Previous Year Question
The most important fishing grounds of the world are found in the regions where
warm and cold atmospheric currents meet
rivers drain out large amounts of freshwater into the sea
warm and cold oceanic currents meet
continental shelf is undulating
Correct Answer: C
Detailed Solution
Many of the world’s highly productive fishing grounds are found in oceanic regions where warm and cold ocean currents meet. Therefore, option C is correct.
The meeting of warm and cold currents creates oceanic fronts and mixing zones. Cold water is generally richer in nutrients. The mixing of water masses and vertical movement of water help transport these nutrients into the upper, sunlit layers of the ocean.
The availability of nutrients promotes the growth of phytoplankton. Phytoplankton are the primary producers and form the base of the marine food web. They are consumed by zooplankton, which, along with other small organisms, are eaten by fish. Consequently, large populations of fish become concentrated in such regions.
Important examples include:
Grand Banks of Newfoundland: This region is influenced by the warm Gulf Stream and the cold Labrador Current.
Seas near Japan: The warm Kuroshio Current meets the cold Oyashio Current in this region.
North Atlantic fishing grounds: The interaction of warm and cold water masses creates productive marine regions.
A broad and shallow continental shelf is also favourable for fishing because sunlight can penetrate relatively deeper into shallow water. However, option D merely refers to the shelf being “undulating,” which is not the determining cause of major fishing grounds. Similarly, river mouths can be productive, but they are not the general defining feature of the world’s most important marine fishing grounds.