Construction of a dam on a river often results in the reduction of fish catch. Why is it so?

● Dams are been constructed on river which holds large amount of water.

● It makes water stagnant but it provides suitable living conditions for lots of aquatic organisms which habitat in dam water.

● Since fishes breed in clean and running water it cannot sustain and breed in stagnant river water in a dam.

● Therefore, as they can’t sustain in the dam their breed decrease and some eventually die.

● Hence, we can say that construction of dams on the river often results in a reduction of fish catch.