A decision rule which, as defined by the TCPA, “specifies how preagreed management actions will respond to estimated or perceived states of nature” (FAO Govt. of Sweden 1995) is fundamental to the effective application of reference points, particularly Limit Reference Points.
There are two substantially different approaches to the application of LRPs. The first is the simpler. Fishing is unregulated until the LRP is reached, then it is stopped (e.g. Hall et al. 1988, Quinn et al. 1990). When the ecosystem recovers, fishing can begin again. This is also referred to as pulse fishing. A spatial version is the rotation of fishing effort through a series of fishing subareas in which fishing is either ‘on’ or ‘off’. The pulse fishing approach has significant implications for economic outputs of the fisheries, because production may be erratic, except in the case of spatial rotation. Furthermore, unless the ‘on’ switch is activated only at significantly higher levels of biomass than the ‘off’ switch, the fishery will hover in the vicinity of the LRP.
Alternatively, the LRP can be used as an ‘undesirable event’ whose risk of occurrence should be minimized by setting targets which are well clear of the limit. If there is an estimate of the variability associated with the reference variable used to set the LRP, then the target value for the reference variable can be defined as the value at which there is an acceptably small probability that the LRP will be reached. Used in this way, the LRP is an emergency control point, with a low (and known) probability of being invoked, rather than a means of ongoing control. An example of this situation was shown in Figure 9 using Fmsy as the limit to be avoided. The relationship between target F and limit Fmsy, in the simplest context, is defined by the variability of the F estimate. With this latter approach there is no need for an arbitrary conservative value for target fishing mortality such as 2/3Fmsy, although of course, the value for the limiting probability (0.1, 0.02) may be arbitrarily chosen.
In establishing the decision rule or control law for implementation of an LRP, it may be most effective to reduce F to a level that is inversely proportional to the extent to which the TRP has been exceeded.
In addition to TRPs defined so as to avoid LRPs, there may be other desirable attributes of the fishery which can be targeted within the constraints of the LRP. Thus any well managed fishery will use a combination of TRPs and LRPs. In well studied fisheries with good historical data it is likely that there will be at least one model based TRP, and possibly several LRPs; some model-based, others empirical. For little studied fisheries, it may be necessary to adopt TRPs and LRPs, which will be simple criteria based on experience derived from other similar fisheries or from generalisations about many fisheries, such as the %SPR values suggested by Mace (1994) or Hall et al. (1988).
Reference points which are qualitative or semi-quantitative in nature can also be incorporated within a “Set of Rules” which determine how the fishery is to be managed. These may specify the management response to (e.g.), a high discard rate of protected species. Again, if one or more of these rules are broken, a pre-negotiated management response should automatically be initiated. One example might be the temporary ban on fishing by a given fleet in a prespecified area when discards or by-catch limits have been exceeded. Another example of a trigger might be when the proportion of immature fish in the catch exceeds a preset percentage.
The TRPs and LRPs can be incorporated into a set of management criteria (e.g. Table 5). The development of such sets of rules will be most effective if it is based on a sequence of questions and actions such as is shown in Figure 14. If one or more of the latter criteria are infringed, a preset management response is triggered. One such set of criteria has apparently been developed for the Eastern Bering Sea/Gulf of Alaska groundfish fishery and includes: a threshold biomass set at 20% of the virgin stock biomass; a maximum fishing mortality rate set at 30% of the relative SSB/R; and a maximum fishing mortality rate set at 80% of the M value for the species concerned.
Figure 14. Sequencing of fishery management questions with a priority on sustainability gives habitat and ecosystem conservation highest priority, puts resource conservation next, and ends with issues of yield optimisation.
For short-lived species, e.g. some squid or anchovy resources, for which stock size may only become known during the fishing season, a set of rules may have to be invoked in sequence during the same season (Caddy 1994, Basson and Beddington 1993, Butterworth et al. 1993). For squid, effort (number of licences) or TAC may be set at the beginning of the season to aim for a target level of ‘proportional escapement to spawning’, an agreed percentage of that surviving for the same number of recruits with no fishing, which would provide a safe level of absolute escapement, provided that recruitment is in the normal range. The artisanal effort can be fine-tuned later in the season through a variable date of closure of the fishery, if real-time measures of accumulated catches and/or surveys of abundance, indicate that either changes in fishing patterns or very low recruitment may result in escapement to spawning dropping below the preset threshold level.
