The imperfections in the fisheries management system, including uncertainties in management objectives, fishery and biological data, environmental oscillations, stock assessment methods, economic parameters, management advice, management measures and fishermen's behaviour have been recognized long ago (Larkin, 1972; Gulland, 1983). Gulland stressed the fact that “imperfections that exist in all parts of the system…should not be an excuse for postponing action until matters are improved” and that management action should be modified “recognizing these imperfections and learning to live with them rather than attempting to eliminate them”. It is easy to recognize the precautionary approach in this 12 year old prescription to (a) recognize and accept uncertainty; (b) not delay action until more is known, and (c) learn to live with incomplete information. The solutions offered included, raising awareness on uncertainties and developing opportunism, flexibility and adaptation in management and development. These and other precautionary measures for fisheries management, have long been advocated as a means to avoid crises and higher costs to society (Walters and Hilborn, 1978). They have not often been applied in practice because more attention has been paid to short-term costs while long-term benefits have not been properly valued. Crisis management is unlikely to offer sustainable solutions to the problems encountered by fisheries.
Risk is unavoidable when deciding on harvest levels aiming at a range of conservation, social and economic (and political) objectives (Shotton, 1994). In such situations, decisions should be consistent with the theory of rational choice but the uncertainties on the data and models, as well as the differences and changes in the various users' preferences, make it impossible to define any optimum to be used as a single, resultant, management target. As a consequence, it is necessary to reflect the targets and constraints (both biological and economic) as “Reference Points”, as landmarks which flag desirable or critical states of the known components of the system and which can be used to determine and influence the “position” of the fishery in relation to the multi-dimensional environment they materialize.
What is new in the modern requirement for precaution is not so much the sort of management measures that are suggested but the fact that they would be automatically enforced, with no exceptions, and that they should be implemented as soon as a serious and potentially irreversible effect is detected (Hey, 1992). In recent years, the major impulses towards precaution have been associated with crises. The stand taken by FAO (similar to that taken by IUCN (Cooke, (1994); see Section 3.2), is that a progressive but systematic and decisive shift towards more risk-averse exploitation and management regimes is preferable, for all users, to the present combination of a general “laisser-faire” policy with a few mediatic bans and with significant negative socio-economic impacts. The problem is, therefore, one of promoting effective caution in fisheries to the point where the risk of an irreversible impact on the environment and resources (and ultimately on the fishing communities) will be reduced below the level which would call for drastic measures with potentially irreversible damage to the fishery sector and the coastal communities. This could be achieved by exerting caution systematically, at all levels of the management process, to reduce substantially the probability of errors and the level of potential damage.
It must be realized, however, that extreme interpretations of the concept of precaution, which would lead to unnecessarily stringent and costly measures, could rapidly become counter-productive by deterring fishery authorities from using the concept as widely as possible.
It is often supposed that preventive (or proactive) approaches to management are more precautionary than reactive ones because they anticipate unwanted events through knowledge of the system. According to Boelaert-Suominen and Cullinan (1994), the principle of preventive action is based on “the recognition (or assumption) that it is cheaper, safer, and more desirable (in the long term) to prevent environmental harm than to rectify it later, if indeed this is feasible at all” (comments between brackets added by the writer). A strong and unwarranted assumption behind the principle of preventive action, however, is that there is enough knowledge to allow such events to be reliably anticipated and avoided. Unfortunately, as shown in Section 4, fishery systems are not fully predictable and errors are always likely. As a consequence, a precautionary management strategy would need both sufficient foresight to avoid predictable problems, and enough reactive (corrective) capacity, flexibility and adaptability to ensure a safe “trial-and-error” process, as knowledge about how the system works is collected (stepwise decision-making). In this respect, the importance of feed-back, adaptive probing strategies, and learning, for the improvement of management regimes, have been stressed inter alia by Walters and Hilborn (1976), Walters (1981, 1986), Parma and Deriso (1990), Hilborn (1994) as well as Hilborn and Smith (1995). In theory, probing should provide the optimal solution but Shane and Peterman (in press) provide a “Bayes equivalent” approach which should give a close approximation of the optimal strategy.
Because of uncertainty, it is not prudent for management to rely on deterministic pseudo-quantitative reference points of dubious precision for a target-based management (e.g., a management regime based on deterministic targets such as TACs and quotas). Precautionary management strategies would recognize the uncertainties in the data and promote adaptability and flexibility through appropriate institutions and decision-making processes, according priority attention to the biological limits of the resource. These strategies would rely not only on expert advice but also on effective people's participation. In case of doubt, decisions rules should “err on the safe side” having due regard to the risk for the resource and to the social and economic consequences in both the long and short term. A precautionary approach to fisheries management implies agreement on action to be taken to avoid a crisis as well as action required if such a crisis occurs unexpectedly. Agreement on such action, at national or international level, implies the existence of agreed standards, rules, reference points, critical thresholds and other criteria as well as consensus on acceptable levels of impact. These concepts will be examined in detail below.
7.1 Acceptable Impacts
There is no doubt that fisheries have an impact on the ecosystem, reducing species abundance and reproductive capacity, possibly affecting habitats and genetic diversity. Some species might be endangered, especially when fisheries, natural variability and environmental degradation by other industries combine their effects. An impact on the resource base cannot be totally avoided if fisheries are to produce a significant contribution to human food and development. However, the biological effects of fishery activities are usually reversible and experience has shown that trends in biomass and species composition can be largely reversed when fishing effort is curtailed or fisheries are closed, even though rehabilitation may take some time and the characteristics of the “rehabilitated” system may not be accurately predicted21. Degraded habitats may require particularly long recovery times and higher rehabilitation costs.
