Science and Decision-Making in Fisheries Regulation
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SCIENCE AND DECISION-MAKING IN FISHERIES REGULATION by Ray J.H. Beverton International Federation of Institutes for Advanced Study (IFIAS-ABC) 55 Sandown Avenue Swindon, Wilts SN3 1 00 United Kingdom Resumen Se comentan algunos de los problemas que se encuentran al tratar de entender mejor la relación entre la ciencia y la toma de decisiones en la explotación de recursos pesqueros. Los conceptos sobre rendimiento máximo sostenible, la teoría del rendimiento de equilibrio y la ordenación pesquera se consideran como aspectos fundamentales en la comunicación entre estos dos sectores y se discuten en esta perspectiva. Se hace referencia en los distintos factores que deben ser tomados en cuenta para poder hacer un enfoque socio-económico integral al sistema pesquero y se intenta una primera clasificación del riesgo de explotación. Se discuten también algunas de las implicaciones que deben ser tenidas en cuenta en el proceso de toma de decisiones. INTRODUCTION Having been for a decade or so away from the mainstream of fisheries research, I am not infrequently asked what I make of events during that time (i.e. from 1965 to 1980, give or take a year or so). Sometimes the question is accompanied by the comment you will no doubt have noticed that the same old problems are still with us. It is, indeed, a somewhat sobering thought that the theme of this Conference - except for its geographical slant and the word ‘neritic’- could well have been that of an ICES Special Meeting as far back as the 1930's. As is true of so much human endeavour, progress in fisheries research has been like the curate's egg - good, in parts. Our understanding of some aspects of the ecological basis of fish populations has advanced greatly, as have our techniques for sampling and analysis of data. No less spectacular have been the theoretical developments, and I scan modern fisheries mathematics with awe and a large degree of incomprehension. The accumulating stock/recruitment data have provided a bonanza for the curve-fitters, an activity which has attracted some justified scepticism. Nevertheless, we really do know a great deal more about the relationship between parent and progeny in fish populations than when Sidney Holt and I at Lowestoft and Bill Ricker at Nanaimo were trying to extract the last ounce of information from the limited data we then had. The high variability of S/R data may be ‘noise’ to the statistician but to the biologist it should hold the secret to much of what we want to know about fisheries - if he knows where and how to look for it. The fact remains, however, that we still have only clues here and there as to the environmental causes of recruitment fluctuations, and even less of the natural compensatory mechanisms, if any, in the major marine fish populations. 351 Perhaps these “failures”, if that is a correct description, have been at least partly responsible for what seems to be to have been a more disturbing development in the last decade. I refer to the crisis of confidence which has built up in some quarters concerning the fundamental validity of the scientific basis for fisheries management. These doubts have been eloquently expressed by some of the leading fisheries scientists of my, as well as the younger, generation. The concept of maximum sustainable yield (MSY) as the objective of management has come in for particularly strong criticism (e.g. Larkin, 1977); Holt (1980) goes further, challenging the whole idea that man can “manage” living marine resources on scientific principles. In view of the surprises and disappointments of recent years this reaction is understandable. Nature has a way of giving us embarrassing reminders of how easily our best laid plans can come unstuck; fisheries is no exception, especially when some of our plans have not been that well laid. But that does not mean for a moment that a rational approach to the utilisation of our fish resources is not possible or necessary, or that science does not have a major role to play. Whatever the frailties in fisheries science and management that may have been exposed by recent events, the destructive power of unrestrained modern fishing operations, backed by economic and political pressure, has become only too painfully obvious. Not the least of the problems that are still with us, perhaps even more acutely, is that of communicating scientific assessments of fisheries to the decision-makers. This paper is offered as a small contribution towards finding a way forward in this grey area, which necessarily involves the socio-economic dimension and the treatment of uncertainty and risk. It extends certain concepts I put forward in the Santiago seminar of August 1982 co-sponsored by FAO and IOC (Beverton, in press); and draws in particular on the chapter on the Societal Value of an El Niño forecast, by Michael Glantz, in Resource