ECO-Shrimp trawling

One of the main arguments for semi-pelagic trawling is the potential reduction in fuel consumption. We have therefore compared the towing resistance in semi-pelagic trawling with bottom trawling. One measure of this is the warp tension recorded by the winch control system during trawling. It should be noted that this does not provide an accurate quantitative measure of the fuel consumption directly, but it gives a relative and qualitative measure of the reduction. The results indicate a 3-4 % reduction in towing resistance for semi-pelagic trawling compared to bottom trawling, under otherwise similar conditions. Further tuning of the winch-controller can likely increase this to a 5-6 % reduction. The main objective of the project is therefore considered to be achieved, although the reduction is less than the 20 % reduction suggested initially in the project. Based on these results the project owner considered that this project had reached its potential, and decided to terminate the project by the end of 2016. It is still considered that the winch-controller developed in the project should be a future component in winch control systems, but that this is best done through new and designated R&D initiatives, where also other technology suppliers and companies are partners.

This project proposes shifting the effort from highly energy demanding bottom trawling to a more energy efficient semi-pelagic shrimp trawling technology for the exploitation of the Northern shrimp in the Barents Sea. To support this goal, the project w ill develop a trawl control system that will be based on active control of the trawl doors, remote controllable trawl doors, and integrating their operation into the active winch control systems on board the fishing vessel. Using such a system, it is poss ible to lift the nearly 40 tons of steel (18-m3 bottom trawl doors that weigh 8 tons each, and two 9-ton central clumps) from the sea bed. As a consequence, it is possible to greatly reduce the towing force, and thus the fuel consumption. This project p roposes a 20 % reduction in fuel consumption which may help turning shrimp trawling into an attractive and profitable activity again. The following issues have been identified as the main challenges for developing this new semi-pelagic triple trawl syste m: - Lift the trawl doors, central clump(s), sweeps and bridles from the seabed without losing symmetry at low towing speeds (normally 2 knots). - Keep the ground gear with proper contact with the seabed to secure catch. - Control and surveillance of the semi-pelagic triple trawl system - Utilize new sensor technology integrated into control and surveillance systems. - Develop a system with remote controllable for trawl doors for active control of pitch, roll and angle of attack. - Develop a local communication link between trawl doors' depth sensors and active control system of trawl doors. - Integrate control of trawl doors to the active winch control system on board the vessel.