Monitoring recent technology changes in the Norwegian trawl fishery for gadoids

Two recent developments in the Norwegian trawl fleet for gadods are the increased use of twin rigged trawls and increased sweep angles when using single rigged trawl. There have been claims that the use of twin trawl in the Norwegian gadoid fishery signi ficantly increase the catch, however, this increase in catching power has not been quantified. The increased netting area involved when two trawls are towed will increase the drag and thus fuel consumption, but to our knowledge no assessment has been made of the fuel economics of towing single vs. twin trawls. The increased sweep angles used by the Norwegian trawlers fishing for gadoids using single rigged trawls is a consequence of the practice of using larger and heavier trawl doors. According to some fishermen, the catch rates are at least as high as obtained earlier, but similar to the twin trawl the effects of higher sweep angles on the catch rates of different species and size groups have not been documented. This project will quantify the differe nce in catch rates and engineering performance (included fuel consumption) between twin and single rigged trawls. In addition, provide information on the relative efficiency of a trawl with different sweep angles.