Aquaculture is huge business; salmon, oysters, shrimp, catfish, and dozens of other edible species are raised by the ton all over the world. Norway has become something of a specialist-nation when it come to raising Atlantic salmon. They say that over 14 million Norwegian salmon meals are eaten every day around the world; that requires a lot of salmon and that in turn requires an efficient method of farming. In total more than two million tons of salmon are raised around the world annually.
The young fish are hatched and raised in large indoor facilities. They are transferred to large outdoor pens to mature into 15+ pound marketable fish. In the places where you can tour the growing pens you can see the automatic feeders, underwater cameras, thermometers, and all sorts of things to insure that the water and fish are ideal. At the site we visited, the nuisance creatures (sea lice primarily) were controlled by “cleaner fish” (wrasse) rather than by chemicals. But in a sense of balance I must say that there are articles on the use of chemicals in Norwegian (and all the others as well) salmon farms. Some skeptics say there is some chemical use and others say that any country that still kills whales should be boycotted – this is a bit of apples and oranges for most people. It is broadly perceived that Norway, despite whatever it uses to protect fish from parasites and to foster growth, uses significantly fewer chemicals than does any other major producer.
The information available from various sources is not at all similar when it talks about salmon production. One source, a Norwegian poster, says that Norway produces 63% of the penned salmon and that North America and Chile each produce about 9%. Other source only a decade ago cited both Chile and Norway with about 30+% of the production. The latest comparisons (two source) I could find says that Chile produces about 600 metric tons and Norway about 1,300 tons of Atlantic salmon annually. As salmon aquaculture has become large and international business, the companies from Norway, the United States, Scotland, and Chile and elsewhere, are now growing fish outside their original national waters. Much of the Scotland fishery is owned by Norwegian companies and so on. One company, Marine Harvest, kills/processes well over 380,620 tons of salmon annually; 7,000 tons or so a week or about a ton of salmon processed each day; nearly half the world’s production.
Anyway here is a quick walk through a floating salmon farm. Most actual growing areas are kind of stand alone feature (floating pens) out in the deep water of a fjord. This one is designed as an educational site.