Salmon farming (aquaculture of salmonids)

Salmon farming (aquaculture of salmonids) is the process of raising salmon for commercial sale. The process began in the 1960s, but it was not a successful commercial endeavor until the 1980s. Because salmon farming requires specific conditions, it can only be practiced in certain parts of the world.

The most common form of salmon farming involves keeping salmon in networks of nets off the shoreline until they are ready for harvest. While this type of farming is economically efficient and utilizes little space, it crams large numbers of fish into small spaces. Fish in such enclosures are especially vulnerable to diseases and parasites, which can affect the quality of the final product.

When diseases or populations of parasites grow within a farm, they can spread to natural populations of salmon. Populations of wild salmon in most parts of the world are badly damaged from past overfishing, and the introduction of a new threat could cause them to collapse. For this reason, many scientists are looking into a more ecologically friendly ways to farm large fish populations.

Background

Salmon farming began on a small, experimental scale in the 1960s. However, the industry took many years to catch on in an industrial sense. Major industrial salmon farms first appeared in Norway in the 1980s and then in Chile in the 1990s. From that point, it spread to Canada and Scotland. These regions tend to be the major producers of farmed salmon because of natural conditions favoring the practice. The process requires very specific environmental conditions, and many such conditions are difficult to recreate. Over time, salmon farms have spread to Iceland, Ireland, New Zealand, and Australia. As salmon farming becomes more efficient, and as demand for salmon increases, salmon farmers will continue to look for new areas in which to breed their fish.

Overview

Salmon farming is the process of raising salmon in a controlled setting. Before the widespread use of salmon farming, the vast majority of salmon had to be caught in the wild. Although humans have eaten salmon for as long as they have been able to catch large oceanic fishes, catching and selling salmon as an industry can be traced back to 1829. Indigenous tribes in Canada caught salmon and then sold it to the Hudson’s Bay Company. At first, people primarily caught salmon in rivers using spears, nets, lures, and other traps.

However, as gas-powered commercial fishing vessels became more commonplace, fishing techniques changed. These new boats used a method called trawling, in which massive nets are dragged behind ships, catching anything in their path. Trawling was extremely profitable, as it vastly increased the number of fish that a commercial vessel could catch. This caused significant overfishing, meaning that fishers took more fish from the environment than the natural populations could sustain. In the 1990s, stocks of wild salmon began to plummet. Soon, the number of wild salmon began dropping so low that commercial fishing operations could no longer make a profit. Governments began passing restrictions on salmon fishing, but most wild salmon populations had been strained beyond the point of easy recovery.

To help meet the public demand for salmon while wild populations were in a state of collapse, some people began to farm salmon. The most common form of salmon farming is called open-ocean farming. Open-ocean farming begins on land, where salmon are hatched in specialized freshwater brood hatcheries. Once they grow large enough, the salmon are transferred to ocean pens. These are large pens made of strong netting located in a natural waterway. Most pens are located in naturally sheltered areas, such as bays or fjords. The salmon continue to grow in these pens, immersed in water resembling their natural environments. Then they can easily be harvested for sale. This allows companies to sell salmon without affecting the struggling wild populations.

Many experts wonder about the sustainability of salmon farming. Keeping large amounts of salmon in small places tends to have a negative influence on the local environment. The amount of waste produced by the fish can harm the water quality. The food fed to farmed salmon also has a negative effect on both the fish themselves and their environment. In most cases, salmon are fed a diet of food made from terrestrial plants and animals. While this reduces the strain on local fish populations, it can compromise the nutritional needs of the salmon. Large amounts of fish food settling to the bottom of the ocean can also endanger local ecosystems.

When so many fish are kept together in small spaces, diseases and parasites become more commonplace. One problematic parasite common to salmon is sea lice. The parasites attach themselves to the salmon, living off the salmon’s blood and skin. Sea lice commonly carry diseases, reducing the overall health of the fish. They also make it harder for fish to maintain their saltwater balance.

In addition to the risks to farmed salmon, the ideal breeding conditions for sea lice created by salmon farming can pose a risk to wild salmon. Sea lice populations inside salmon farms increase rapidly in a short period. They can then escape through the netting of the farms, spreading to natural salmon populations. Because wild salmon populations are already critically low, any threat to their well-being becomes a serious concern.

For this reason, experts are attempting to develop more sustainable farming practices for salmon. Some suggest utilizing tank structures, or increasing the security and control of net farms. Others suggest moving farms inland, removing any chance of parasites spreading into the ocean.

Bibliography

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