Szuwalski Cody S, Burgess Matthew G, Costello Christopher, Gaines Steven D
Sustainable Fisheries Group, University of California, Santa Barbara, CA 93106;
Bren School of Environmental Science and Management, University of California, Santa Barbara, CA 93106.
Proc Natl Acad Sci U S A. 2017 Jan 24;114(4):717-721. doi: 10.1073/pnas.1612722114. Epub 2016 Dec 27.
Indiscriminate and intense fishing has occurred in many marine ecosystems around the world. Although this practice may have negative effects on biodiversity and populations of individual species, it may also increase total fishery productivity by removing predatory fish. We examine the potential for this phenomenon to explain the high reported wild catches in the East China Sea-one of the most productive ecosystems in the world that has also had its catch reporting accuracy and fishery management questioned. We show that reported catches can be approximated using an ecosystem model that allows for trophic cascades (i.e., the depletion of predators and consequent increases in production of their prey). This would be the world's largest known example of marine ecosystem "engineering" and suggests that trade-offs between conservation and food production exist. We project that fishing practices could be modified to increase total catches, revenue, and biomass in the East China Sea, but single-species management would decrease both catches and revenue by reversing the trophic cascades. Our results suggest that implementing single-species management in currently lightly managed and highly exploited multispecies fisheries (which account for a large fraction of global fish catch) may result in decreases in global catch. Efforts to reform management in these fisheries will need to consider system wide impacts of changes in management, rather than focusing only on individual species.
在世界许多海洋生态系统中，都存在着不加区分的高强度捕捞现象。尽管这种做法可能会对生物多样性和单个物种的数量产生负面影响，但它也可能通过移除掠食性鱼类来提高渔业总产量。我们研究了这种现象能否解释东海地区上报的高野生捕捞量，东海是世界上生产力最高的生态系统之一，但其捕捞量报告的准确性和渔业管理也受到了质疑。我们表明，可以使用一个考虑营养级联效应（即掠食者数量减少及其猎物产量相应增加）的生态系统模型来估算上报的捕捞量。这将是世界上已知的最大的海洋生态系统“工程”实例，并表明在保护与粮食生产之间存在权衡。我们预测，通过改变捕捞方式，可以提高东海的总捕捞量、收入和生物量，但单物种管理会通过逆转营养级联效应而降低捕捞量和收入。我们的结果表明，在目前管理宽松且过度开发的多物种渔业（占全球鱼类捕捞量的很大一部分）中实施单物种管理，可能会导致全球捕捞量下降。对这些渔业进行管理改革的努力需要考虑管理变化对整个系统的影响，而不是只关注单个物种。
