Fish farming started thousands of years ago in China and back then the fish were raised in ponds. Eventually fish farming spread to Europe where the fish were not only raised in farms but they were also raised in land-based tank systems. The traditional methods proved to be sustainable because it was ecologically friendly, increased the amount of food, and reduced energy costs in searching for, gathering, and transporting food. The open-netcage fish farming was pioneered in the 1980’s by Norway. Salmon farming began during the 1970’s. The open-netcage isn’t ecologically friendly. They have a high density of salmon, allowing diseases and parasites to amplify, then go out and spread to marine life. The excess feed and feces smother the ocean floor setting up anoxic conditions. When a disease breaks out in a salmon farm, the salmon are fed their regular pellets with antibiotics in them. Most of the antibiotics are excreted onto the bottom or in the ocean. Netcages mainly have copper-based paint, which makes its way into the marine waters; there are also other metals present in the paint. If the metals don’t cause death, they still have sub-lethal effects. They can inhibit chemoreceptors of marine animals, therefore affecting food ingestion, also their nervous system. Pesticides are also used and they disrupt neurological processes, by binding to biological membranes. Farmed fish are stressed, which suppresses their immune system. That makes them more vulnerable to diseases, therefore when salmon escape, they spread diseases and parasites quicker than non farmed salmon.
That's my proofread version. Not much changed really...mostly in the first bit.
