Stock assessment for fishery management - Library

76 Stock assessment for fishery management3.6 Providing management adviceHaving estimated the levels of fishing mortality, biomass or other indicators to be usedas reference points, and the current levels of these indicators in the fishery, the next stepis to provide clear advice to the managers. The provision of such information should beseen as a regular (e.g. annual) process, that is driven by the objectives of the fishery andthat guides the management actions that will be taken in the near future. Feedback tothe advice should be provided by the managers and other interest groups to guide thefuture supply of information for the fishery (see Figure 10 of Cochrane, 2002c).In the simplest case, and where a decision control rule system is already in place, theadvice to managers may simply provide the current levels of the indicators relative tothe reference points, as required for the pre-agreed control rule management approach(see Sections 2.5.3, 3.6.1). Usually this advice will need to be supplemented withother information providing a more detailed assessment of the fishery’s prospects.As described in the following sub-sections, information may thus be provided onthe implications of alternative management strategies for each of several indicatorsrelating to the fishery objectives. Decisions taken will need to recognize the tradeoffsbetween the different objectives. Projections may also be made predicting the levels ofthe indicators in the future and the time that different management actions may taketo achieve their objectives. Advice must also be provided on the various uncertaintiesin the assessments and the risks of bad results being obtained with each alternativemanagement strategy. Although the simple control rule system is listed first below,the actual formulation of the control rules and the selection of the limits, targets andprecautionary thresholds should ideally be decided based on a full examination of thetradeoffs and uncertainties from the other analyses.Although enormous advances have been made in stock assessment methods inrecent decades, fuelled especially by easy access to powerful computing capacity, formalapproaches to decision-making in fisheries have made less progress (Cochrane, 2002c).The need for participation of stakeholders in decision making is now well recognizedbut not yet always well facilitated. Since different stakeholders will have differentobjectives for the fishery, and since managers usually set multiple competing objectives,the selection of management options can be the subject of much debate and argument.Without a clear decision-making process, the outcome can be dominated by the strongestpersonalities and prone to bias due to “self-interest, short-term objectives promptedby immediate problems, and hidden agendas” (Cochrane, 2002c). Formal statisticalmethods are available to assist with decision making but are not in common use.To reduce the chance of bad decisions being made, and to achieve the long-term goalsand objectives of the fishery, it is therefore essential that decision makers and otherstakeholders are provided with relevant, objective and easily understood informationby fisheries scientists. As described below, advice can either be provided in graphicalform or using “decision table” approaches. Managers should guide the scientists onwhich formats are most useful to them. Whatever approach is used, decision makersmust understand the importance of considering uncertainty, of weighing up competingobjectives and of taking a long-term (as well as a short-term) view.Finally, as emphasized by the precautionary approach, although managementshould be based on the “best available science” (e.g. all the advice described below), theabsence of full scientific analyses should not be used as an excuse to avoid necessarymanagement actions. Where the fishery is “data poor” and the scientific advice is lessthan complete, decision makers still have an obligation to make management decisions,aimed at achieving the goals and objectives of the fishery, and keeping precaution inmind. The provision of technical advice should be seen as a step in this managementprocess, not as an end in itself (Mahon, 1997). The flow of advice, consultation,decision-making and feedback should be clearly identified (Caddy and Mahon, 1995;Cochrane, 2002c).