Q. The most important fishing grounds of the world are found in the regions where (UPSC Prelims 2013)
Answer:
warm and cold oceanic currents meet
Notes: The correct answer is
[C] warm and cold oceanic currents meet. These regions are biologically the most productive areas of the oceans, creating ideal conditions for large-scale commercial fishing.
- Mixing of Currents (Statement C is Correct): When a warm ocean current (like the Gulf Stream) meets a cold ocean current (like the Labrador Current), it causes a phenomenon called upwelling. This process brings nutrient-rich cold water from the deeper layers to the surface. These nutrients act as fertilizer for the growth of Phytoplankton (microscopic plants), which are the foundation of the marine food web.
- Ideal Temperature and Plankton: The mixing creates a temperate water environment that is neither too hot nor too cold, which is perfect for the rapid multiplication of plankton. Since fish like Cod, Herring, and Mackerel feed on plankton, these areas attract massive schools of fish.
- Atmospheric vs. Oceanic (Statement A is Incorrect): While the meeting of warm and cold atmospheric currents (air masses) creates weather patterns like fog or storms, it does not directly affect the nutrient level of the ocean water required for fish populations. However, the meeting of oceanic currents often results in dense fog, which historically made these fishing grounds dangerous to navigate.
- Freshwater Drainage (Statement B is Incorrect): While river mouths (estuaries) are productive, they do not constitute the "most important fishing grounds of the world" on a global scale compared to the open ocean current meeting points. Large amounts of freshwater can actually lower salinity, which might not be suitable for all commercial marine species.
- Undulating Shelf (Statement D is Incorrect): A wide continental shelf is generally good for fishing because shallow waters allow sunlight to reach the bottom (the photic zone), but the "undulating" (wavy) nature of the shelf is not the primary factor for high fish density.