Norwegian scientists mapping where escaped cod go – Fishupdate.com

Norwegian scientists mapping where escaped cod go Published:  23 November, 2005

COD escaping from their cages can become a problem in fish farms, as is the case for salmon. Therefore Norwegian scientists want to forestall the escapees, and are now in the process of mapping where the cod goes as making escape-proof fish farming cages has proved difficult. Scientists at the Norwegian research institute Fiskeriforskning and the Norwegian Institute for Nature Research (NINA) are collaborating to discover the cod’s escape pattern, and 25 farmed cod are predicted to provide the answer. Each of the selected cod had a small acoustic transmitter implanted in its belly and was then released in Balsfjord in Troms. The transmitters emit an audio signal that is unique for each fish, and a number of sound buoys in the sea register the signals as the cod swim by. They are also tracked from boats. The scientists can then find out where and when the fish have moved after release. The technology is brand new, and has never been used on farmed cod.

“The goal is to find out where the escaping cod go and whether this technology can make it easier to capture escaped cod”, Scientist Pål Arne Bjørn at Fiskeriforskning said.

If fish escape from fish farms, the farmers can suffer large economic losses. Cod breeding is a rather new industry, and escaping cod are not now a problem. But we still know from experience from salmon farming that escape can become a considerable challenge. Fiskeriforskning’s earlier studies also show that cod are far more inclined to escape through holes in the cage than salmon.

The tests will give us knowledge about how we can adapt the technology and have better monitoring and recapture of escaped cod. The new knowledge will also be used to evaluate potential environmental consequences for the ecosystem.

The project is a collaboration between Fiskeriforskning, NINA, the Canadian universities The University of British Columbia and Memorial University of Newfoundland, and Laponia Seafoods. The project is financed by the Research Council of Norway.

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