The means of verification (MOV) and objectively verifiable indicators (OVIs) for establishing the current status of the fishery must be clearly specified. The MOV will generally be based on the same models and methods used to derive the reference points. The frequency with which the status of a fishery must be checked will be dependent on the life history of the species. For most stocks in which the age range of fish in the catch is 3–10 years, an annual time-frame will be appropriate. For long-lived species such as whales, redfish in the North Atlantic and orange roughy in the area of Australia and New Zealand, where the mean age of exploited individuals may be > 10 or even 20 years, it should only be necessary to review stock status at intervals of several years. In contrast, for short-lived, or annual species, such as small pelagic fishes, or squids, real-time evaluation of stock status may be required (Basson and Beddington 1993, Butterworth et al. 1993).
The review and revision of reference points may be desirable or necessary for various reasons:
- Management objectives may change (e.g. the need to conserve reef fish for tourism instead of for commercial fishing only, as formerly);
- A more precautionary approach may be needed, judged from the results of management or stock size trends.
- There may be conceptual advances regarding appropriate management of resources (e.g. inclusion of ecosystem criteria, or measures of ecosystem ‘health’);
- There may be methodological improvements relating to existing Reference Points (e.g. maximum likelihood estimators of S-R relationships) which change our perception of the RP being used; and
- New data may become available for incorporation (e.g. more data points for a S-R relationship);
The first three require renegotiation of the “Set of rules” for management. The fourth requires renegotiation of the MOV and possibly the OVI, the last is automatic whenever new data become available.
The growing emphasis on non-harvest uses of the resource may be one reason for modifying the management objectives of fishing. This is increasing in frequency as a result of the interests of constituencies outside the fishery sector. For multi-user resources there is a considerable danger of frequent changes in objectives, which can lead to time-consuming negotiations, and in the event of disagreement between the parties concerned, a management vacuum and the danger of overexploitation. If negotiations are protracted, management should provide for the use of a precautionary approach in the interim.
To know where the stock is in relation to a Reference Point requires regular monitoring of the relevant reference variables (OVIs) and also a realistic appreciation of the precision with which these variables can be estimated. The current value of the chosen reference variable(s), such as the fishing mortality rate, stock biomass, and yield (Fig. 3) can be referred to as Fnow, Bnow, and Ynow. These estimates should be accompanied by at least a rough estimate of the likely magnitude and direction of the error of estimation.
Systems for collecting and storing fishery information from all participants and carrying out fisheries surveys and research, are integral parts of establishing whether management targets are being met, and of evaluating the effectiveness and impact of management measures. As a condition for receiving a commercial fishing licence, fishermen should be obliged to provide accurate information on their location, type and time of catches, and fishing effort. This information can be gathered through log book systems, by port interviews with fishery officers, by on-board observers, radio reporting and at-sea inspection. and possibly in the future, through black box monitoring via satellite of the position of fishing vessels and the operation of their mechanical equipment. Likely biases, errors and misreporting of catches will need to be estimated under a precautionary management framework.
Management actions for a new fishery should ideally follow the sequence:
Some items in the above sequence (e.g. e, f, and g) should be under regular review, but renegotiations to revise them will be difficult to achieve for a multi-participatory fishery. Others (e.g. b, h and i) will need to be reviewed at intervals of several years as conditions change, and items a, c, j, and k will need to be reviewed yearly if benefit from a resource is to be optimal, and the probabilities of overshooting the chosen TRP, or entering a dangerous zone as indicated by a LRP, are to be minimized.
There will rarely be new fisheries that do not affect existing marine harvests, where the sequence a-k above can be applied uninfluenced by an existing or associated fishery. New objectives in a fishery are almost always superimposed on or replace old ones. Thus the relative emphasis on the elements in the above sequence may vary depending on what is already in place.
Regardless of what sequence of actions is considered to be most appropriate for the fishery in question, the process should be documented in a way which will facilitate input and review by all interested parties. The macro-decisions should also be addressed within a framework, such as shown in Fig. 15, which requires that management decisions be taken by agreement even when there is a need to acquire more information for long-term management.
