Aquaculture​—Fish as “Livestock”

BY AWAKE! CORRESPONDENT IN NORWAY

THOUSANDS of years ago, the Chinese and the Egyptians made freshwater ponds where they kept and perhaps also fed live fish. Nowadays the tending of fish has become an industry. It is called aquaculture. Webster’s Ninth New Collegiate Dictionary defines it as “the cultivation of the natural produce of water.” This involves the creating of proper growth conditions and the stocking and farming of aquatic animals and plants in salt water or fresh water.

So far, intensive farming and stocking of fish are the more common forms of aquaculture. In many countries, especially where freshwater temperatures are relatively high, farming of freshwater fish in vats and ponds is widespread. Other nations have concentrated more on utilizing their marine areas. Norway is an example of the latter. With one of the longest coastlines in the world, appropriate sea temperatures, and comparatively pure water, this country has a natural advantage in fish farming in seawater. Norway has been a pioneer country, especially in farming Atlantic salmon and trout in the sea.

From Roe to Fish for the Market

Production starts at the hatchery in the autumn. Females are “stroked” for their roe, and the roe is fertilized with sperm from selected males. The fertilized roe spends the winter under careful supervision in the hatchery, and hatching takes place in six months. For the first few weeks, the fry is nourished from the yolk sac on its stomach; then the first careful feeding begins. In the wild state, a salmon fry spends from two to five years in the river where it was hatched, before migrating to the more nutritious sea to graze. In a hatchery the fry develops into a smolt (a salmonid fish ready for migration) in one and a half years.

The fish are then moved from fresh water to salt water. Usually they are placed in installations, floating pens or cages, in the sea. After a year or two in the sea farm, the salmon have reached proper size and are taken up for processing. It all sounds so simple, so easy. However, having fish as “livestock” presents a number of challenges.a

Biological Puzzles and Variables

Early fish farmers started from scratch and had to gain a thorough knowledge of the propagation, food preferences, and instincts of the different species. There seemed to be an infinite number of unsolved biological puzzles and things that could go wrong. Would it ever be possible to satisfy the constantly varying requirements of fry and fish regarding water quality, temperature, food, and light?

Many of these problems have long been solved. A number of today’s research programs focus on how growth and behavior of the different species might be controlled by such factors as exercise, manipulation of light, and proper quantity and quality of food.

Pollution and Algae Invasions

A clean environment is important in fish farming. Unbalanced ecosystems and pollution levels create problems in the aquaculture industry. Wild fish that detect toxicants in the water try to avoid the danger. Fish reared in sea farms cannot, being confined in pens. Oil spills or discharges of toxic chemicals are thus potentially disastrous for fish farms.

Some got quite a shock in 1988 when there was a staggering bloom of toxic algae along the southwestern coast of Sweden and off the shores of southern Norway. In vast areas algae killed fish and other life in the sea. Several fish farms were emptied, partly because of the algae itself and partly because of emergency butchering. But most installations were saved from the algal death as the fish farmers towed the pens into the safety of the fjords. Some called this algal disaster “the maritime Chernobyl,” and experts claimed that increasing pollution was probably a contributing factor in causing the bloom.

Fish pens in the sea are exposed to all kinds of weather and must withstand ice, rough seas, and storms. When an installation is wrecked and the fish escape, the fish farmer loses valuable property. Moreover, escaped fish might spread diseases to wild fish, and this has been a serious problem. Escaped fish will also compete with wild fish for food and spawning grounds, and there is a fear that this might have a negative influence on local stocks.

So there is complete agreement that sea installations must be better secured to prevent escapes. Advances have been made in this area too. Aquaculture in Norway says that in recent years “a great deal [has been achieved] when it comes to making aquaculture installations able to withstand extreme weather.”

Management of Diseases

Everything that conflicts with the nature of the fish or deviates from their normal environment causes stress, and this harms their immune system. A combination of factors, such as high concentrations of fish, intensive feeding, accumulation of organic matter, and increased amounts of various fish pathogens, has generated far more serious disease problems among cultivated fish than among wild fish. This has caused great losses to the industry.

Indeed, many of these fish diseases might be treated with, for example, antibiotics, but prolonged use of antibiotics is a threat to the environment, primarily because it produces resistant bacteria, requiring the development of new medicines. Drugs may also weaken the fish, making them more vulnerable to other diseases. The fish farmers have, of course, wanted to escape from this vicious circle.b

The old saying that prevention is better than cure therefore applies also to fish farming. Great effort has been expended to gain more knowledge on how to strengthen the natural defenses of the fish. This research is directed toward such areas as the optimization of feeding, the rearing environment and working routines, the breeding of particularly disease-​resistant fish, and the development of effective vaccines and vaccination methods. This work has brought results, and it seems that the fish-​farming industry has got the upper hand in the fight against disease.

A Growth Industry

Aquaculture is a typical regional industry of great importance to a number of coastal settlements. Since the aquaculture industry was established, amazing growth has taken place. In 1990, worldwide production had a total value of more than $23 billion. Norway supplies more than half of the world’s farmed Atlantic salmon, exporting salmon to over 90 countries around the globe.

Although Atlantic salmon has been the main product from sea farming so far, already there are limited quantities of farmed cod and halibut on the market. The aquaculture industry wishes to become a reliable supplier of fresh, quality fish year-​round.

Sadly, humans often allow themselves to be impelled by greed, and this has sometimes occurred in the aquaculture industry. In some cases environmental considerations have given way to the desire to make a quick profit. Aquaculturists with such thinking need to learn how quickly nature can strike back; they should recognize that caring for the environment is in their own interest. Sooner or later, it always proves to be wise to administer the earth’s resources in agreement with the Creator’s original purpose​—in harmony with nature and its complex ecosystems.

[Footnotes]

[Pictures on page 15]

Fish are placed in floating pens in the sea

Females are stroked for their roe

When the fish reach the proper size, they are taken up and processed

[Credit Line]

Photos: Vidar Vassvik/​Norwegian Seafood Export Council