Que. What are the forces that influence ocean currents? Describe their role in fishing industry of the world.
समुद्री धाराओं को प्रभावित करने वाली शक्तियाँ कौन-सी हैं? विश्व के मत्स्य-उद्योग में इनके योगदान का वर्णन कीजिए।
Structure of the Answer
(i) Introduction: Define “ocean currents” and mention their importance in shaping “marine ecosystems” and influencing the global “fishing industry”.
(ii) Main Body: Discuss the “forces” that influence ocean currents and describe their “role” in the global “fishing industry”.
(iii) Conclusion: Summarize the significance of ocean currents and their key role in global fishing sustainability and productivity.
Introduction
“Ocean currents” are continuous, directed movements of seawater driven by forces like “wind,” “earth’s rotation,” and “temperature variations.” They play a crucial role in shaping “marine ecosystems” and significantly impact the global “fishing industry.”
Forces Influencing Ocean Currents
Ocean currents are influenced by a combination of “atmospheric,” “gravitational,” and “thermohaline” factors that shape their movement and intensity. Key forces include:
(i) Wind Systems: Wind, particularly trade winds and westerlies, exerts “frictional force” on the water surface, generating “surface currents.” The northeast trade winds drive the “North Equatorial Current,” while the westerlies influence the “Gulf Stream.”
(ii) Coriolis Effect: Earth’s rotation causes the “Coriolis force,” which deflects ocean currents to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, creating the swirling motion of major ocean gyres.
(iii) Thermohaline Circulation: Variations in “temperature” and “salinity” cause density differences in ocean water, driving deep currents. This process, called “thermohaline circulation,” is essential for the global movement of cold and warm water masses.
(iv) Gravitational Forces: The gravitational pull of the “moon” and “sun” generates tides, which contribute to tidal currents. These currents, though localized, can influence “coastal waters” and impact fish migration and nutrient distribution.
(v) Ocean Basin Topography: The shape and structure of the “ocean floor” (ridges, trenches, continental shelves) affect the direction and speed of ocean currents, modifying their interaction with marine ecosystems and fisheries.
Role of Ocean Currents in the Fishing Industry
The “fishing industry” is significantly shaped by ocean currents, which influence the availability, abundance, and distribution of marine species. The primary roles of ocean currents include:
(i) Nutrient Upwelling: Ocean currents cause “upwelling,” where deep, cold, nutrient-rich water rises to the surface. These areas, such as along the “Peru Current” and “California Current,” become highly productive fishing zones, rich in plankton and supporting fish populations like anchovy and sardines.
(ii) Temperature Regulation: Cold and warm “ocean currents” regulate sea surface temperatures, creating favorable conditions for fish breeding. For instance, the “Benguela Current” cools the waters off Namibia, supporting large sardine populations.
(iii) Fish Migration Paths: Ocean currents guide “fish migrations” over large distances. The “Gulf Stream” and “Kuroshio Current” influence migratory routes for species like tuna, which are central to large-scale commercial fisheries.
(iv) Support for Marine Food Chains: Ocean currents facilitate the movement of plankton and nutrients, supporting entire “marine food chains.” Phytoplankton, a key food source for small fish, thrives in nutrient-rich upwelling zones, enhancing fish populations.
(v) Formation of Major Fishing Grounds: Major fishing grounds, such as the “Grand Banks” and “North Sea,” are formed by the convergence of cold and warm currents. These areas, rich in biodiversity, support major global fishing industries.
Regional Impact of Ocean Currents on Global Fisheries
Different regions of the world experience the benefits of ocean currents in various ways, contributing to regional and global fishing industries:
(i) Peruvian Fisheries: The “Humboldt Current,” a cold upwelling current along the coast of Peru, is one of the most productive marine ecosystems. It sustains a massive anchovy fishery, accounting for much of the global fishmeal production.
(ii) Japanese Fisheries: The meeting of the warm “Kuroshio Current” and cold “Oyashio Current” near Japan creates fertile fishing grounds, supporting Japan’s extensive tuna, sardine, and mackerel fisheries.
(iii) Northwest Atlantic Fisheries: The interaction of the cold “Labrador Current” and warm “Gulf Stream” off the coast of Newfoundland creates the rich fishing grounds of the “Grand Banks,” known for cod, herring, and haddock fisheries.
(iv) West African Fisheries: The cold “Canary Current” brings nutrients from deep ocean waters to the surface off the coast of West Africa, supporting fisheries in Morocco and Mauritania, rich in sardines and other pelagic species.
(v) Norwegian Fisheries: The “Norwegian Current” brings warm Atlantic waters northwards, influencing the cold Arctic waters. This creates ideal conditions for cod and herring fisheries, which are crucial to Norway’s economy.
Influence of Climate Change on Ocean Currents and Fisheries
Climate change is altering “ocean currents” in ways that can significantly impact global fisheries:
(i) Disruption of Upwelling: Warming ocean temperatures can disrupt “upwelling” processes, reducing the nutrient supply that sustains fish populations. This poses a risk to fisheries dependent on cold, nutrient-rich waters.
(ii) Altered Migration Patterns: As ocean temperatures change, fish migration patterns shift, moving species away from traditional fishing grounds. This has already affected the “North Atlantic” fisheries, with species like mackerel shifting northward.
(iii) Impact on Coastal Ecosystems: Rising sea levels and changes in coastal currents affect coastal ecosystems, including mangroves and coral reefs, which are essential breeding grounds for many fish species.
(iv) Increased Ocean Acidification: Higher “CO2 levels” lead to ocean acidification, which can weaken the shells of marine organisms like plankton, disrupting the food chain and impacting fish populations that rely on them.
(v) Policy and Management Challenges: With shifting ocean currents and changing ecosystems, sustainable fishing practices and international cooperation are increasingly critical to ensuring the long-term viability of the global fishing industry.
Conclusion
Ocean currents are fundamental to the “fishing industry,” influencing marine life, fish distribution, and fishing productivity. Understanding their role is crucial for developing sustainable fisheries and addressing climate-related challenges.