Figure 15. A macro-decision sequence for fishery management which emphasises the need for agreement, even when the fullest desirable information may not yet be available. Lack of information may be a short-term condition, while data collection and analysis is in progress, or a long-term condition due to lack of funds and expertise. In either case management must proceed using the best available knowledge.
As specified under the 1982 Convention, the above activities need to be carried out in cooperation by all parties, with exchange and pooling of data as preconditions for any scientific management of a shared, straddling or highly migratory stock.
| COASTAL STATES “…SHALL SEEK, EITHER DIRECTLY OR THROUGH APPROPRIATE SUBREGIONAL OR REGIONAL ORGANIZATIONS, TO AGREE UPON THE MEASURES NECESSARY TO CO-ORDINATE AND ENSURE THE CONSERVATION AND DEVELOPMENT OF [SHARED] STOCKS…” |
| The 1982 Convention on the Law of the Sea |
Traditionally, the assessment and management of fish stocks has been a two-tier process: scientists present assessments in the form of one or more catch or fishing mortality levels aimed at maintaining or rebuilding stocks, and the managers (Commissioners or representatives of the Ministers of Fisheries of the countries concerned) make the final decisions on the level of harvesting to be followed. While fishery scientists are best qualified to provide quantitative advice on the risk associated with any management strategy, they cannot be expected to advise on the acceptability of a particular risk (Hilborn et al. 1993); similarly, managers should have a clear understanding of the risks of particular management actions.
In some fishery management systems scientists have noted that if they adopt the statistically correct procedure of providing a range of possible values for any TRP, the managers usually select a value towards the upper, more risk-prone, level of the range. This generalization, and the high degree of uncertainty inherent in the assessment process, has often led to scientific advice being presented to decision-makers as one, or several, explicit values, without reference to the uncertainty of the estimates. This practice of providing estimates without reference to their uncertainty means that scientists have preempted the responsibility of managers for deciding upon an acceptable level of risk. It has thus given management a false sense of the precision of the assessment process, and underplayed the risks of stock decline due to uncertainty in the advice. It has probably also reduced the imperative for managers and decision makers to confront uncertainty, and to take the necessary steps to address it with industry, participants and fishers.
The role of the stock assessment expert in the fishery management system should be to provide options based on the best available information, with associated estimates of uncertainty, and where possible risk. They should avoid ‘second guessing’ the management process, or adjusting their advice to compensate for perceived inadequacies in management.
The choice of a control system or management strategy for fishery management will depend largely upon the set of reference points selected. There are usually several ways, however, of regulating the fishery towards a desired Reference Point (Beddington and Rettig 1984). The open access nature of most marine fisheries has been the main cause of stock depletion, loss of biodiversity and loss of economic earnings, which together have adversely impacted fishing communities.
Management measures may be envisaged as either, a) Input controls, such as limitations on size and fishing power of vessels and gear, restrictions on credit, limited licence or limited access schemes, or b) Output controls, such as restrictions on the characteristics of the catch (size, species composition), the total amount of fish harvested annually by the fleet (Total Allowable Catches), by individual vessels (Individual Quota Schemes), or controls by taxes on landings. In some managements systems, individual vessel or fishermen's quotas may be transferable (ITQs) through the creation of a market for access rights. As for landing taxes this market in rights may be used by management or the State to extract revenue from the fishery.
Three distinct management strategies have been proposed that explicitly or implicitly use target reference points: constant catch, constant effort and constant escapement. These strategies can be combined with threshold values to drastically reduce exploitation when stocks are believed to be in danger of overexploitation (Fig. 16).
Figure 16: Showing the idealized relationship between catch and escapement under wide variations of stock abundance for four management strategies: 1) a constant annual quota with threshold at low abundance when fishing is not allowed; 2) management under a constant exploitation rate; 3) again, a constant effort control scenario with a threshold if natural variation results in very low stock sizes, 4) A constant escapement strategy as attempted for some salmonid and squid stocks.
Catch quotas may be used to achieve a TRP and may be variable or constant. For stocks with wide fluctuations in abundance (as for many pelagic resources), a constant catch quota referred to here as MCY will result in constantly varying rates of exploitation (Sissenwine 1978). Unless it is set at a very low level, a significant probability of overexploitation always exists in low abundance years (Fig. 17). If information is scarce or uncertain, then a very low, fixed quota, using TRP criteria developed with reference to a preset probability of Fmsy being exceeded, could be followed as discussed above. One alternative here could be to definitively allocate this low MCY as ITQs, agreeing on supplementary and temporary allocations only in very favourable years.
