Whereas rights-based catch regulations such as individual transferable quotas (ITQs) are gaining traction as the key management instrument in many fisheries, most fisheries are additionally regulated by gear restrictions, minimum landing sizes, and similar measures that intend to protect young fish from being caught. Here we study the incentives to fish selectively in a second-best setting, where the regulator issues quotas of different types and fishers choose the size of the fish they catch. We find that if quotas are specified in terms of the number of fish, rather than biomass or weight, fishers have substantial incentives to target larger fish. Thus juvenile fish are protected without need for gear restrictions. We develop the economic principles in an analytical model and quantify results for empirical examples. We find that steady-state profits under second-best deregulated number quota management are only 0.1%–2.1% below the first-best optimum.

中文翻译：

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捕鱼配额应按数字衡量吗？

尽管基于权利的捕捞法规（例如个人可转让配额（ITQ））已成为许多渔业的主要管理手段，但大多数渔业还受到渔具限制，最小着陆面积以及旨在保护幼鱼免遭破坏的类似措施的监管。抓住。在这里，我们研究了在第二好的环境中选择性捕捞的诱因，在这种环境中，监管机构发布了不同类型的配额，而渔民则选择了他们捕捞的鱼的大小。我们发现，如果配额是根据鱼类的数量而不是生物量或重量指定的，则渔民有很大的动机去瞄准更大的鱼类。因此，无需限制渔具就可以保护幼鱼。我们在分析模型中开发了经济原理，并量化了经验示例的结果。