Model uncertainty in the ecosystem approach to fisheries

Fisheries scientists habitually consider uncertainty in parameter values, but often neglect uncertainty about model structure, an issue of increasing importance as ecosystem models are devised to support the move to an ecosystem approach to fisheries (EAF). This paper sets out pragmatic approaches with which to account for uncertainties in model structure and we review current ways of dealing with this issue in fisheries and other disciplines. All involve considering a set of alternative models representing different structural assumptions, but differ in how those models are used. The models can be asked to identify bounds on possible outcomes, find management actions that will perform adequately irrespective of the true model, find management actions that best achieve one or more objectives given weights assigned to each model, or formalize hypotheses for evaluation through experimentation. Data availability is likely to limit the use of approaches that involve weighting alternative models in an ecosystem setting, and the cost of experimentation is likely to limit its use. Practical implementation of an EAF should therefore be based on management approaches that acknowledge the uncertainty inherent in model predictions and are robust to it. Model results must be presented in ways that represent the risks and trade‐offs associated with alternative actions and the degree of uncertainty in predictions. This presentation should not disguise the fact that, in many cases, estimates of model uncertainty may be based on subjective criteria. The problem of model uncertainty is far from unique to fisheries, and a dialogue among fisheries modellers and modellers from other scientific communities will therefore be helpful.     

Strength in diversity: fish sanctuaries and deep-water pools in Lao PDR

Abstract  Fish sanctuaries are types of aquatic protected areas common throughout the landlocked country of Lao PDR. The key to their successful implementation in Laos appears to be local support. Therefore, they fit well within the context of community-based fisheries/co-management programmes. Fish sanctuaries are almost always established in deep-water pools, which serve as important dry season refuges for fish. The best-known fish sanctuaries in Laos are known as Fish Conservation Zones (FCZs), and are found in the mainstream Mekong River in Khong district, Champasak province, southern Laos. In Khong, there is increasing evidence that FCZs established by villagers, but with government support, are important places of concentration for various fish species. FCZs can benefit fish stocks, especially relatively sedentary species, but also highly migratory ones. FCZs are not panaceas for solving all the fisheries problems in Laos or the Mekong River Basin, but they represent important management tools that should not be overlooked.     

广东省海洋捕捞产量灰色预测

为摸清今后海洋捕捞业的发展动态,以广东省海洋与渔业局提供的1996～2003年广东省海洋捕捞业统计数据为基础,分别建立灰色预测模型,通过模型对广东省海洋捕捞业发展趋势做出了近5年预测。预测结果,2010年海洋捕捞产量在167×104t,南海的捕捞产量为156.78×104t,远洋渔业产量为19.82×104t。通过对预测结果的可信度进行分析,进一步确定这种分析结果的合理性,从而为确定今后广东省海洋捕捞业发展方向,渔业生产部门制订投资决策和合理安排生产提供科学依据。     

辽宁开展节水型渔业存在的问题及其对策

文章以辽宁水资源和渔业生产的现状为研究背景,以介绍节水型渔业的概念、意义等为基础,分析了辽宁开展节水型渔业存在的认识问题、投入问题、体制问题,提出了辽宁开展节水型渔业的四项基本对策,即在建设节约型社会,发展节约型经济的框架下开展节水型渔业;完善政策法规,制定节水型渔业建设规划;转变渔业增长方式,推行节水技术;限制和制止浪费水严重、污染严重的渔业项目。