Allocating a low MCY could also be useful in situations where maintaining a moderately high stock size is essential, as for stocks also important to sports fishing, tourism, subsistence fishermen, or for straddling stocks which provide a livelihood to communities of the rural poor. Here management could adopt a constant, low, annual quota and a cutoff point dictated by one or a series of LRPs which measure when stock size is critical. At that point the fishery should be temporarily interrupted until unambiguous signs of recovery are seen (Fig. 16). Management with such a cutoff point was successfully applied to herring stocks on the West Coast of Canada (which are highly vulnerable to overfishing or pre-spawning congregations) following a moratorium for stock rebuilding after earlier depletion by an open access fishery.
Figure 17: Illustration of the constant catch fishery management strategy for a stock which fluctuates. Constant catch must leave enough spawning stock biomass at the lowest stock biomass level.
Variable quotas tend to lag behind the actual variations in recruitment (and still later, stock size) by one or several years. Particularly as good year classes are being fished up, a quota that would have corresponded to F0.1 or even lower levels when the peak year class was entering the fishery, now corresponds to Fmsy or even higher levels. There is a marked reluctance by industry to accept a sudden drop in supply under these circumstances. In the North Atlantic, management to date has been largely based on TACs, but there is growing evidence that advice on desirable catch levels has become less reliable due to unrecorded catch and high discards (FAO 1992a). The TAC advised by scientists, that TAC finally agreed after political decision making, and the actual catches taken, have tended to increase in sequence (Angel et al. 1993).
One of the mandatory requirements for quota management under open access, even at apparently reasonable F levels such as F0.1 , is the need to ensure accurate, real-time estimates of catch, age composition and standardized fishing effort. The fact that many conservatively-targeted quota management systems have failed, even for proprietary resources of EEZs, should prompt a re-examination of all facets of the management procedure. This review should begin from considerations of statistical validity of the sampling scheme, the possibility of misreporting, the appropriate population models used, and should involve sensitivity analysis of the parameter values entered in them. The degree to which quotas chosen correspond to the projected fishing mortality rate has been questioned for some developed country fisheries. Even more serious in their effect is the degree to which subsequent catches can be maintained within the quotas allocated, or whether politicoeconomic considerations will be allowed to ‘stretch’ the quotas proposed by fishery scientists.
A number of authors have shown the advantages of fixing the level of fishing effort as opposed to fixing catch quotas (e.g. Hannesson 1993) (Fig. 16). Beddington and May (1977) noted that with a constant catch management strategy, environmental perturbations will cause more serious departures from equilibrium conditions than when a constant effort strategy is followed. This was also the conclusion of Reeves (1974), who found by simulation, that under recruitment variation, an effort limit produces higher catch rates than a fixed catch quota, even if the latter corresponds to the same Reference Point defined in terms of fishing effort.
A constant effort strategy requires that fishing effort be controlled to that corresponding to a target F value; usually by limited entry. Early criticisms of this approach were that increases in catchability due to learning by skippers and due to technological improvements to boats and gear, both lead to ‘creeping’ increases in fleet fishing power. Another disadvantage, seen in the early optimistic days of quota control, was that under effort control, catches would vary more from year to year than with TAC management, but we should note that this is still more desirable than stock collapse. Other more valid objections relate to pelagic stocks such as herring where vulnerability to fishing goes up at low stock sizes, so that the fishery can enter an unstable area at low stock sizes unless some limiting LRP is applied, as for the constant escapement strategy mentioned above.
The objections to effort control as a management procedure need to be reassessed in the light of recent failures of quota control. Effort control measures have the following virtue, especially for poorly documented straddling stocks: they provide a more stable rate of exploitation and do not require real-time enumeration of all catches. Thus there is less need for drastic year-to-year renegotiation of management targets, than is the case under quota control.
