Key Idea: Topic 4.3 is about aquatic systems as natural capital, the limits of capture fisheries, the rise of aquaculture, and what “sustainable” aquatic food production looks like (management + regeneration).
🌊 Aquatic systems as natural capital
Renewable ≠ infinite. Overharvest can push stocks below recovery thresholds.
🎣 Capture fisheries (wild catch)
🐟 Aquaculture (fish farming) — pros & cons
Advantages: Reduces pressure on wild stocks. Reliable supply & jobs. Can be efficient protein production.
Disadvantages: Pollution (waste/chemicals). Disease spreads in crowded pens. Escapees affect wild genes/competition. Feed issue for carnivores (fish meal). Habitat loss (e.g., mangroves for shrimp).
Evaluation move: argue why herbivorous/omnivorous farmed species are usually more sustainable than carnivores.
✅ What sustainable aquatic food production looks like
1) Define MSY. 2) Two problems with capture fisheries (bycatch/trawling/IUU). 3) Two aquaculture pros + two cons. 4) Name 4 management strategies.