Intensive Farming - Fish Farming
Biology: Edexcel IGCSE, topic 6.1.4
Fish Farming
Fish is an important source of protein for many people. Fish can be farmed in large numbers to increase yield. Fish farms can be areas enclosed by nets out in the open sea, or open tanks on land. Fish farming reduces fishing pressure on wild fish populations, but affects the environment in other ways.
Water Quality
- Fish farms in open seas receive fresh seawater with the movement of the tide, but water quality in fully enclosed fish farms must be tested regularly.
- It is important that oxygen levels in the water are high, and the nitrogenous waste produced by fish is removed.
Predation
- Interspecific predation involves other species preying on farmed fish.
- Nets keep out most aquatic predators from off-shore farms, and seabirds are kept out by netting across the top of farms.
- Intraspecific predation involves the farmed fish eating each other.
- This can be prevented by feeding the fish the right amount, and by not keeping them in conditions that are too cramped.
Feeding
- Fish are fed to maximise growth, size and total yield, whilst minimising cost and waste.
- Feed is often high in protein to maximise growth.
Disease
- Fish parasites (such as sea lice) and diseases can easily spread through fish farms, because large numbers of fish are kept in very close proximity.
- Often antibiotics are added to feed.