Brainlag PlusFish farming and non-indigenous species (Edexcel), the carbon cycle in numbers, the water cycle in depth, and what speeds up or slows down decomposition (Biology only).
Fish farming (Edexcel)
Fish farms keep large numbers of fish in cages or tanks and feed them a high-protein diet; limiting their movement and keeping the water at a good temperature means less energy is used in respiration, so they grow fast.
Farming gives a lot of protein-rich food and can take pressure off wild stocks.
But it has costs for biodiversity: diseases and parasites such as sea lice spread among the crowded fish and pass to wild fish; uneaten food and faeces cause eutrophication; escaped fish compete and breed with wild fish; and fishmeal for the feed is often made from wild fish.
- 2400 kg of feed; the salmon gained 1600 kg
- 1600 ÷ 2400 × 100 = 66.67% of the feed became fish
- 25% of the feed is fishmeal: 25 ÷ 100 × 2400 = 600 kg
- each kg of fishmeal needs 3 kg of wild fish: 600 × 3 = 1800 kg
The rest of this lesson and its 12 practice questions are in Plus.
Screen 1 of 5, free to read.
- 12 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards