鱼类洄游（fish migration），指鱼类因生理要求、遗传和外界环境因素等影响，引起周期性的定向往返移动。洄游是鱼类在系统发生过程中形成的一种特征，是鱼类对环境的一种长期适应，它能使种群获得更有利的生存条件，更好地繁衍后代。研究并掌握鱼类洄游规律，对于探测渔业资源量及其群体组成的变化状况，预报汛期、渔场，制订鱼类繁殖保护条例，提高渔业生产和资源保护管理的效果及放流增殖等具有重要意义。其他水生动物如对虾等也有洄游习性。
但是，由于作为研究对象的鱼类洄游于上述两个海域之间，于是问题也就产生了：捕鱼活动在部分海域的减少，对鱼类数目的影响究竟有多大。
The fish species in question, however, migrate between these two areas, so the question was how much the reduction of fishing effort in part of their range would affect their Numbers.
这些鱼类分为4个主要生态类型，包括河口性鱼类、近海鱼类、江海洄游型鱼类和淡水鱼类。
These fish could be categorized into four types, including estuarine fishes, marine fishes, diadromous fishes and of freshwater fishes.
但有一点是显而易见的：停止捕鱼活动（即便只持续六年时间）对于洄游鱼类的影响，与对于非洄游鱼类的影响同样大。
But one lesson is clear. Laying off, even for just six years, has as big an effect on migratory fish as it does on sedentary ones.
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