If development and benefits are to be obtained from fish resources, some level of impact has to be accepted and a zero-impact strategy would be impossible to implement in practice. It would therefore be necessary to: (a) identify and forecast fishery effects (and risks) accurately enough; (b) agree on acceptable levels of impact (and risk), and (c) develop management structures capable of maintaining fisheries within these levels. The wide use of such subjective terms as “detrimental”, “harmful” and “unacceptable” to qualify unwanted impacts in expressions of the need for precaution is not very conducive to consensus and more efforts are required to specifically identify (preferably, by species and by region) what constitutes a risk and what risk is acceptable or not.
An acceptable impact could be defined as a negative, or potentially negative, alteration of the exploited natural system, resulting from human activities (i.e., fisheries and other impacting industries), the level and nature of which is considered as representing a low risk for the resource, system productivity, or biodiversity, on the basis of the available knowledge and level of uncertainty. Such a definition implies that: (a) the risk has been assessed using the best available evidence by all parties concerned, which agreed to it, in the light of the objectives stated for the resource, and (b) the impact will never be fully accepted (in the sense of definitely approved) but it will be kept continually under review and a decision about its acceptability eventually modified as knowledge progresses. The concept of acceptable impact may be related to that of assimilative capacity. This capacity, which has generated considerable debate amongst those concerned with environmental protection (Hey, 1992), has been defined as “a property of the environment which measures its ability to accommodate a particular activity or rate of activity without unacceptable impacts” (GESAMP, 1990). It assumes that nature might be able to absorb a certain quantity of contaminants (e.g., effluents from urban concentrations, radioactive waste, heavy metals and other causes of dramatic and potentially non-reversible impacts) without significant effect. The debate and opposition to the concept stemmed inter alia from: (a) opposition to the idea that oceans could legally be used for dumping, and (b) difficulty of determining objectively and agreeing on the evidence of innocuity or harmfulness of small concentrations of contaminants.
21The introduction of exotic species and genetically modified organisms may be the most notable and serious exception to this observation as it is generally impossible to remove species (and certainly genes) from the ecosystem once successfully introduced
In fisheries, however, the problem is different. Fishery resources do possess an assimilative capacity in terms of the fishing mortality they can withstand while still conserving most of their resilience or capacity to return to their original state once the fishery-induced stress is removed22 In a way, the concept of Maximum Sustainable Yield, enshrined in the 1982 Convention, could be considered a reference point corresponding to the “maximum assimilative capacity” of a stock in terms of fishing stress, i.e., a level of stress beyond which fisheries should not be allowed to go and, perhaps, not even to approach (see Section 7.2 on MSY as a reference point). The situation becomes more complex when considering the assimilative capacity of a multi-species resource or an ecosystem for which no means of measurement is yet available.
The degree of acceptability of impacts (or risks) will be determined, inter alia, in terms of risk-benefit trade-offs with proper weighting given to long-term societal needs and value of natural assets. This requires research capacity to separate the effects of “natural” year-to-year fluctuations and the impacts of fishing from anthropogenic degradation, including global climate change. It requires the development of an effective enforcement capacity to ensure that such levels will be respected. Finally, it may also require the establishment of “safety net arrangements” (e.g., in terms of insurance, compensation, etc.) to protect the users from hazardous occurrences.
There is no scientific criteria to determine objectively what is acceptable to society23. It is likely, however, that what may be acceptable to some countries or user-groups may not be acceptable to others (an argument developed by Dommen, 1993), and the relevance and importance of traditions and culture in this respect should not be underestimated. One of the important prerequisites for the effects of fishing to be acceptable to society could be that they should be reversible24 if the fishing pressure is reduced or suppressed. Referring specifically to ecosystems, Holling (1994) stressed that “temporary erosion of any one (of the sources of renewal capacity) might be bearable as long as recovery occurs within the critical time unit of one human generation. But continued erosion of even one (of these sources) eventually reaches the point where it cannot be reversed by normal internal recovery”.
Decisions on what impact could or could not be allowed are comparatively easy when risks are known and extremely high. Proposals to prohibit, even without any scientific background, the use of explosives to fish (say, in the high seas) would probably not meet with much international opposition because harmful fisheries techniques (e.g., dynamite and poison) are normally banned by national fisheries legislation. However, deciding whether a 5% by-catch of sharks in a long-line tuna fishery (or whether a 10% probability to drive a stock below its theoretical biological safe limits) is acceptable would require more careful consideration and debate. Science should provide the methods needed to forecast and measure the impacts, as well as objective criteria on the basis of which agreements can be reached. The difficulty in this regard will not be less than in other scientific mandates (e.g., that of determining MSY) and we should expect considerable scientific argument on the type of impact one might expect and on the level of certainty with which it can be determined.
22Except in the case of serious damage to the habitat, introduced species and GMOs
23Even though alternatives and their consequences (including for society) can be scientifically analysed and transitory agreements might be reached on their basis
24It has already been mentioned that this requirement was particularly critical in the case of introductions of species and GMOs
The degree of acceptability of any impact will only be established after intense negotiations between the parties concerned. These are unlikely to proceed easily or rationally if undertaken in a context of crisis. It is, therefore, advisable to integrate negotiations on impact into the management process before stocks are damaged and before potential socio-economic problems reach an overwhelming level. Cooke (1994) proposes, for instance, that when information to set a full-fledged management system is lacking, precautionary exploitation rates could be limited to 1% of the original biomass estimate. He argues, rightly, that this rate might still be too high for some very long-lived species. One could argue, however, that such a rate would be extremely low and hardly justifiable for short-lived tropical species where sustainable annual catches can be equal or higher than standing stock biomass and might sustainably be about 30–50% of the virgin stock biomass. Returning to the old approximative rule that the fishing mortality at MSY is close to natural mortality (Gulland, 1971) and while recognizing its shortcomings, one could nonetheless suggest a less arbitrary and more flexible precautionary rate of exploitation. One could, for instance, decide that precautionary exploitation rates should never approach natural mortality rates (if only because catching MSY is not desirable) and be limited to, say, 25% of these levels. For example, it could be decided that the precautionary level of fishing mortality in absence of data, Fprec, should never be higher than 25% of the natural mortality rate, leading to catches below 1% of the biomass per year for very long-lived animals, but well above 25% for others, with equivalent degrees of precaution.
