Fish farming in the UK
Many species of fish are used in aquaculture, and they're farmed in both freshwater and seawater. They're produced in a variety of systems, ranging from closed systems, where the water is artificially re-circulated, to open systems where the fish are contained in more natural bodies of water, such as a pond or sea enclosure. Here's more on how fish farming works in the UK.
Farming of Atlantic salmon
Atlantic salmon is one of the most commonly farmed fish species in the UK, with farms mainly located in the Scottish highlands. There are freshwater and seawater stages to their lives.
Fertilised salmon eggs are usually grown in trays. The eggs hatch into 'alevins' or 'yolk sac fry' and spend time on the bottom of their trays until their yolk sac has been absorbed. They then start to rise up into the water column as 'first feeding fry'.
As 'first feeding fry', they're transferred to larger tanks or freshwater lochs. They spend a significant period of time in freshwater before they're ready to go to sea.
Eventually, certain physiological and external signals trigger a transformation in the appearance and behaviour of the young salmon. These changes result in the young fish being ready to go to sea - a process called 'smoltification'. The fish will then be reared in seawater enclosures for the next one to two years.
End of production
Once salmon have reached the required weight, they're pumped or netted out of their enclosure and slaughtered.
There are a number of ways fish can be transported, the most common being by road, boat or helicopter. One method is wellboats, where the fish are transported in a specially-designed well in the hold of the boat. The water quality (temperature, pH, oxygen etc.) in the wellboats can be controlled, and underwater cameras monitor the fish.
Find out about some of the key welfare issues for farmed fish.