Key Idea: Most marks in topic 4.3 come from aquaculture and managing fisheries. Learn those first, then overfishing and maximum sustainable yield.
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
- Bottom trawling, ghost nets, poisons and explosives destroy habitats.
- The Grand Banks cod collapsed in 1992 and has not recovered.
- MSY is the largest catch that can be taken each year without shrinking the stock.
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 |
Last-minute check: answer, then tap to see.
Name two impacts of shrimp farming. Mangrove loss and pollution from feed and waste.
How does a bigger mesh size help? Young fish escape and can breed.
What happened to the Grand Banks cod? The fishery collapsed in 1992.
What does MSY stand for? Maximum sustainable yield.
IB-style questionExplain[4 marks]
Atlantic salmon are farmed in open net pens in Norway's fjords. Explain the environmental impacts of this salmon farming.
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.
- Use the Grand Banks cod as your named collapse.