7.2 Management Principles and Decision Rules
Once agreement has been reached on what risk and what levels of impact are acceptable, one of the major tasks for research and management is to develop agreement on standards, rules, reference points and critical thresholds by reference to which decisions will be made to meet the selected management objectives and the requirements of the 1982 Convention, UNCED Agenda 21 and the FAO Code of Conduct. Over-restrictive rules (e.g., rules implying socio-economic consequences without proportion to the risks involved) or recommended without a clear understanding of their practical implications, are not likely to lead to the level of consensus required for the wide application of a precautionary approach required in UNCED Principle 15.
Because of the universality of conservation principles, precautionary management rules need to be established for all resources whether in EEZs or in the high seas. Because of the transboundary nature of many high seas resources, straddling stocks and highly migratory species, precaution should be applied across the entire area of distribution of the stock. This implies that coherent precautionary management regimes should be put in place, taking into account the geographical location of critical life phases (e.g., nursery, feeding or spawning areas) and ensuring that the measures taken inside the EEZs, and outside them, are coherent and are, overall, conducive to stock sustainability at safe levels of abundance. The following list gives some examples of principles or decision rules that have been proposed in the literature with a view to illustrating both the need for them and the difficulty of defining them in realistic terms:
fisheries should not result in the decrease of any population of marine species below a level close to that which ensures the greatest net annual increment of biomass;
fisheries should not catch amounts of either target or non-target species that will result in significant changes in the relationship among any of the key components of the marine ecosystem of which they are part;
the mortality inflicted on any target or non-target species is unacceptable if it exceeds the level that would, when combined with other sources of mortality, result in a total level that is not sustainable by the population in the long term;
fish management authorities should set target species catch levels in accordance with the requirement that fishing does not exceed ecologically sustainable levels for both target and non-target species;
fisheries management should take into account the combined stresses imposed by fishing, habitat loss and destruction, point and non-point sources of pollution, climate change, ozone level changes and other environmental and human impacts, and
fishery management should preserve the evolutionary potential of aquatic species.
The first principle implies that populations should not fall below the level of abundance corresponding to MSY, where their annual rate of biological production (turnover) is the highest. This is in line with the 1982 Convention requirements. It has been repeatedly shown, however, that it is often inadvisable to try to extract the MSY from a resource. Moreover, for multi-species fisheries, this principle would require that all species be exploited below their MSY abundance and, therefore, that the overall level of exploitation be fixed at the lowest level required by the species with the lowest resilience, reducing drastically the utility of the resource25.
The second principle, which rightly aims at preserving the qualitative parameters and fundamental integrity of the ecosystem mechanism, implies that fishing will not “significantly” disturb the food chain (an unreasonable assumption), without guidance on how to judge whether an observed or potential disturbance is significant. Moreover, fishing all species at MSY, if at all possible, would lead, in practice, to applying different fishing mortalities to different species and this would lead to a change in relative abundance of species, affecting the food chain. As a consequence, the second principle may be difficult to implement in many fisheries and may not even be always consistent with the first.
The third and fourth principles require that all sources of mortality are taken into account when assessing fisheries impact. These would include natural mortality as well as direct and indirect fishing mortalities (through by-catch, drop-out, damage, ghost-fishing, etc.). In practice, this principle implies also that mortalities imposed by non-fishery users (e.g., through environmental degradation) should also be taken into account. A very demanding task indeed, in most cases beyond the present capacity of research systems, even in the developed world. Assuming that the task implied by the third principle is feasible, a problem remains with the vagueness of the term “sustainable” in the formulations. In theory, fisheries are “sustainable” at various levels of stock abundance and rates of harvesting, but these are not equivalent in terms of risk of recruitment collapse. Surplus production models, on which the concept of MSY is based, assume that natural renewable resources are “sustainable” (i.e., able to regenerate themselves year after year) at various levels of abundance depending on the level of harvest (Figure 1). A stock can in theory reproduce itself, and be considered sustainable, at high (virgin state), medium (MSY level) and even low levels of abundance, except for some species such as marine mammals and sharks. However, as stocks are fished down, their variability and the risk of collapse increases and it should be clear that all levels of theoretical “sustainability” are not equivalent in terms of risk for the resource. To be of practical use in fishery management, the concept of sustainability needs to be combined with the notion of risk for the resource and consequently to the fishing communities.
25In a typical Mediterranean multi-species trawl fishery, where long-lived bottom species (e.g., seabream and red mullet) are targeted together with short-lived pelagics (e.g., sardine), this would imply fishing sardine well below the possible level of harvest in order to comply with the guidelines for seabream and mullet. The problem has been recognized in the report of the FAO Expert Consultation on Large-Scale Pelagic Driftnet Fishing (Rome, 1990)
The fifth principle, which in itself is perfectly laudable, has been reproduced only to illustrate the difficulty in practical implementation of some prescriptions. It is clear that the scientific data necessary to understand and forecast the impacts of all the sources of stress listed in the principle, some of which are still in the very early stage of study, are not available. As a consequence, they cannot be “taken into account”. The point, however, that all stresses need to be addressed, including those imposed by non-fishing or related to natural fluctuations, is well taken and has been underlined in the FAO Code of Conduct.
The sixth principle would imply that fishing should only be allowed in a way which would not affect the ability of an exploited population to respond and adapt to natural and anthropocentric perturbations (including by fishing) on the population or its environment. This is a commendable proposal considering our uncertainty, on the value of specific genes and genetic variations, on the number of sub-populations necessary for ensuring stock viability in all conditions and on how fishing affects genetic resources. To comply with the proposal despite all uncertainties, however, management would actually have to aim at maintaining all the genes and genotypes present in the virgin stock. Since genetic variation is directly related to population size, such a management scenario would not allow any reduction of the population size at all and, therefore, any fishing at all. A proposal unlikely to generate consensus.