A constant escapement or spawning biomass-based policy has generally been shown to provide the highest sustainable yields. Salmon management has classically been based on attempting to achieve a minimum escapement to spawning, and many such fisheries in western North America aim for fixed escapement objectives. This type of management approach has also been used for squid fishery management in the south Atlantic within exclusive management control. Such a management approach is compatible with the spawning biomass Reference Points described earlier, but is likely to require too high a level of information input, and real time monitoring and control, for most of the open sea resources considered here.
In many instances, despite the availability of useful and safe reference points, management has failed to achieve sustainability owing to problems with the institutional arrangements for reviewing, and/or modifying advice in the context of other considerations. Although many of these institutional considerations are not as well quantified as the assessment advice, they can nonetheless be formally stated and accommodated in deriving the final set of TRPs and LRPs from which management will be implemented.
| “… FISHERIES DEVELOPMENT PROJECTS NEED TO EMPHASIZE ORGANIZATIONAL RATHER THAN TECHNICAL FACTORS IN PROMOTING SOCIALLY AND BIOLOGICALLY SUSTAINABLE DEVELOPMENT” |
| Bailey and Jentoft 1990 |
The mechanism by which the above process is achieved must have an institutional framework. It must include a means of consultation with the stakeholders and other interested parties, and a decision-making forum. However, once an approach has been adopted and a set of rules agreed upon, ad hoc short-term decision-making should be kept to a minimum. Short-term expediency should not, except in extreme circumstances, be allowed to interfere with the long-term management objectives which have been established by consensus, within the framework of a medium to long-term consensus fisheries management plan. The routine management and surveillance capability, and the statistical sampling needed to generate objective ongoing information on stock status, must operate largely autonomously from socio-economic pressures. As previously stressed, the response to an infringement of an LRP must also be automatic. Once the consensus of industry has been achieved, implementation of management measures agreed to should be immune, to the fullest extent possible, from ‘interference’ by the resource users and their representatives.
A transition from a largely ‘biological approach’ to a ‘bioeconomic approach’ is desirable, and will draw in fishery system components formerly considered extrinsic to the technical advisory process (e.g., fishery enforcement, fishery associations, the private sector, etc.) to the arena of technical analysis (Anderson 1987). In section 2 we referred to some analytical approaches to reconciling inputs from various sources. This inevitably changes the focus from ‘… open-access equilibrium and a narrowly defined efficiency point, to a comparison of a regulated equilibrium and a more broadly defined efficiency point’ (Anderson 1987).
A review of several examples of how, in practice, information flows, advice is structured, and decisions are taken in fishery management systems, suggests that there has been a ‘Standard Management Format’ for fisheries bodies but that the current trend is away from that format (Appendix III). In the Standard Format there are at least two bodies arranged in a hierarchical fashion. One is a group of resource scientists developing technical advice and providing it, possibly via a technical review body, to a dominant Management Authority or Body (e.g. the Minister or a group of senior civil servants) which draws its authority to act from the State or States involved which have set up the management system. This Authority negotiates with the fishing industry and decides if and how the resource shares advised by the technical body should be modified in the light of current requirements of the stakeholders in the fishery. It usually has the power to overturn advice from the resource advisors, based on perceived, often short-term considerations, in which the current well-being of the stockholders plays a major role.
| THE INABILITY TO MEET THE CONSERVATION OBJECTIVES, IN PART DUE TO SHORT TERM TRADE-OFFS IN SUPPORT OF SOCIAL AND ECONOMIC OBJECTIVES, HAS IN THE LONGER TERM UNDERMINED THE SUSTAINABILITY OF THE COMMERCIAL FISHERY AND THE FISHING COMMUNITIES. |
| Angel et al. 1994 |
With the Standard Management Format, the resource assessment group operates under terms of reference provided by the dominant management body. These, if formulated, are usually defined in terms of one, or several, alternative targets for exploitation. Under this format, decisions are often left to the resource assessment group as to:
- The type and quality of relevant or admissible data,
- The mathematical models to use,
- The mode of fitting the models and the statistical limits acceptable,
- The interpretation of the current status of the stock and its future potential for replenishment.
The assessment group may be requested to suggest management targets and new target reference points for the approval of the dominant management body. Broad issues such as ecological considerations extrinsic to the (usually single) species being assessed may be addressed by this group, but until recently have generally been considered outside the formal management advisory process. This vacuum of concern is currently becoming a preoccupation of society at large, outside the fisheries sector.
