At about 40°N and S latitudes on the western margins of the continents, the cold and warm ocean currents diverge. On the contrary, at the same latitude, along the eastern coast of the continents the cold currents flowing from the polar seas and the warm currents from the low latitudes converge.
Because of convergence, there is strong mixing of ocean waters. In such areas the nutrients so essential for marine organisms are in abundance. So the marine life is rich in such areas.
As we are aware, the most important fishing grounds in the world are located in shallow water close to the land where there is mixing of cold and warm currents from different regions. Several such examples may be given.
The major fishing grounds on earth comprise the seas north of Japan where the warm Kuroshio Current meets the cold Kamchatka Current; the Grand Banks off Newfoundland where the North Atlantic Drift encounters the cold Labrador Current; and the sea around Iceland where the North Atlantic Drift meets the East Greenland Current.
ADVERTISEMENTS:
All these areas are located in the Northern Hemisphere in areas of shallow waters. There the chemical nutrients on the floor of the sea can be mixed upward so that they are readily available to fish in surface waters where there is sufficient light and adequate quantity of oxygen.
Even though in the southern hemisphere also the cold and warm currents meet at high latitudes, there are no such fishing grounds rich in marine life. This is because of the fact that in those latitudes there is dearth of land and consequently of shallow waters full of land-derived nutrients.