Figure 1: Relationship between fishing mortality (or effort) and sustainable yield.
7.3 Precaution and Management Reference Points
Reference points have always been used in management, explicitly or implicitly, and are not a particular characteristic of the precautionary approach to fisheries. Precaution will relate to the choice of reference points (and their resource-related properties) and to the way in which they are used.
A management reference point is “an estimated value derived from an agreed scientific procedure and an agreed model to which corresponds a state of the resource and of the fishery and which can be used as a guide for fisheries management”26. This definition stresses the fact that reference points are conventional constructions based on the knowledge and often on a model available at the time of their adoption. As a consequence, they are meaningful only with a reference to the underlying theory and model, method and data used for their estimation as well as species to which it applies. The consequence is that reference points should be re-assessed periodically as new data is collected and as new understandings or methods become available, there would be great danger of “chiselling them in marble” as was done for MSY in the 1982 Convention. In the paper prepared by FAO for the UN Conference on Straddling Fish Stocks and Highly Migratory Fish Stocks, (FAO, 1993a) two types of management reference points are described: Target Reference Points (TRPs) and Limit Reference Points (LRPs). The review has been further developed in Caddy and Mahon (1995) and additional references can be found in Rosenberg and Restrepo (1995). A tentative definition of these points is given below.
The MSY Reference Point
The 1982 Convention states that stocks should not be driven below the level of abundance that could produce the Maximum Sustainable Yield (MSY). For decades, MSY has been used, explicitly or implicitly, as a reference point by research, development and management and considered as a bottom-line threshold for stock “sustainability”27. Research has amply argued, since the early sixties, that even at MSY, stock instability and risk of recruitment failure are sometimes already high (Christy and Scott, 1965; Larkin, 1977; Gulland, 1969, 1977, 1978; Sissenwine, 1978). This, added to the fact that MSY and the fishing rate corresponding to it are usually difficult to determine accurately, should lead to consider MSY as a non-precautionary target, particularly for stocks with low resilience or high natural variability. At the 1992 FAO Technical Consultation on High Seas Fishing, attention was drawn to the non-precautionary nature of the traditional MSY reference point and to the need for more and different reference points as a basis for more precautionary management strategies (Garcia, 1992). New reference points, not foreseen in the 1982 Convention are, therefore, required if management aims at a low risk of collapse.
Target Reference Points (TRPs)
A Target Reference Point (TRP) corresponds to a state of a fishery and/or a resource which is considered desirable and at which fishery management aims. In most cases, a TRP will be expressed in a level of desirable output from a fishery (e.g., related to catch) and will correspond to an explicit objective of the fishery. As mentioned above, MSY (and FMSY) have been considered as TRPs for decades and the dangers of that strategy have been clearly indicated by the scientific community. FMAX, corresponding to the maximum yield per recruit is an even less precautionary target reference point disregarding the risk of recruitment overfishing. Other TRPs may be used which would aim at conserving higher levels of biomass and at reducing the risk of overfishing. These are, for instance, F2/3 msy (aiming at an annual catch of 2/3 of the MSY), FMBP (where the stock is maintained at its level of Maximum Biological Production), and F0.1 (where marginal yield is 10% of the marginal yield of the virgin stock).
26Ad hoc Working Group on Reference Points established by the UN Conference on Straddling Fish Stocks and Highly Migratory Fish Stocks in New York, in March 1994 (cf. Annex 3)
27Understood by all States as the highest level of withdrawal from the resource (and fishing intensity) allowed by the 1982 Convention. Understood by some States as the recommended target level of development
When a target reference point is reached during a development process, management action should aim at maintaining the fishery system at its level, e.g., through establishment of total allowable catches and quotas or through effort controls (see below the section on Precautionary Use of RPs).
Limit Reference Points (LRPs)
A limit Reference Point (LRP) indicates a state of a fishery and/or a resource which is not considered desirable. Fishery development should be stopped before reaching it and the risk of inadvertently “crossing” the limit should be very low. Limits are usually expressed in biological terms (e.g., minimum spawning biomass required) but could be expressed in economic terms also (e.g., minimum profitability) even though this does not seem to have been done yet. Biological LRPs have a conservation function and are particularly required in a precautionary approach to set the constraints within which the management strategy must operate (Rosenberg and Restrepo, 1995). These LRPs aim, in particular at conserving an appropriate reproductive potential and at avoiding recruitment overfishing. The most important LRPs developed during the last decade are related to the stock-recruitment relationship (Sissenwine and Shepherd, 1987; Rosenberg and Restrepo, 1995; Garcia, in press). LRPs can also be expressed in terms of mortality or biomass limits (see Caddy and Mahon, 1995; Rosenberg and Restrepo, 1995).
A common way to specify LRPs is to express them as a percentage of the virgin biomass (B0) below which the stock should not be driven. A typical value often referred to is 20% B0. ICES has adopted the concept of Minimum Biological Acceptable Level (MBAL) defined, for each stock, as the level below which the recruitment has a 50% chance of falling below the critical level beyond which it will decrease as a function of stock size. MBAL could also be the level at which residual spawning biomass has a 50% chance of falling below the established 20% B0safe limit. In practice, these points are not easy to establish and may have fairly large confidence limits. Garcia (in press) describes a methodology to reflect a precautionary approach to tropical shrimp management, based on these concepts, in data-poor situations.
When a LRP is reached, management action should severely curtail or stop fishery development, as appropriate, and corrective action should be taken. In case overfishing has occurred, stock rehabilitation programmes should consider the LRP that would have been adopted for a healthy resource as a very minimum rebuilding target to be reached before the rebuilding measures are relaxed or the fishery is re-opened. An example is given by the rebuilding strategy adopted for the Southeast Australian stock of orange roughly (Hoplostethus atlanticus) following heavy overfishing between the late 1980s and the early 1990s. The Australian Fisheries Management Authority has endorsed, starting in 1995, a strategy to base Total Allowable Catches (TACs) with a view to ensure a 50% probability that the stock is at or above 30% of the spawning biomass present at the beginning of the fishery (Phillips and Rayns, 1995). This latter figure will be used, first, as a rebuilding target and, as soon as it is reached (in 2004 according to forecasts), as an LRP.
