates another important type of uncertainty in the system of fisheries management, namely the uncertainty associated with the implementation of management decisions. In other words, not only are there uncertainties in the scientific basis for decisions, but the decisions themselves are implemented in a very imperfect way. Managers need to take this in to account when setting TAC s, or effort controls. In any risk based system of management this will inevitably also bring downwards pressure upon TAC s or effort.

The ecosystem approach

9.19 Given the apparently limited capability to precisely manage fisheries what can be done to improve fisheries management? An early response to this question that emerged in the 1990s was the ecosystem approach to fisheries management. Although there were many interpretations of what the ecosystem approach involved, it has actually boiled down to a minimalist tilt towards greater environmental awareness within fisheries management. Traditional fisheries management approaches have remained fundamentally intact but now have an additional layer that allows adjustment of the outcomes, such as TAC s, for other ecosystem factors. In some cases there are also what are called multi-species TAC s which mean that TAC s for different species are not set in isolation from one another. Overall, the ecosystem approach has proved to be difficult to implement - mainly because it was poorly defined - and has, arguably, brought another decade of minimal adjustment to the current approach to fisheries management.

Towards productive fisheries

9.20 Notwithstanding these problems, we can probably achieve better productivity and better management even if there are no significant improvements in our knowledge of ecosystems and fish populations. This probably means moving away, perhaps quite abruptly, from the traditional forms of target setting. It also may mean moving to considerably lower levels of fishing than currently practiced - although with time this may not mean reduced absolute amounts of fish available to commercial fisheries.

9.21 The CFP only requires fisheries to be exploited sustainably. In contrast, the Marine Strategy Framework Directive (see Chapter 8), together with the UN Convention on Biological Diversity, establish the principle of Maximum Sustainable Yield ( MSY ) as a target for the exploitation of fish populations. MSY is the population size at which there is a maximum yield above what is required to replace the stock and it derives from the underlying biology of the species concerned. Much of the ICES advice is pitched towards achieving a fishing mortality that achieves MSY .

9.22 Superficially, MSY is a reasonable target for management but it has some serious difficulties that derive from the difference between the theory of how fish populations can be managed and how management can be implemented in the face of high uncertainty. Nevertheless, as a first step, we suggest that the most pragmatic approach is to aim to ensure that stocks are exploited at a level that is not greater than the theoretical MSY⁵ . Having achieved this and built information about the performance of the fish stock the level of fishing mortality associated with MSY should be critically reviewed with a view to possibly introducing further reductions in fishing pressure. In the case of stocks, such as monkfish, in which there is unlikely to be sufficient information to establish the MSY , it would be necessary to maintain a high level of conservatism about the exploitation level. It remains a general concern that MSY still appears within European targets for managing fisheries. MSY , or its equivalent, is not precautionary from a fish conservation perspective.

9.23 The concept of Maximum Ecological Yield ( MEcoY ) is likely to gain ground in future. This embraces many of the requirements of sustainability within fisheries and also those associated with multiple competing objectives within marine management. It also starts to address the difficult issues concerning the tendency for sequential overexploitation of fish stocks. Some fisheries are being managed using an F_0.1 strategy ⁶ which is more conservative than an MSY approach. However, there is a view that this is still not sufficiently conservative.

9.24 A management strategy that is focused upon harvesting at MSY will normally set F at a level that will lead to about one third of the stock being taken by the fishery each year ⁷ . Fishing mortality in many of the major Scottish fisheries exceeds this level by a considerable amount (see Table 9.1). None of the fisheries show the characteristics of a MEcoY approach to fisheries management, where the targets being set and achieved would probably be considerably lower than MSY and would reflect the risk because of uncertainty. The evidence for overexploitation is strong because the recent level of fishing exceeds the target level in all cases and the long term level of exploitation is well above target levels. Even the target levels appear to lack appropriate inbuilt precaution (also see Chapter 3).

