Abstract Eastern Baltic cod is an example of a fish stock where fishing pressure has substantially declined after decades of intensive exploitation. However, in contrast to the expected improvements in stock status, stock productivity has concurrently declined to a historic low level. Targeted fisheries for the eastern Baltic cod were recently banned. However, at present low growth and high natural mortality, the stock biomass is projected to remain low, even in the absence of fishing. Thus, the future development in this stock and its potential recovery are largely dependent on ecosystem drivers likely contributing to the presently poor state of the cod stock (e.g. oxygen conditions, spatial distribution of prey species, abundance of marine mammals). Some of these ecosystem drivers and associated impacts on cod may be possible to influence by management measures, which are however not straightforward to implement. Moreover, scientific knowledge to guide management decisions in a complex ecosystem context is lagging behind. The Baltic cod case exemplifies the complexity of questions emerging for management as well as scientific advice under rapidly changing ecosystem conditions, where traditional fisheries management alone may have a limited potential to rebuild the stock.

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生态系统变化下资源管理的新挑战：波罗的海鳕鱼的例子

摘要 波罗的海东部鳕鱼是鱼类种群的一个例子，在经过数十年的集约开发后，其捕捞压力已大幅下降。然而，与库存状况的预期改善相反，库存生产率同时下降至历史低位。最近禁止有针对性地捕捞波罗的海东部鳕鱼。然而，目前低增长和高自然死亡率，即使没有捕鱼，预计种群生物量仍将保持低水平。因此，该种群的未来发展及其潜在恢复在很大程度上取决于可能导致目前鳕鱼种群状况不佳的生态系统驱动因素（例如氧气条件、猎物物种的空间分布、海洋哺乳动物的丰度）。其中一些生态系统驱动因素和对鳕鱼的相关影响可能会受到管理措施的影响，但实施起来并不简单。此外，在复杂的生态系统环境中指导管理决策的科学知识也滞后。波罗的海鳕鱼案例说明了在快速变化的生态系统条件下出现的管理问题和科学建议的复杂性，在这种情况下，仅靠传统渔业管理重建种群的潜力可能有限。