魚類一生都棲息在水裹,大多数的魚都有着紡錘狀的身體,是游行迅速的生物。魚類活動的範圍是彼此不同的有的終生静止在一個地方,如淡水里的泥鰌,深海底的燈笼魚;有的则隨季節的变化,自然環境的變化及它自身生理的原因等,進行長距離的遷移游動。它們常在一定時期成羣結隊的游行到一、二千公里以外的地區去,有的甚至長到七、八千公里(如游到大西洋中去的鳗魚),這種長距離的定期的集體的移動,稱为魚类的“洄游”。魚類洄游現象多發生在海洋魚類,淡水魚類這種情况較少。 魚羣密集活動的地方,是捕魚最好的地方,叫做漁場。明瞭魚類洄游的路線,便可以判斷各個時期漁場的地點,及推定漁場的範圍。所以魚類洄游的情形 Fish live in water all their lives. Most fish have a spindle-like body and are fast-moving creatures. The range of fish activities is different from each other, some live in a place for a lifetime, such as mud in fresh water, lantern fish in the deep sea, and others change with the seasons, changes in the natural environment and its own physiological reasons. Long distance migration swims. They often march in droves in a certain period to areas one or two thousand kilometers away, and some even grow to seven or eight thousand kilometers (such as trout swimming into the Atlantic Ocean). This long-distance regularity The collective movement is called “fishing” of fish. The phenomenon of fish migration occurs mostly in marine fish, and freshwater fish are less frequent. The place where fish is densely populated is the best place for fishing, called fishing grounds. By knowing the route of fish migration, it is possible to determine the location of fisheries at various times and to presume the scope of the fishery. So the situation of fish migration