Precautionary Use of RPs and Threshold Reference Points (ThRPs)
Two major sources of bad performance in a reference points system will be examined below: (a) the accuracy and precision with which the RPs are determined, and (b) their adequation to the fishery system dynamics.
First, because of the uncertainty inherent in their determination, reference points should preferably relate to probabilities28 (e.g., specifying both their central value and confidence limits). This uncertainty as well as the uncertainty in the current value of the fishing mortality or stock biomass, imply a certain probability that these RPs be “missed”. For example, management regimes using MSY or FMSY as TRP will meet the objective only on average, with 50% chances of a slight “overfishing” or “underfishing”, in case of a normal distribution of probabilities. Assuming full control of the fishery, the seriousness of the “statistical” vagaries around the objective will depend on the breadth of confidence limits of the TRP estimate and the potential consequences of a exceeding the target with a certain frequency and to a certain extent. If these consequences appear unacceptable, a more precautionary approach will be needed.
Second, the fishery system has its own dynamics and fishing fleets have a high level of inertia (resistance to change), due to various financial, technical, cultural and administrative reasons. As a consequence, stopping their evolution and expansion and reversing or only modifying historical trends are not trivial tasks and may require time in addition to political will and incentives. Similarly, the life parameters of long-lived target species (e.g., low natural mortality and fecundity, late maturation and slow growth) are such that reversing resource trends and promoting their recovery once depleted may require some luck (on the environmental side) and some time. There is therefore a risk that, having reached a TRP or approached a LRP, in the course of a dynamic development process, it takes too long to effectively stop the fishery's evolution in this desirable situation, overshooting the target and, possibly, crossing the limit. As a consequence, more precautionary reference points and decision rules might be required in order to avoid or reduce the need for costly corrective action and to limit the amplitude of the oscillations of the fishery around its target and limits.
Two solutions are generally offered to deal with both of these problems: (a) choosing more precautionary references, and (b) using the references in a more precautionary way.
Firstly, it is possible to select different reference points based on the level of precaution desired, or risk considered as acceptable, as shown in the two preceding sections, and this is usually achieved at the expense of foregoing some potential economic benefits. It is self-evident that selecting F0.1 or F2/3 MSY as TRPs instead of FMSY, for instance, is sufficient to reduce the risk of overfishing. Similarly, choosing 20% of the virgin stock spawning biomass as a LRP is less precautionary than putting this limit at 30%29. In addition, some reference points can be used either as TRP or LRP depending on the level of precaution to be ensured. In principle, trying to avoid reaching a reference point (i.e., using as a limit) instead of trying to meet it on average (e.g., using it as a target) should reduce the probability to go beyond it. It is for this reason that Fmsy, which has been considered as a target for decades, is now proposed as a LRP, as a minimum international standard, or as a minimum target for stock rebuilding strategies (cf. Annex 5, paragraphs 1 and 16), illustrating the shift of contemporary scientific advice towards more precautionary strategies. One could select F2/3MSY as a TRP because of its a priori better performance in terms of risk to overfish and this strategy could be as precautionary as using FMSY as a LRP. In practice, the two references could be indeed used together, e.g., F2/3MSY as a target and BMSY as a limit.
28For example, a “Minimum Biological Acceptable Limit” (MBAL), related to recruitment or reproductive biomass would be defined as a level beyond which the recruitment has a 50% chance to fall below a critical level (Rmax for instance or Rmean) or the residual spawning biomass (escapement) has a 50% chance to fall below 20% of the virgin stock spawning biomass
29An example of such conservative setting of biological limits is given by the Revised Management Procedure of the International Whaling Commission (IWC) which sets the lower stock limit at 54% of the carrying capacity, a level sometimes considered as excessively conservative (Kirkwood and Smith, 1995)
Secondly, it is possible to keep the same RPs, using them differently. The probability to inadvertently “cross” a TRP when aiming strictly at it, is 50%. A different and more precautionary probability could, however, be in-built in the related decision-rule, e.g. by deciding that annual fishing mortality should not be allowed to exceed the TRP value more than 10% of the time instead of 50% of the time, or by leaving the LRP value at 20% of the virgin stock but agreeing that the acceptable probability to exceed the limit should be 25% and not 50%. These results could indeed only be obtained by fishing at a level somewhat lower than otherwise possible, on average, and this second solution is therefore equivalent to replacing the reference point by a more precautionary one (see Figure 2). Similarly, Caddy and Mahon (1995) stress that the lower the precision of the mortality estimates (e.g., their coefficient of variation), the lower the “safe” target fishing level for a given level of risk.
Precaution will be ensured by combining TRPs and LRPs which will most often refer to different control or status variables of the fishery system. For instance, a TRP might be established in terms of a proportion of MSY (e.g., two thirds of MSY) and used simultaneously to LRP established in terms of spawning biomass (e.g., 20% of the virgin spawning biomass). The implication is that the manager will develop the fishery towards producing two-thirds of MSY while monitoring carefully the decreasing spawning biomass as effort increases (just as a captain would aim the vessel towards a destination while watching the depth under the vessel's keel). The manager will immediately change the fishery TRP, or the way the TRP is being approached, if the LRP is being too rapidly approached or is dangerously close (e.g., just as the captain would modify the destination or the route with its equipment to indicate a reef ahead or a rapidly decreasing depth). A non trivial consequences of this approach is that the TRPs and LRPs should be compatible (e.g., the fishing mortality at which the TRP catch is obtained should obviously be significantly lower than that at which the LRP spawning biomass could be “crossed”).
