迴游的描述鱼类迁徙的习惯，例如溯河洄游产卵或降海洄游。
中华人民共和国对源自本国河流的溯河产卵种群，享有主要利益。
溯河型（称作“刚头”）迁徙到海中生活，尽管它们需要回到淡水中产卵。
大多数迁移鱼类（如鲑鱼和鲱鱼）是溯河产卵种群。它们在淡水产卵，成年后生活在咸水中。
1·Any of various primitive elongated freshwater or anadromous fishes of the family Petromyzontidae, characteristically having a jawless sucking mouth with rasping teeth.
七鳃鳗，八目鳗一种七鳃鳗科的原始细长淡水或溯河产卵鱼，特点是长有无。
1·Any of various freshwater or anadromous food and game fishes of the family Salmonidae, especially of the genera Salmo and Salvelinus, usually having a streamlined, speckled.
鳟鲑鱼科的各种淡水或溯河性食用及捕钓鱼，尤指鲑鱼属和红点鲑属，通常。