What threats face the oceans, and how can they be managed sustainably?
Threats to the oceans from overfishing, pollution and climate change; and the strategies and agreements used to manage and protect the marine environment.
An Eduqas A-Level Geography answer to threats to the oceans and their management in Component 2, covering overfishing and by-catch, plastic and chemical pollution, climate-related threats (warming, acidification, sea-level rise, coral bleaching), and management strategies including marine protected areas, fisheries quotas and international agreements, with examples.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
Eduqas wants you to explain the main threats to the oceans from overfishing, pollution and climate change, and evaluate the strategies and agreements used to manage and protect the marine environment.
The answer
Threats to the oceans
The oceans are degraded by three overlapping pressures. Overfishing has driven many stocks below sustainable levels, with industrial fleets, improved technology and destructive methods (bottom trawling) and by-catch compounding the damage. Pollution takes several forms: an estimated 8 million tonnes of plastic enter the oceans each year, accumulating as microplastics and in great ocean gyres; oil spills cause acute local damage; and chemical and nutrient run-off (fertilisers, sewage) causes eutrophication and oxygen-starved dead zones. Climate change adds warming (stressing species and shifting ranges), ocean acidification (from absorbed carbon dioxide, harming corals and shellfish), sea-level rise and coral bleaching, linking the oceans directly to the carbon cycle.
Management strategies
Management operates at every scale. Marine protected areas can let depleted ecosystems recover and rebuild fish stocks, especially when fully enforced "no-take" zones. Fisheries quotas and regional bodies try to keep catches within sustainable limits. MARPOL and other conventions regulate pollution from ships, and national bans target single-use plastics. The High Seas Treaty (the BBNJ agreement) aims to enable protected areas beyond national waters. The recurring weakness is enforcement: a protected area or quota only works if it is monitored and complied with, which is hard on the open ocean and against illegal, unreported fishing.
Evaluating effectiveness
Ocean management is partially effective. Where it is well-funded, enforced and cooperative, it works: well-managed MPAs restore biodiversity and recover stocks, and quotas have rebuilt some fisheries. But effectiveness is limited by the tragedy of the commons on the high seas, by weak enforcement (many MPAs are "paper parks" with little monitoring, and illegal fishing undermines quotas), and by the global scale of plastic pollution and climate change, which no local measure can solve alone. Eduqas expects a judgement that the most effective protection combines local enforcement with binding international cooperation, and that the hardest threats (acidification, plastic, the open ocean) demand global action that current governance struggles to deliver.
Examples in context
Example 1. The Great Pacific Garbage Patch and plastic pollution. The Great Pacific Garbage Patch, a vast accumulation of floating plastic and microplastics in a North Pacific gyre, is the iconic case of ocean pollution as a commons problem. Plastic enters from many countries and concentrates in international waters owned by no one, harming marine life through entanglement and ingestion and entering food chains as microplastics. Cleanup efforts and national plastic bans help at the margins, but the scale and diffuse, transboundary source mean only coordinated global action on plastic production and waste can address it, a clear Eduqas example of why some ocean threats defy local management.
Example 2. Marine protected areas and fisheries recovery. Large, well-enforced marine protected areas, such as no-take reserves that have allowed reef fish and shellfish populations to rebuild, show management working when properly resourced: biomass inside the reserve recovers and spills over to support surrounding fisheries. The contrast with weakly enforced "paper parks", where illegal fishing continues and stocks keep falling, is the standard Eduqas evaluation: MPAs are among the most effective tools available, but only where enforcement, funding and community support make the protection real rather than nominal.
Try this
Q1. Define the term by-catch. [2 marks]
- Cue. The unintended capture of non-target species (such as dolphins, turtles, seabirds or juvenile fish) during fishing, adding to the ecological damage of overfishing.
Q2. Explain why marine protected areas are not always effective. [3 marks]
- Cue. Many are weakly enforced "paper parks" with little monitoring, so illegal fishing continues and biodiversity keeps declining; effectiveness depends on proper funding, enforcement and community support, not just designation.
Exam-style practice questions
Practice questions written in the style of WJEC Eduqas exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Eduqas 2019 (style)6 marksExplain the main threats to the world's oceans.Show worked answer →
Group the threats and explain the cause and effect of each.
Overfishing: catches exceeding stock reproduction, plus by-catch and destructive methods, collapse fish stocks and damage ecosystems.
Pollution: plastic waste (microplastics, gyres), oil spills, chemical run-off and nutrient pollution causing eutrophication and dead zones.
Climate change: warming, ocean acidification (from absorbed carbon dioxide), sea-level rise and coral bleaching degrade marine ecosystems.
A strong answer links each threat to its impact on biodiversity, food supply and the ocean's role in the climate system.
Markers reward grouped threats with cause and effect and named examples.
Eduqas 2022 (style)12 marksEvaluate the effectiveness of strategies used to manage and protect the oceans.Show worked answer →
A 12-mark evaluation needing a judgement about effectiveness.
Outline strategies: marine protected areas (MPAs) and reserves; fisheries quotas, catch limits and regional fisheries management; bans on destructive practices; pollution controls (MARPOL, plastic reduction); and international agreements (UNCLOS, the High Seas Treaty).
Evaluate effectiveness: MPAs can restore biodiversity where well enforced but many are paper parks with weak monitoring; quotas work where states comply but are undermined by illegal fishing and the high-seas commons; pollution treaties reduce ship pollution but struggle with diffuse plastic; agreements set frameworks but lack enforcement.
Conclude that management is partially effective: it succeeds where it is well-funded, enforced and cooperative (a well-managed MPA), but the commons problem, weak enforcement and the global scale of pollution and climate change limit it, so the most effective protection combines local enforcement with binding international cooperation.
Markers reward a balanced, exemplified judgement against criteria.
Related dot points
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An Eduqas A-Level Geography answer to the synoptic 21st Century Challenges in Component 2 Section C, covering how to draw together physical and human geography across scales, the great contemporary challenges (climate change, resource security, migration, inequality, urbanisation), the use of a stimulus resource, and how to evaluate strategies and futures synoptically.
- The role of the carbon cycle in the greenhouse effect and the Earth's energy balance; positive and negative feedbacks; and strategies to mitigate climate change.
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Sources & how we know this
- Eduqas A-level Geography specification (from 2016) — Eduqas (2016)