Another solution suggested in Garcia (1994a) is to use Threshold Reference Points (ThRPs). A ThRP indicates that the state of a fishery and/or a resource is approaching a TRP or a LRP and that a certain type of action (preferably agreed beforehand) is to be taken to avoid (or reduce the probability) that the TRP or LRP is accidentally exceeded. It provides an early warning when critical reference points are being approached, reducing the risk that these points (and the management objectives they materialize) be violated. Just as in high inertia computerized tankers, alarms are pre-set to be automatically triggered if the distance to other vessels or the depth under the keel falls below a pre-determined safety value. This could be done, if the cost of permanently reducing the fishing mortality (and fisheries output), as suggested above, was not considered justified in regard to the risk. Adding precaution to the management set-up but also burden, ThRPs might be necessary only for resources or situations involving the particularly high risk related to the nature of the target stocks or the type of fishery development process.
It is paradoxical, however, that ThRPs might not be usable when they would be most needed, i.e., when natural variability is high or data is scarce. Under these conditions, the confidence limits of the estimates of the current level of exploitation (e.g., in terms of fishing mortality, Fcurrent), the TRP (e.g., the target level of fishing mortality, FTRP) and the LRP (e.g., the higher limit allowed for this mortality, FLRP), might be too large to allow statistically significant discrimination between them. The precision with which the estimates can be made determine therefore the resolution of the reference points system, and the number of points that can realistically be used simultaneously (see Figure 3).
The medium-term oscillations of the resources potential and properties (e.g., on circa-decadal scales) can be a significant cause of loss of performance of management systems and of serious crashes of the resource base. Famous examples are given by the collapse of the Peruvian anchoveta stock under El Niño, in the early seventies and, possibly, the collapse of the Atlanto-Scandian herring and Canadian Cod stocks in the North Atlantic. It is difficult to give a generic prescription relating RPs to these events. Cooke (1994), stressed that in order to be useful for management, reference points should retain their validity in the face of short- and long-term fluctuations in fish stocks due to recruitment variability and other factors. For events already observed in the past, the probabilities of their occurrence should be taken into account, including through their forecasting and related adjustment of the TRP. If such probabilities are not available a fully rational approach is probably not possible but some contingency plans or other safety-net arrangements might be instituted.
Figure 2: Relation between the effectively achieved level of mortality (Fcurrent) and TRP level (FTRP) when a 50% or 10% probability to inadvertently exceed the TRP is accepted.
Figure 3: Illustration of a low variability/high resolution (top) and a high variability/low resolution reference points system.
As mentioned earlier on, preventive action is preferable but not always possible, and effective reactive capacity is important. In this respect, pre-agreed courses of action, “automatically” triggered when TRPs are reached, ThRPs are crossed, and LRPs are approached, would be particularly advisable, in particular:
when the probability of occurrence of an unwanted negative outcome is particularly high (e.g., in areas of high environmental variability such as upwellings or semi-arid climates;
for species which are at the extreme end of their geographical range of distribution or with particularly low resilience (e.g., small cetaceans, sharks, etc.), and
when the potential cost of inadvertently “breaking the rules” could be particularly high.
Management strategies and control laws
The management strategy which establishes the way by which it is planned to reach stated objectives is largely determined by these objectives (which also determine the selection of TRPs), the conservation constraints imposed on the fishery (as materialized by the selected LRPs), and the pre-agreed course of action to be taken depending on the position of the fishery in relation to the RPs system. The management strategy will state, a priori, the acceptable probability that the LRP is violated (while apparently it is not!). The related decision-rules will be case-specific, depending on the characteristics of the stock (its resilience) and the type and flexibility of the fishery. A management strategy or control law can be graphically represented and summarized as in Figure 4. Its performance in terms of satisfying the objective (meeting the TRPs) and the conservation constraints (meeting the LRPs), can be tested by simulation (Restrepo and Rosenberg, 1994).
Socio-economic reference points
Some economic TRPs are available in theory but have been rarely applied in practice, such as MEY or FMEY (the level of effort corresponding to Maximum Economic Yield) at which the fishery generates its highest rent. This reference point is usually located well below FMSY and has, therefore, better conservation properties. On the contrary, the Maximum Employment criteria (a level never defined in theory but one of the most used, at least implicitly, by “laisser faire” management strategies) implies developing fisheries well beyond FMSY, generating high risk for the resource.
The concept of socio-economic LRP does not seem to have been used or even formally proposed but they could be developed as management systems will make more explicit use of economic theory. For instance, in order to avoid having to subsidize a national fishery, a reference point could be determined, at an effort level (fleet size) where the revenue would be equal to all costs, including the cost of research, control, surveillance and enforcement, indicating the maximum acceptable fleet size or effort level.
Figure 4: Representations of management strategies. Left: Regulation of the duration of the fishing season as a function of annual recruitment (from Garcia, 1996). Right: regulation of fishing mortality as a function of the stock biomass (modified from Rosenberg and Restrepo, 1995).
A major difficulty in selecting socio-economic reference points for management, including reduction of overcapacity, resides in the task of determining the appropriate position (level of effort, or fleet capacity) corresponding to the mix of socio-economic objectives, often ill-defined, assigned to a fishery. The little success met by the concept of Optimum Yield (OY) illustrates this problem. The difficulty in confronting the socio-economic complexities of a precautionary approach to fisheries was reflected in the difficulties met by the Technical Consultation on the Precautionary Approach to Capture Fisheries (FAO, 1995) to deal properly with artisanal fisheries for which a particular reflexion is still required.
Another difficulty is in cost-benefit analysis. It should be evident that the cost of the measure should be matched by its future benefits but that calculation is not trivial and is complicated by the multiplicity of stakeholders, the diversity of their objectives and time preferences, the different implications of the so-called “future discounting” for different groups30, and the likelihood that they will effectively receive the theoretical benefits (Shotton, 1994).
