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examBoard: Cambridge
examType: IGCSE
lessonTitle: Case Study: Marine Fishery Resource Management
Our oceans cover more than 70% of Earth's surface and provide food for billions of people worldwide. Marine fisheries are a vital resource, but they face serious threats from overexploitation. Understanding how to manage these resources sustainably is crucial for our future food security and ocean health.
Key Definitions:
Marine fisheries provide about 17% of all animal protein consumed globally. Over 3 billion people rely on fish as their primary source of protein. The fishing industry employs approximately 60 million people worldwide and is worth over £100 billion annually.
According to the UN Food and Agriculture Organization (FAO), about 34% of global fish stocks are being fished at unsustainable levels. Another 60% are fished at maximum capacity, leaving only 6% underfished. Without proper management, many important fisheries could collapse within decades.
Several human activities threaten the sustainability of marine fisheries. Understanding these threats is the first step toward effective management.
Catching fish faster than they can reproduce leads to population collapse. The Atlantic cod fishery off Newfoundland collapsed in the 1990s due to overfishing, causing 40,000 job losses.
Bottom trawling drags heavy nets across the seafloor, destroying habitats. Dynamite fishing and cyanide fishing in coral reefs kill non-target species and damage ecosystems.
For every 1kg of shrimp caught by trawling, up to 9kg of other marine life is caught and discarded. Globally, about 40% of marine catch is bycatch.
Fishing isn't the only threat to marine fisheries. Environmental factors also play a significant role in their decline.
Rising ocean temperatures cause fish to migrate to cooler waters, disrupting traditional fishing grounds. Ocean acidification weakens the shells of crustaceans and damages coral reefs that serve as fish nurseries. Changing ocean currents affect nutrient distribution and fish breeding patterns.
Plastic pollution entangles marine life and is ingested by fish, entering the food chain. Chemical runoff from agriculture creates "dead zones" where fish cannot survive due to low oxygen levels. Oil spills devastate marine ecosystems for decades.
Effective management of marine fisheries requires a combination of scientific, economic and social approaches.
Total Allowable Catch (TAC) limits are set based on scientific assessments of fish populations. Individual Transferable Quotas (ITQs) give fishers ownership of a percentage of the TAC, which they can trade. This creates economic incentives for sustainability.
Areas where fishing is restricted or prohibited allow fish populations to recover. These "no-take zones" can increase fish size, abundance and biodiversity. Fish that grow larger in protected areas produce more eggs, helping to replenish surrounding waters.
Mesh size regulations ensure young fish can escape nets. Bycatch reduction devices like Turtle Excluder Devices (TEDs) allow non-target species to escape. Seasonal and area closures protect spawning grounds during breeding seasons.
The Marine Stewardship Council (MSC) certifies sustainable fisheries, allowing consumers to make informed choices. Certified fisheries must maintain sustainable fish stocks, minimize environmental impact and have effective management systems.
The North Sea cod fishery nearly collapsed in the early 2000s, with stocks falling to 36,000 tonnes (compared to 270,000 tonnes in the 1970s). In response, the EU implemented:
By 2017, North Sea cod had recovered enough to receive MSC certification, though recent climate change impacts have caused some setbacks. This case demonstrates that with proper management, even severely depleted fisheries can recover.
Fish don't respect national boundaries, so international cooperation is essential for effective management.
Several international frameworks guide marine fishery management:
Modern technology is revolutionising how we monitor and manage fisheries.
Vessel Monitoring Systems (VMS) track fishing boat movements via satellite. Electronic logbooks provide real-time catch data. Onboard cameras monitor fishing activities to ensure compliance with regulations. Drones and satellite imagery detect illegal fishing in remote areas.
Acoustic surveys use sound waves to estimate fish populations without catching them. Genetic techniques help identify fish stocks and their boundaries. Computer models predict how fish populations will respond to different management strategies. Environmental DNA (eDNA) sampling detects fish presence from water samples.
The Alaska pollock fishery is one of the world's largest and most sustainable. Management includes:
Result: A stable, profitable fishery that has maintained healthy stock levels for decades.
Mediterranean bluefin tuna stocks declined by 85% between 1970 and 2007 due to:
Since 2010, stricter quotas and enforcement have helped stocks begin to recover, showing that even severely depleted fisheries can bounce back with proper management.
Effective fishery management must adapt to changing conditions and new challenges:
By implementing these approaches and learning from both successes and failures, we can ensure that marine fisheries continue to provide food and livelihoods for generations to come.
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