Confronting challenges to integrating Pacific salmon into ecosystem-based management policies

Ecosystem-based management is an increasingly prominent paradigm for the management of living marine resources with a focus on maintaining ecosystem level properties and processes. Although highly migratory marine and anadromous fish species often disproportionately contribute to the structure and function of ecosystems, incorporating these species into ecosystem-based management policies remains difficult because they spend a considerable portion of time outside the boundaries that define a particular management area. In this paper, two case studies are used to examine how the challenges of ecosystem openness, imperfect information, and ecosystem complexity can impede efforts to integrate highly migratory Pacific salmon into ecosystem-based management policies. This analysis highlights three main factors that hinder more effective integration: (1) uncertainties about impacts of human activities and ecological processes that occur in geographically distant jurisdictional areas or at spatial scales larger than the ecosystem-based management area, (2) spatial asymmetries in the distribution of costs and benefits associated with management decisions (i.e., positive or negative externalities), and (3) static management policies that prevent updating management decisions in a timely manner when ecosystem conditions change or new information becomes available. Given these factors, two potential strategies to address migratory challenges are suggested. First, the creation of an international ecosystem synthesis group is recommended to facilitate the collection, analysis, and dissemination of ecological, social, and policy information across national and other jurisdictional boundaries. Second, the expanded use of dynamic in-season management policies is recommended, which allow for rapid updating of management decisions based on evolving information about ecosystem conditions.     

大西洋鲑幼鱼适宜投喂频率和胃排空研究

为探究大西洋鲑(Salmo salar)幼鱼的适宜投喂频率和胃排空规律,进行了养殖实验和胃排空实验.养殖实验设置了1次/天(F1组)、2次/天(F2组)、3次/天(F3组)、4次/天(F4组)和连续投喂(C F组)共5种投喂频率.胃排空实验采用连续测定胃含物的方法,用数学模型对胃含物数据进行拟合.研究表明:F1组日摄食...