To circumvent, at least partially, these difficult, pragmatic decision rules could also be established on economic grounds, related, for instance, to fishing capacity: e.g., if capacity increases faster than catches for a given number of years, then some capacity freezing action is taken. If capacity is higher than that required to take the allowable catch by more than a given percentage, then it should be reduced, etc. The selection of socio-economic decision rules and economic reference points is difficult enough in national fisheries. In management of high seas, straddling and highly migratory stocks, the difficulty is even higher owing to the divergence of economic situations of the various national stakeholders. In such a situation, the selected rules and references would have to be general enough to be acceptable to all parties and specific enough to be of practical use.
Ecosystem reference points
Ecosystem management is being recognized with increasing frequency as the necessary basis for fisheries management and the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is often cited as the champion of the ecosystem management concept. The CCAMLR convention refers to “the maintenance of ecological relationships between harvested, dependent and related species” as well as the “prevention of change or minimization of the risk of change in the marine ecosystem which are not potentially reversible”. This requirement is precautionary in nature in the sense that it requires that the integrity and essential functions of the ecosystem must be preserved as a prerequisite to fisheries sustainability. In practice, however, we do not yet know how to manage entire ecosystems. In most cases we have not yet even understood completely how they function, why and how they fluctuate, what are the structuring variables and we cannot predict the future states of the ecosystem we are exploiting. Walters (1986) stresses that “ecosystems are moving targets, with multiple potential futures that are uncertain and unpredictable. Therefore management has to be flexible, adaptive and experimental at scales compatible with the scales of critical ecosystem functions”. The recognition of this uncertainty has sometimes led, in the international debate on the precautionary approach, to replace the requirement for ecosystem management (implying control on all elements of the ecosystem) by the more specific and practical goal of conserving not only the target species but also the associated and dependant species. If the balance between ecosystem components must be maintained, minimizing by-catch or using extremely selective gear, as common sense suggests, might not be the best solution. It has been proposed, for instance, that in multi-species management, a reasonable strategy would be to exploit all species in proportion to their abundance in order to maintain the overall ecosystem structure (Garrod, 1973). This is, however, not easy to achieve without wastage of less demanded species and additional work is certainly required on this matter before objective guidance can be given.
30 Considering the major impact of discount rates, the uncertainty about their future evolution, and the likely difference between “local” and “global” rates, a key problem of establishing socio-economic reference points is that of agreeing on these rates
More research is needed to develop specific guidelines and reference points for a precautionary approach to aquatic ecosystems exploitation, related for instance to global stress indicators, resilience factors, critical habitat conditions, acceptable impacts etc. Clarification is also required on the meaning of ecosystem sustainability and on the issue “impact reversibility”. Ecosystems have a degree of natural variability and can shift from one equilibrium state to another because of natural environmental variability or human stress and under these conditions sustainability cannot mean constancy. As far as reversibility is concerned, fisheries management may be able to suppress unwanted fisheries impacts (e.g., through fleet reduction schemes, protected areas, etc.) and rebuild productivity but there is no assurance that the ecosystem could be returned exactly to its pristine state.
Some of the aims and principles of ecosystem management can be found in the management charter of CCAMLR and in the 1990 Strategy for Sustainability elaborated by IUCN. These include: minimizing conversion of critical ecosystems to “lower” conditions, compensating habitat conversion with restoration (allowing no net loss)31, maintaining ecological relationships, maintaining populations at greatest net annual increment, restoring depleted populations, minimizing risk of irreversible change in the marine ecosystem, etc. Holling (1994) maintains that ecosystems are structured by a small number of biotic and abiotic processes which organize its behaviour and that when investing in the protection of ecosystems (biodiversity), priority should be placed on maintaining these structuring variables. A useful principle could be to aim at maintaining all the fundamental components of the ecosystem (nurseries, spawning areas, feeding areas, migration routes, etc.) in order to ensure permanency of the ecosystem structure even though the abundance (or even the permanence) of some of its species components cannot be absolutely warranted. Genetic conservation guidelines, when introduced, will make matters even more complicated as management will have to meet conservation requirements at the ecosystem, biodiversity, species and genetic levels (cf. ICES. 1995).
7.4 Practical Guidelines
In most fishery systems, a progressive but systematic and decisive shift towards more risk-averse exploitation and management regimes is advisable. This implies that precautionary measures for fisheries management should be widely used as a means to avoid crises and reduce long-term costs to society. Because uncertainty is pervasive in the ocean ecosystem and fisheries, precaution should become an integral part of fishery management systems, to be applied routinely in decision making. Unnecessarily stringent and costly measures, should be avoided as they would rapidly become counter-productive by deterring fishery authorities from using the concept as widely as possible and discrediting the approach among industry.
A precautionary management strategy would need both a sufficient preventive capacity to avoid predictable problems, and enough reactive (corrective) capacity, flexibility and adaptability to ensure a safe “trial-and-error” process, as knowledge about how the system works is collected. It should recognize the uncertainties in the data and promote adaptability and flexibility of management regimes through appropriate institutions and decision-making processes. It would rely not only on expert advice but also on people's participation. As stated by Holling (1994) “effective investments in a sustainable biosphere are therefore ones that simultaneously retain and encourage the adaptive capabilities of people, of business enterprises and of nature”. In case of doubt, decisions should “err on the safe side” with due regard to the risk for the resource and the social and economic consequences.
31This concept of “compensation”, which proposes that human activities should lead to “no net loss of habitat”, implies that, if some part of a habitat must be damaged somewhere, compensation is provided somewhere else
A fishery management policy based on a reasonable interpretation of the concept of precaution should: (a) explicitly adopt the principle of sustainable development as defined by the FAO Conference (given in the introduction to this paper); (b) explicitly state a set of objectives that are compatible with this principle, and (c) adopt a precautionary approach based on the following measures:
Promotion and use of research
Promote research in support of the precautionary approach to management, e.g., research aimed at understanding better the conservation requirements of the ecosystem, biodiversity, species and genetic levels as well as research towards a better definition of management reference points, including economic ones.
Use the best scientific evidence available and, if it is not sufficient, invest in emergency research while interim management measures are taken at the level required to limit risk of irreversible damage.
