Capture fisheries
Big idea: Capture fisheries involve catching wild fish from oceans and freshwater. They have fed humanity for millennia, but many stocks are now overfished and at risk of collapse.
The overfishing problem
- ~35% of global fish stocks are overfished (FAO)
- Modern technology makes fishing too efficient (sonar, GPS, huge nets)
- Bycatch kills millions of non-target species
- Bottom trawling destroys seafloor habitats
- Illegal, unreported, and unregulated (IUU) fishing evades quotas
Impacts of overfishing
- Stock collapse — populations fall below recovery point
- Ecosystem disruption — removes key species from food webs
- Economic loss — fishing communities lose livelihoods
- Food insecurity — 3 billion people depend on fish for protein
- Trophic cascades — removing predators affects entire ecosystem
In extended answers about sustainable aquatic food production, link renewable natural capital to management. Include several distinct strategies (MSY, quotas, protected areas, closed seasons, gear restrictions, reducing bycatch) and briefly explain how each protects fish stocks and ecosystems.
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IB-style question — managing a wild fishery sustainably [4]
A coastal community's wild sardine stock is shrinking from overfishing.
Identify four strategies that could be used to manage this fishery more sustainably. [4]
How to answer it, step by step
- Limit how much is taken
• Set catch quotas at or below the maximum sustainable yield
• Use seasonal bans so fish can breed undisturbed - Protect young fish and habitats
• Set a minimum mesh size so immature fish escape the net
• Create a marine protected area (no-fishing zone) for stocks to recover
Final answer
Give four distinct strategies (one mark each) — don't list four versions of the same idea; mix supply limits with habitat/age protection.