Flatfish as aircraft passengers

Svein Tønseth
Photo: Jens Søraa

Early in this century flatfish were sent live but chilled on long trips from Trøndelag in the middle of Norway to customers in eastern parts of the country. Researchers at SINTEF and MARINTEK have modernised the almost forgotten transport method and believe that it can be used to fly live plaice to distant and lucrative markets without adding to the suffering of the fish.

Research director Leif Jørgensen puts a case for the export of live plaice.

The idea of sending flatfish as aircraft passengers came with the realization that high prices are paid for live flatfish in other continents. In Asia, for example, live fish can fetch 30 times the price paid for fish that have been killed.

In the olden days, fishermen from Inderøy near Trondheim, Norway, sent plaice in cases surrounded by seaweed and ice. The chilling reduced the fish's metabolism and oxygen requirements. By using this method, the fishermen kept the fish alive despite the small amount of water in the transport cases.

Some years ago, Leif Jørgensen, research director for aquaculture at SINTEF Applied Chemistry, was an obstetric aid for plaice juveniles produced for research purposes in Mosvik, North Trøndelag. His task was to transport parent fish between the juvenile installation at Mosvik and the university's biological station in Trondheim. As he needed a transportation method, he contacted the ageing fishermen who knew about the transportation of live fish from Inderøy.

SINTEF researchers replaced the seaweed with man-made materials, but the ice was retained. Using this method they also managed to keep the fish alive with only small amounts of water in the cases. This method of transportation made it more interesting and viable to consider air transport.

Here was a solution that required neither expensive transportation of large amounts of water nor complicated containers with water treatment equipment. The transportation to and from Mosvik took up to six hours and was carried out under controlled conditions. The water temperature and oxygen content were both continuously monitored, and the fish emerged in fine form.

Since then, Jørgensen and his colleagues have carried out a succession of projects dedicated to the transportation of live fish to gauge what type of transport conditions are most suited to the fish.

Among other things, they have used magnetic resonance (MR) technology most people know from medical examinations to analyse what happens to fish's muscular cells during simulated transportation. By using this method, possible stress reactions in the plaice can be chemically read.

"We have seen that the well-being of the fish is more reliant on the quality and temperature of the water than on the amount of water that is used," says Jørgensen. "The MR research shows that the fish are calm as long as the temperature and quality of the water is correct."

If the transportation of live plaice takes off, Jørgensen believes there is a future for Norwegian plaice breeding.

"We are mastering the technology concerning both juvenile fish and production methods for the developing phase."