Double Nets Are Not a Lasting Solution for Cod

5 July 2012, at 1:00am

NORWAY - Double standard multi-filament nylon thread will not constitute a lasting solution to prevent escapes of fish from aquaculture, according to a report by SINTEF that has been prepared on behalf of the Directorate of Fisheries.

Farmed cod can bite through traditional nylon nets and escape. From an environmental perspective this is very unfortunate, and the fisheries authorities have had to assess whether there is a good initiative to require the use of double nets.

The report pointed out various measures to ensure a sustainable aquaculture industry and it questioned about whether the use of double nets is appropriate.

SINTEF states in the report that there is little public knowledge about this subject. The conclusions are based largely on interviews with industry practitioners who have had experience with this type of net.

The main conclusion was that a double standard multi-filament nylon thread will not constitute a lasting solution to prevent the escape of cod.

Both nets will be exposed to plucking/chewing from cod and are equally vulnerable to breaches because of bad weather.

The introduction of such a measure will therefore not eliminate escapes.

Oerations with double nets will be more complex and this can increase the number of escape events.

For cod, it is more probable that new material of powerful monofilament or other type of "line" will be a much more effective at preventing escapes.

The report also showed that operating and investment costs will be considerably higher if one uses a double net.

A positive gain of installing a double net is that the farmer can get an early warning of holes in the settings memo.