What are the forces that influence ocean currents? Describe their role in fishing Industry of the world.

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Ghissu Editorial · Accepted Answer

Ocean currents are driven by planetary winds, the Coriolis force, density differences from temperature and salinity, and gravity and coastline shape, and they create rich fisheries where warm and cold waters meet or cold water upwells. The Gulf Stream and Labrador current together make the Grand Banks fishing ground.

**Introduction**

Ocean currents are steady movements of seawater driven by winds, the Earth's rotation and density differences. By deciding where nutrient-rich cold water meets sunlight, they decide where the richest fishing grounds lie.

**Forces That Influence Ocean Currents**

1. **Planetary winds**: Trade winds and westerlies drag surface water, and the monsoon reverses north Indian Ocean currents twice a year.
2. **Coriolis force**: Rotation deflects currents right in the Northern Hemisphere and left in the Southern, forming gyres.
3. **Density differences**: Temperature and salinity drive the thermohaline circulation, such as the saline Mediterranean outflow at Gibraltar.
4. **Gravity and coastlines**: Landmasses steer flows, as Cape Sao Roque splits the South Equatorial Current.

**Role of Currents in the World's Fishing Industry**

FIGURE: geography-p9-1 | World ocean currents: warm and cold flows, with convergence and upwelling zones

1. **Warm and cold convergence**: The Gulf Stream and Labrador current create the Grand Banks, and the Kuroshio and Oyashio enrich the grounds off Japan.
2. **Upwelling zones**: Cold currents on western margins lift nutrients, sustaining Peru's anchoveta fishery of the Humboldt current and the Benguela fishery off Namibia.
3. **Ice-free coasts**: The North Atlantic Drift keeps Norway's coast open for year-round fishing.
4. **Weak tropical fisheries**: Warm tropical waters yield less, though monsoon upwelling off Kerala supports the oil sardine, and El Nino collapsed Peru's anchoveta catch in 1972-73.

**Way Forward**

1. **Advisories and quotas**: INCOIS Potential Fishing Zone advisories and science-based catch limits, the lesson of Canada's 1992 cod moratorium, should go together.

**Conclusion**

Winds, rotation, density and coastlines move the oceans and decide where fish gather, so a fishing industry that reads currents scientifically and fishes within limits can stay productive.

What are the forces that influence ocean currents? Describe their role in fishing Industry of the world.

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