9.25 The management system for these species has a tendency to overshoot the Target F mainly because of economic, social and political pressures to sustain high yields. This can lead to catches that are higher than can be sustained in the long term. While the uncertainties in the system will allow managers to get away with this for a while, permitting realised values of F that are consistently above these target levels is irresponsible. This is because every time the target F is exceeded a risk is being taken. Unfortunately, the risk taken by setting a high TAC in one year is not independent of the level of risk being taken in other years. If a risky management strategy is followed on a consistent and long term basis then the probability of inducing stock collapse increases through time. However, a more insidious possibility is that the system will shift gradually toward pushing energy in to commercially unexploited products.

Move to a low- F fishery

9.26 We appreciate that there are some very difficult messages here for the fishing industry. The industry has probably enjoyed access to resources over the past few decades that are considerably beyond those that can be considered sustainable. The consequences of this may not be immediate but may be felt by future generations as the Scottish marine ecosystem adapts to long term overfishing by diverting the energy of the system in to ecosystem products that are of no commercial value. We do not know for certain that this will happen but it is a reasonable possibility unless a more conservative approach to management is adopted.

Table 9.1 The mortality caused by fishing in some of the major commercial fish stocks in Scottish waters.

Source: Marine Scotland

The value of F is given but this is followed in parentheses by the percentage of the stock that is taken each year. The long term mean is the average value of F since records began; the recent F is the average during the past 5 years and the Target F is the management objective. Data supplied by Marine Scotland.

9.27 The Panel is also acutely aware of the trends underlying the societal expectations of fisheries and how they relate to the sustainability of the marine environment. These are largely reflected in the provisions of the Marine Strategy Framework Directive (see Chapter 8) but also appear in the rapid uptake of eco-labelling and stewardship accreditation schemes. The current development of MEcoY , mainly within academic settings, as a principle for management is, in the view of the Panel, likely to grow in acceptance. This is likely to lead to further downwards pressure on fishing mortality to levels that are probably a small fraction of the current levels for some species. For fisheries to be successful within this very challenging set of circumstance there is probably a need for the development of a process that evaluates the costs and benefits (to the fisheries, fish stocks and environment) of different management strategies. Some tools are available for this within fisheries management (known as Management Strategy Evaluation, or MSE ) and these should be implemented broadly across Scottish fisheries. ⁸

9.28 Notwithstanding the outcome of such an evaluation, the general recommendation that the fishing mortality rate should be reduced fulfils several objectives:

i. fisheries in which F is low are likely to be at least as profitable and, because stocks are likely to be high and may yield at least as much marketable fish as is available presently at much higher levels of F ;

ii. bycatch becomes a considerably reduced concern because the levels of fishing relative to the stocks may be low enough that bycatch is a smaller proportion of population size. Consequently, 'land all you catch' scenarios become more plausible;

iii. conflicts with the objectives to meet the targets set for the quality of the ecosystem will be reduced or eliminated because fisheries will be operating within the targets set under the definitions of 'Good Environmental Status' in the Marine Strategy Framework Directive;

iv. the level of information needed to manage the fishery is much reduced because no effort is being made to finely tune TAC s to targets based upon new information. There may be no need, for example, to establish the population status of stocks on an annual basis;

v. it would be possible to set longer term TAC s and avoid annual bartering rounds for new fishing opportunities because the exploitation levels will be low compared with the size of stocks and the need for annual review of exploitation levels will be reduced; and

vi. it will help to resolve conflicts between management for MSY of individual stocks and management of the MSY for the fishery because these approaches tend to converge at low exploitation levels.

9.29 The difficulty, of course, with aiming for a low F fisheries policy is the economic and social challenge of moving to this new approach. However, given the benefits, the pain associated with this is worthwhile and is probably unavoidable. Consequently, the Panel recommends:

• a stepwise, planned approach to adjusting the fishing capacity downwards to achieve considerably lower levels of fishing mortality than is the current norm;
• as a first step, this should involve a rapid progression towards the target F as estimated by ICES , probably within the next few years; and
• as a second step, there should be a review of whether lowering F further is likely to result in increasing fish biomass, potentially producing increasing fishing opportunities, and allow fisheries to play their part in developing a robust approach to the management of marine biodiversity and the marine ecosystem as a whole.