Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1;
School of Aquatic and Fisheries Sciences, University of Washington, Seattle, WA 98195-5020.
Proc Natl Acad Sci U S A. 2017 Nov 14;114(46):12333-12337. doi: 10.1073/pnas.1705525114. Epub 2017 Oct 26.
There is growing awareness of the need for fishery management policies that are robust to changing environmental, social, and economic pressures. Here we use conventional bioeconomic theory to demonstrate that inherent biological constraints combined with nonlinear supply-demand relationships can generate threshold effects due to harvesting. As a result, increases in overall demand due to human population growth or improvement in real income would be expected to induce critical transitions from high-yield/low-price fisheries to low-yield/high-price fisheries, generating severe strains on social and economic systems as well as compromising resource conservation goals. As a proof of concept, we show that key predictions of the critical transition hypothesis are borne out in oceanic fisheries (cod and pollock) that have experienced substantial increase in fishing pressure over the past 60 y. A hump-shaped relationship between price and historical harvest returns, well demonstrated in these empirical examples, is particularly diagnostic of fishery degradation. Fortunately, the same heuristic can also be used to identify reliable targets for fishery restoration yielding optimal bioeconomic returns while safely conserving resource abundance.
人们越来越意识到，渔业管理政策需要具有抵御不断变化的环境、社会和经济压力的能力。在这里，我们使用传统的生物经济理论来证明，由于捕捞，内在的生物限制和非线性的供求关系会产生阈值效应。因此，由于人口增长或实际收入提高而导致的总需求增加，预计将导致从高产量/低价格渔业向低产量/高价格渔业的关键转变，从而对社会和经济系统造成严重压力，并损害资源保护目标。作为概念验证，我们表明，在过去 60 年中经历了捕捞压力大幅增加的海洋渔业（鳕鱼和无须鳕）中，关键转变假说的关键预测得到了证实。在这些经验性例子中，价格与历史捕捞收益之间的驼峰形关系特别能说明渔业退化的情况。幸运的是，同样的启发式方法也可以用来确定渔业恢复的可靠目标，从而在安全保护资源丰度的同时获得最佳的生物经济回报。
