How has over-fishing affected the seas?

                   Modern fishing methods are capable of sweeping up almost all the fish in a particular area. In addition, these methods destroy those fish that are not caught by damaging their habitat.

                  This damage has become apparent when trawlers stir up the sea-bed as they tow along huge nets. The nets destroy young fish and the shellfish on which the adults normally feed. When too many fish are caught, the young may never grow big enough to breed, and the fish population will suddenly become much depleted. This happened in recent years when herring and cod were overfished in the Atlantic Ocean.

                  Large fish such as tuna and sharks have been almost wiped out in some regions because of over-fishing. The main culprit has been giant gill-nets, sometimes many kilometres in length. These can catch literally all of the fish in a large area, and at the same time, cause the death of air- breathing dolphins by drowning them.

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