Cleaner

1989/12/01 Elhuyar Zientzia Iturria: Elhuyar aldizkaria

• Arrantza

Elhuyar spoke about the problems caused by salmon crops. The previous issue of Science and Technology and two of the main problems mentioned the health and pollution of fish. In the salmon nurseries of Great Britain it is intended to use a small orange fish to deal with these two problems.

The Gailegoa fish, Ctenolabrus rupetris, eats the parasites of the nursery salmon. These parasites are crustaceans and live on the surface of the fish. They fill the skin with wounds and facilitate the attack of fish to diseases. They can also cause the skin and fish to die to the brain of the fish.

Organophosphoric pesticides are used in salmon farms to control these parasites. Every three to four weeks the baskets in which there are fish must be treated with pesticides, since the parasite reproduces very quickly. The excessive use of pesticides has significantly increased the percentage of blurred salmon eyes, as well as being harmful to living beings surrounding fish boxes.

The station can help solve the problem. It is a fish of 12 cm in length that feeds on parasites located on the surface of other fish, that is, fish cleaner. The hen is not usually with salmon in the receptions, but when placed in the boxes it starts eating parasites very quickly.

Last year the first sessions were held in Norway. In a nursery were placed 26,000 salmon next to 600 units. The salmon in this nursery did not need treatment with pesticides to maintain a good level of health. On the contrary, the group used as control had to be treated several times with pesticides.

The use of summits is, in addition to very suitable from the ecological point of view, economically beneficial, since the purchase of pesticides does not imply an economic expense.