Can tidal power affect fish?

Can tidal power affect fish? - By Fiskeriforskning - Statkraft is focusing on tidal power and is planning a floating plant in Kvalsundet Strait outside Troms. Can such a power plant affect fish farms and the local fish population?

Foto: Frank Gregersen, Fiskeriforskning.

Tidal power is a fully renewable and environmentally friendly source of energy, and the power company Statkraft will now test a floating, underwater power plant outside Troms. But can such a tidal power plant affect the fish population in the area?

Scientists at Fiskeriforskning indicate in a new report that it is uncertain what effects such a plant will have on the life in the sea around the power plant.

Artificial reef

Illustration: The Statkraft Group

Shipwrecks are often the fish's favourite places in the sea because they provide good protection against predator fish. And this plant can work in this same way with its 55-metre width and 38-metre length. But the plant, which can provide protection for the fish, can also be a problem for the fish in the area.

"We still do not know what is going to happen", says Scientist yvind Aas-Hansen at Fiskeriforskning.

"It is not certain that the fish are going to hear the sounds from the power plant at all", he says, "and then it is possible that the fish will collide with the rotor blades. This can also be a problem if the fish are attracted by the sounds from the plant."

Frightened away by the sounds?

Aas-Hansen stresses that it is also possible that the fish will be frightened away by the sounds from the power plant. If this happens, the area around the plant can become fish-free. It is also possible that the sounds can affect the fish in nearby fish farms.

"If the plant produces low-frequency sounds, it can scare the fish with good hearing, like cod, from passing through the strait", he says.

"On the other hand, the power plant is not permanently affixed to the seafloor, so it is possible to move it as needed or to reduce the side effects."

According to the plans, the tidal power plant will be placed in KvalsundetStrait for two years before an impact study is prepared around the operation of the plant. It can be of interest to measure the effects on the fish population at the Aquaculture Research Station in Troms, which is close to the planned power plant. This way, a model can be developed that also can say something about the effect on the life in the sea when placing these power plants in other places along the coast.

Source: Fiskeriforskning - 8th March 2006