and Environmental Uncertainty; John Wiley, 1981. MANAGEMENT AND MSY It is frequently claimed that the concepts of MSY and equilibrium yield theory are obsolete. This issue is central to the communication between science and decision-making, as is the concept of “management” of fisheries: it is worth checking on where we stand, and return later. In my time we did not use the word “management” nor the term MSY. I was brought up in the Michael Graham school of “rational exploitation”. By this was meant harvesting (the agricultural analogy was intended) the natural productivity of the fish stocks in a sensible way, i.e. letting fish grow to a reasonable size before catching them, and not making the future worse by wasting time and money fishing unnecessarily hard. In view of the intrinsic tendency to the contrary in any common property resource, we thought primarily of “regulation”, i.e. a means of restraining this otherwise inevitable drift of the fishery towards self-immolation, rather than the more positive and comprehensive control conjured up by the word “management”. The equilibrium yield theory as Sidney Holt and I developed it, both as yield per recruit and as absolute yield incorporating a stock-recruitment relationship, was intended to formalise this principle of fisheries regulation and provided a basis for action. Fig. 1 illustrates this approach. We worked on the premise that if the equilibrium yield curve had a maximum (at Fmax) and if the present F1 was manifestly higher than that, then more of the potential natural productivity of each cohort would be utilised at less cost if F were reduced to Fmax and kept there, or thereabouts. 352 Fig. 1. Hypothetical illustration of relative improvement by regulation of fishing effort, F being reduced from F1 to Fmax. Depending on how that reduction was brought about so, we supposed, would the long-term economic situation be improved (by most criteria). Future recruitment, and hence catches, would of course continue to fluctuate, as they always had, for reasons beyond man's control. We did not attempt to forecast what actual catches would be in the future. We simply said that if F were reduced (or age at first capture increased, e.g. by a larger mesh) then catches (and catch per unit effort even more so) would be that much greater than they would have been had the reduction in F (or increase in mesh) not been made. Admittedly, this was not an easy option to sell to the industrial decision-makers, even though the resultant marginal gain (provided it was not dissipated in other ways) could have made all the difference between a weak and a strong fishing economy. But it was a start. The concept of Maximum Sustainable Yield (MSY), in absolute units, as the prime objective of fisheries management, arose I believe during the 1960's in response to a need for simple legal definition. MSY seems at first sight simple, practical and politically neutral, with catch limits as the means of control. The criticism of the economists that MSY would rarely coincide with the conditions for maximising economic rent was valid but not an overriding objection, at least for fisheries which were already overfished. In fact, by redefining the objective as actual maximum yield instead of the operational requirements (fishing rate and selectivity) for achieving a more rational exploitation, the rules of the “management game” became subtly but fundamentally altered. “Sustainable” became synonymous with “steady”, and success or failure of management became linked with the much more demanding - usually impossible - task of maintaining a constant catch rate despite often extreme natural fluctuations. The fisheries biologist, for one, was in trouble. Whether this explains the drift into the more ambitious concept of “management” instead of “regulation”, with man as the benign controller of the natural systems (and, by implication, of the socio-economic counterpart also), I do not know. If it does, then care is needed if we are to carry the confidence of the decision-makers with us in dealing with any but the simplest and most stable of fishery conditions. 353 Density-dependent complications, including stock/recruitment, may modify but do not invalidate the equilibrium or “average expectation” concepts, provided one can work on a long-term basis and accept variation in recruitment as part of the game. There are, however, some clear limitations to this approach, among them: (a) policy for fisheries in the early stage of development. Caddy (1983) gives a good analysis of these non-equilibrium situations, as do Sharp, Csirke and Garcia (this volume). (b) policy for fisheries which exist in unstable oceanographic conditions, with major periodic or episodic perturbations, as exemplified by the Peruvian anchovy and Californian and Japanese sardine. (c) policy for fisheries which are liable to collapse under heavy fishing, as exemplified by the North Sea and Atlanto-Scandian herring.