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182 biology and management. Pages 3-51 in R. Vi bert, edi1or. Fishing with electricity. Its application to biology and management. Food and Agriculture Or- pnization of the United Nations, Fishing News Boob, London. \ \ GA TZ ET AL. Whaley, R. A., O. E. Maughan, and P. H. Wiley. 1978. Lethality of electroshock to two freshwater fishes. Progressive Fish-Culturist 40:161-163. North American Jotlrnal of Fisheries Managemrllf 6: 183-191, 1986 ~. Copyright by the American Fisheries Society 1986 Risk Analysis in the Georges Bank Haddock Fishery- A Pragmatic Example of Dealing with Uncertainty B. E. BROWN! Northeast Fisheries Center, National Marine Fisheries Service Woods Hole. Massachusetts 02543, USA Department oj Statistics. Pennsylvania State University University Park, Pennsylvania 16802. USA G. P. PATlL Abstract. -Risk analysis is a rapidly developing technique and emphasis on the use of proba- bilistic models is increasing. In the field of fisheries science, stock assessment has traditionally provided future projections in a deterministic manner. However, the input parameters required for such projections are estimated with considerable uncertainty. Confidence limits and sensitivity analysis have been used to make advice more realistic. Present techniques of risk analysis may provide an alternative procedure for providing assessment advice that couches the uncertainty of projections in terms of relative risk associated with various management options. Hopefully, this form will be more useful and relevant for those making management decisions. In this paper, we describe the stock assessment advice given in 19RQ for the Georges Bank haddock stock (Melano- grammus aeglefinus), and rephrase it in risk an!.!):sis terms to illustrate the potential use of this tool. The subject of risk analysis has received increas- ing attention during the past decade. During this period, literature on risk analysis has grown from a handful of articles and books to a formidable collection of material. More than 1,000 titles were published during the 1970s on technological work dealing exclusively with the measurements of probability and uncertainty in risk situations. The Society for Risk Analysis has been established along with a journal to support the work of the Society. The American Statistical Association and the Eco- logical Society have scheduled special sections on risk analysis at their annual meetings. Risk analysis for the purpose of this paper can be defined as the evaluation of the probability of an end event or events happening which result from a combination of events. Risk analysis has i been used extensively in the evaluation of health :\hazards, effects of large-scale environmental im- pacts such as nuclear power plants, and safety con- cerns in industry. In addition, stochastic tools have been used to evaluate the profit and loss risks of business decisions. In fact, people have used some type of risk analysis since prehistoric times, both I Present address: Southeast Fisheries Center, Nation- al Marine Fisheries Service, 75 Virginia Beach Drive, Miami, Florida 33149, USA. as individuals and as societies speaking through governments, for making decisions based on eval- uations of the risks involved. More formal appli- cations in the engineering field systematize the evaluation of risk particularly when there are many elements entering into these decisions. The engi- neering assessments of risk were deterministic ini- tially and, although linking together the probabil- ities of events happening, did not consider that these probabilities were not known exactly and could vary. The recent thrust on risk analysis has been towards stochastic models, after recognition that there is a great deal of uncertainty involved in the estimates ofthe individual elements going into risk analysis. Risk analysis in the environmental area gener- ally has been directed towards the question of the adverse effects due to a stressor, i.e., something that causes stress on the system under study. The question of risk is not whether or not there is an effect but rather how great the effect will be; the goal of risk assessment is to provide the analysis and framework so that decision-makers can decide how much effect is too much. Despite the bur- geoning of activity and interest, there has been little application of the concept of risk analysis to fishery assessment situations. Compared to the physical sciences and engineering, biological and ecological variability and uncertainty are very large. 183