Key Idea: Most marks in topic 4.3 come from aquaculture and managing fisheries. At HL, also learn assessing fish stocks, the risks of MSY, UNCLOS and hunting marine mammals.
1. Aquaculture (most marks)
- Farming fish, shellfish and seaweed, to feed more people.
- Impacts: habitat loss (mangroves cut for shrimp), waste, antibiotics, disease, escapees.
- Fixes: integrated farms with seaweed and shellfish, closed pens, eco-labels.
2. Managing fisheries
- Quotas, permits, closed seasons, bigger mesh sizes and no-take zones.
- Marine protected areas let fish breed and spill over.
- Labels such as MSC let consumers choose sustainable fish.
3. Overfishing and HL ideas
- Bottom trawling, ghost nets, poisons and explosives destroy habitats.
- The Grand Banks cod collapsed in 1992 and has not recovered.
- At HL: assessing stocks, the risks of MSY, UNCLOS and hunting marine mammals.
How it is examined:
| Question | How to score |
|---|---|
| [1] to [2] Read a catch or farming graph | Quote the trend with figures and years. |
| [2] to [4] Outline impacts of aquaculture | One impact per point, tied to the farm type. |
| [4] Outline fisheries management measures | Name the measure and how it protects stocks. |
| [7] Evaluate aquaculture or a management plan | Strengths, limitations and a judgement. |
| [9] Discuss sustainable aquatic food | Wild and farmed, named examples, both sides. |
Key terms, one line each:
| Term | In one line |
|---|---|
| Aquaculture | farming fish, shellfish or seaweed |
| Maximum sustainable yield | the largest catch that can be taken every year without depleting the stock |
| Bycatch | animals caught by accident, such as turtles in nets |
| Ghost fishing | lost nets that keep trapping animals |
| Marine protected area | a sea area where fishing is limited or banned |
| Exclusive economic zone | the sea up to 370 km from a coast, where that country controls fishing |
Last-minute check: answer, then tap to see.
Why is fishing at MSY risky? MSY is only an estimate, and stocks change year to year.
How far does an EEZ reach? 370 km from the coast.
Name one way to measure a fish stock. Acoustic surveys or catch per unit effort.
Who must cooperate for a stock to recover? Governments, fishers, consumers and NGOs.
IB-style questionExplain[4 marks]
A government sets its cod quota at the estimated maximum sustainable yield. Explain the risks of this decision.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Exam tips
- Name the type of farm or fishing method in every point.
- For a management measure, say what it protects: young fish, breeding adults or habitat.
- In an evaluate, give both sides and a judgement.
- For MSY, say it is an estimate and explain the positive feedback.