The Dominant Management Body is appointed by the State or States, and its member(s) often have a different mix of professional competence from the assessment group. They are usually government employees; often senior civil servants, economists, and directors of resource institutes. They receive inputs from representatives of fishers and the fishing industry, often via a formal consultative procedure. Very occasionally, non-exploitative interests are represented, e.g. fish consumers, academics, and conservationists. Given that this group has the duty of responding to pressures from fishers and the fishing industry, who inevitably have legitimate concerns with negative socio-economic impacts of effort restrictions on coastal communities, it is influenced by the desire to at least maintain allocations for fishing at current levels, and are likely to resist cuts in exploitation rate.
An argument can be made, which is consistent with the ideas presented in this paper, that the Standard Format is an appropriate one at low to moderate levels of fishing, but is less effective in dealing with situations where formal limits to exploitation need to be erected and restrictions or reductions in the level of exploitation justified.
Other management frameworks may be required to ensure that day-to-day decisions on management by the management body which has been given authority, are constrained by a “Management Plan or Procedure” or by a Fishery Convention (see for example that of CCAMLR). These documents should provide criteria for allowable action, but usually lack an independent review body that sets up LRPs and ensures that they are not infringed. Such a hypothetical review body is referred to here as the ‘Committee for Limits and Standards’ (CLS). The CLS would not replace the Standard Fisheries Management Authority (SFMA) and its resource assessment advisory group, but would provide a review mechanism, with experts from outside the government organization responsible for fisheries, to ensure that the overall limits for continued resource productivity are not overstepped (Table 6). Such a mechanism has recently been instituted in Atlantic Canada, where the Commission for Conservation of Fishery Resources (CCFR) performs such a role: a body with members also drawn from outside the federal fisheries department reporting directly to the Minister of Fisheries.
It is useful to note that other successful governmental mechanisms of government with a hierarchical structure for decision-making also perform similar independent review and appeal functions involving a system of checks and balances (often referred to as a ‘watchdog’ function). The role of the Supreme Court in some democracies checks the legitimacy of government action against the system of laws in place or against a formal constitution. In some countries, the Central Bank is expected to set interest rates and control money supply, largely independent of immediate government policies, in order, amongst other roles, to control inflation. Both of these mechanisms are staffed by top expertise, and operate ‘at the limits’, without becoming involved in the routine operations of the courts, or the day-to-day running of the government or economy, respectively. Fisheries management is currently coming to be viewed as a high risk activity. Interestingly enough, following massive financial losses to commercial banks engaged in high risk ‘futures’ trading (where the investor attempts to predict future prices of a commodity), ‘watchdog’ functions are being recommended for merchant banks.
It is in this context that the hypothetical CLS is viewed as operating: establishing the limits to safe exploitation, overseeing short-term management measures, and offering advice, on request, on technical issues related to management, but not replacing the role of the SFMA and its assessment advisory group in routine management (Table 7).
The division of responsibility between the CLS and SFMA is suggested in Table 8. The technical and operational roles inherent in the ‘Standard Management Model’ being are divided the different bodies: for the CLS, the objective is to define dangerous stock conditions and protect the stock from the results of human error; and for the SFMA, it is to develop practical management measures that do not infringe limits set by the CLS. Both groups would include a wide and different, though overlapping, range of technical competence, and may each have their technical working groups or advisory experts.
There is usually considerable reluctance to establish new structures and committees, particularly at the national level, and especially in developing countries with limited resources. Thus it is important to examine ways in which the above structure can be accommodated within existing organizations. Most coastal States have legislative provision for the SFMA. A Fisheries Department usually serves both as the SFMA and its technical group, while a Fishery Advisory Committee from outside the Fisheries Department often serves to advise the Minister based on independent technical inputs from its own representatives or from non-governmental institutions.
The recent emphasis on sustainable development and environment has led several coastal States to consider the establishment of transdisciplinary bodies for integrated coastal zone management (e.g. Towle et al. 1991). Such a body might also function as a Committee on Limits and Standards, since fisheries would inevitably fall within its broader ambit. Therefore, in planning for the broader environmental needs of sustainable development and resource use, in the coastal environment, it should be possible to also provide for the function of the proposed CLS.