Improve information systems commensurate with the level of risk, covering costs through fishing fees as required, addressing all resources, directly or indirectly affected and promoting joint research programmes in international and regional arrangements.
Experiment with management strategies and pilot development projects with the support of research, generalizing the use of Environmental Impact Assessment (EIA).
Reference points, rules and criteria
Adopt a set of objectives for the fishery and a related set of reference points (broader than the traditional MSY) and management benchmarks, and use the latter to measure the efficiency of the management system (e.g., in terms of achieving production targets, controlling fleet capacity, and maintaining spawning stock size or recruitment levels).
When alternative options are considered, adopt a risk-averse attitude, considering a priori that: (a) fisheries are likely to have a negative impact on the resource, and (b) risk of unacceptable or irreversible impact should be minimized.
Ensure that precautionary management plans specify, inter alia, the data to be collected and used for management and their precision, the methods of stock assessment, the decision rules and reference points needed for determining and initiating management measures as well as contingency measures to be taken in case of danger for the resource.
Adopt provisional reference points when data are poor or lacking, establishing them by analogy with other similar and better known fisheries and updating/revising them as additional information becomes available.
View Maximum Sustainable Yield (MSY) as a minimum international standard, ensuring that fishing mortality does not exceed the level needed to produce it and that stock biomass is maintained above it (or rebuilt at least at this level).
Adopt precautionary management reference points defined on the basis of agreed scientific procedure and models, including Target Reference Points (TRPs) and Limit Reference Points (LRPs). Because of the uncertainty inherent in their determination, these reference points should preferably be expressed in statistical terms (i.e., with a central value and a confidence interval).
Adopt action-triggering thresholds and management strategies which include pre-agreed courses of action, automatically implemented if the stock or the environment approaches or enters a critical state as defined by pre-agreed rules, criteria and reference points32.
Adopt Threshold Reference Points (ThRP) where specific conditions require added precaution, to indicate that the state of a fishery and/or a resource is approaching a TRP or a LRP and that a certain type of action (preferably agreed beforehand) is to be taken, to avoid (or reduce the probability) to accidentally go beyond the selected TRPs or LRPs.
Ensure that management action maintains the stock around the selected TRP on average (e.g., through establishment of total allowable catches and quotas or through effort controls) and that the probability of exceeding the target, and the extent by which it is exceeded, are kept at acceptable levels.
Severely curtail or stop fishery development, as appropriate, when the probability of exceeding the adopted LRP is higher than a pre-agreed level and take any corrective action deemed necessary. If the LRP is indeed exceeded, implement a stock rehabilitation programme using the LRP as a minimum rebuilding target to be reached before the rebuilding measures are relaxed or the fishery is re-opened.
Bring into force, “automatically” the set of pre-established measures, or courses of action, when a ThRP is reached particularly in cases or situations involving high risk.
Ensure that selected reference points are robust to short- and long-term fluctuations in fish stocks due to recruitment variability and other factors and that they are periodically re-assessed as new data is collected and new understanding or methods become available.
For newly discovered stocks, establish safe biological limits (in absolute or relative terms33) and threshold reference points from the onset; prohibit large scale development; limit removals, through effort and catch limitations and resource allocation schemes, to a fraction of the stock well below annual natural mortality; set-up monitoring and assessment programmes on the target and associated species.
Aim at maintaining the fundamental components of the ecosystem (nurseries, spawning areas, feeding areas, migration routes, etc.), minimizing their degradation and, where possible, re-establishing them in order to ensure permanency of the ecosystem structure and productivity mechanisms even though the abundance (or even the permanence) of some of its species components cannot be absolutely warranted.
32One of these courses of action could be a moratorium. However, if reference points are selected on a cautious basis, and monitoring produces information on a quasi-real-time basis, a range of more cost-effective alternatives should be available (seasonal or temporary closures, modification of fishing patterns, significant reduction of effort, etc.)
33That is, as a proportion of the virgin stock
Promote discussion and agreement on acceptable levels of impact (and risk) in a process that will identify trade-offs and promote transparency, particularly in relation to public opinion.
Take into account the combined stresses of fishing and environment on resources. Effort reductions may be imposed or special measures affecting fisheries taken when the stock faces unusually unfavourable environmental conditions.
Address as far as possible all combined stresses to the resource, including those imposed by non-fishing activities or related to natural fluctuations34.
Prohibit irreversible impacts as well as decrease of any population of marine species below the which ensures the greatest net annual increment of biomass (i.e., the MSY level). For overfished fisheries, an important objective should be to rebuild the stock at least to that level.
Set catch and effort levels for target species in accordance with the requirement that they do not result in unsustainable levels of mortality for both target and non-target species.
Manage fisheries in the context of integrated management of coastal areas, raising sectoral awareness about exogenous impacts on the state of the resources and on fisheries productivity.
Improve public awareness, as well as consultation of non-fishery users, taking all interests into account when developing and managing fisheries, as required in Agenda 21, improving management transparency and reporting procedures.
Improve decision-making procedures, replacing consensus decision-making by voting procedures wherever possible.
Strengthen monitoring, control and surveillance, thereby improving detection and enforcement capacity (including legal tools), raising penalties to deterrent levels, and exerting more effectively the responsibilities pertaining to the flag or the port States.
Avoid overburdening of management systems and industry by limiting the number of precautionary devices and measures implemented at all times, based on an analysis of the probability of occurrence of negative impacts of a certain magnitude, pre-agreed as part of the management scheme and reflected in appropriate reference points.
Establish safety-net arrangements (e.g., in terms of insurance, compensation, etc.) to protect the users from the consequences of exceptional hazardous occurrences.
Establish precautionary management regimes for all resources, across their whole area of distribution, whether in EEZs, in the high seas, or both (high seas, straddling and highly migratory resources).
34This means that restrictive action on fishing might be needed even when the causal mechanism is natural (e.g., related to El Niño, droughts, or other medium-term natural fluctuations)