Fish+farming

Fish Farming is the principal form of [|aquaculture], which is the farming of freshwater and saltwater organisms including [|fish] , [|molluscs] , [|crustaceans] and aquatic plants. Unlike [|fishing], aquaculture, also known as aquafarming , implies the cultivation of aquatic populations under controlled conditions. This farming provides half of the total fish and shellfish we eat. There are several different methods of aquaculture. Cage culture involves placing a mesh or wire cage in a flowing, open water system, such as a lake, stream, reservoir or ocean. The constant water flow is critical as it renews the oxygen supply and removes waste products with little effort by the aquaculturist. The size of mesh used for the cage is critical as it must prevent the entry of predators, while holding the valuable fish stock. Four different types of cages are common: fixed, floating, submersible and submerged. Closed water aquaculture systems are more technologically advanced than the open water pond, cage or raceway structures. Closed systems are essentially huge aquariums in which the water is filtered and re-circulated.

Ponds are optimal for culturing fish. Today, the majority of freshwater aquaculture still takes place in ponds. Typically, these ponds are less than a hectare in surface area, so they are easy to manage. A pond can be natural, or it can be constructed using plastic liners. While most natural ponds are filled by runoff and rainfall, well water or surface water is often pumped into the culture pond. Pond aquaculturists use two different culturing methods. Monoculture involves raising a single species, while polyculture integrates two or more compatible fish species in the same pond.

Raceways are typically rectangular structures, with water entering one end and leaving through the other. The result is a constant flow rate, where fish are continually exposed to new water. In this type of system, it is possible to maintain a high density of fish in a small volume of water.

Open-net-cage fish farming was pioneered in Norway in the 1960s. Since then, the industry has expanded to Scotland, Ireland, Canada, the U.S., and Chile, but it is dominated by a handful of multinational corporations. Open-net-cage fish farming is a controversial practice that has raised serious environmental concerns around the world. Communities on the B.C. coast rely on a healthy marine environment to support industries such as tourism, sport fishing, and commercial fishing, all of which are affected by current commercial fish-farming practices.

Some of the environmental impacts of Salmon fish farming include: sea lice, disease, algae blooms, pollution, escapes and alien species, and because farmed fish are fed pellets made from other fish, the net loss of other fish species on a global scale.