DEVELOPMENT OF MULTIRIG SEMI-PELAGIC TRAWLING

This project has created new knowledge and technology for semi-pelagic trawling in the Barents Sea demersal fishery. The achievements in the project have been possible because of extensive cooperation between the scientific and industrial partners. This report briefly describes the results obtained in this project. The state estimator model (the core of the Roll Royce Marine's e-Trawling system) has been developed and was validated against simulation data from a complex trawling system (double semi-pelagic trawling). The results showed good agreement between the estimator and the trawls. A trawl door control systems based on active winch control has been developed and is currently being integrated into Roll Royce Marine's e-Trawling system. Two simulations studies were conducted to verify the operation of the control system: 1) Single semi-pelagic trawl with PI control of warp lengths. The winches control the trawl door independently of the other. The starboard winch has hysteresis to avoid too much winch activity. Trawling was in straight line. 2) Double semi-pelagic Trawl with PI control of all warp lengths. Trawling was in the arc. The simulations are carried out with a trawl speed of 1.5 ms -1. The bottom is a sinusoidal with amplitude up to 0.5 m and frequency 0.025 Hz. Each winch has a total of 1,000 m warp cable. Based on the initial full scale tests carried out in 2013, we carried out follow up tests in 2014 and 2015 in order to evaluate the performance of the Semi-Circular Plate Spreading Gear (SCSG). Underwater video recordings, information collected from underwater acoustic sensors and catch comparison analysis between a traditional rockhopper gear and the SCSG helped assessing the performance of the new ground gear under commercial conditions. Generally, there was good agreement with the conclusions from earlier trials. The results showed that the SCSG functioned well and was a very stable ground gear that gently slides over the seabed. Compared to the traditional rockhopper, the SCSG showed slightly more (5-8%) spreading. Regarding the fishing efficiency, the trawl with a SCSG caught more cod and haddock than the trawl with a rockhopper gear. The herding efficiency of two semi-pelagic setups (where the sweep length with bottom contact was different) were assessed in full scale and under commercial conditions. It was estimated that the setup with the lifted sweeps captured on average 33% fewer cod than the setup that kept the sweeps at the seabed. The loss of catch for cod was length independent and significant for a length span between 41 and 104 cm. When sweeps were lifted above the seabed, herding was negatively impacted and fish were lost; in contrast, when on the seabed, the sweeps were able to herd (on average) 45% of the cod into the catch zone of the gear. Lifting the trawl doors from the seabed is thought as a positive development for this fishery. However, the results show that lifting the doors too much from the seafloor and consequently the sweeps can lead to substantial catch losses. Two full scale tests with semi-pelagic shrimp trawling were performed in November 2014 and February 2015. The objective of these experiments was to assess the effect of lifting the door from the seabed on the shrimp catch and fish bycatch. The results showed that a significant reduction of flat fish was obtained when using the semi-pelagic setup without altering the catch of shrimps.

The main objective of this project is to reduce NOx- and other environmental emissions by increasing the energy efficiency of resource-intensive maritime operations in Arctic regions. The project proposes developing a multi-rig semi-pelagic trawling techn ology to be used for a sustainable exploitation of deep-water resources such as Northern shrimp and Northeast Arctic cod. This project proposes 20-30% energy reductions by shifting from bottom trawling to multi-rig semi-pelagic trawling. Energy savings of up to 30% may mean aprox. 200 mNOK less in annual fuel costs for the Norwegian trawler fleet at an oil price at current levels. There is a great potential for increasing the annual catch of the northern shrimp by 25,000 tons, towards advised levels of TAC, representing an extra landed value of aprox. 625 mNOK. The development of multi-rig semi-pelagic technology is of importance for the Norwegian supplier industry, and its international market. The Norwegian supplier industry is in general world leadin g, and the knowledge gained in this project will contribute to the general increased competence, which is a premise for maintaining this position. The project runs for three years (Jan. 2012 - Dec. 2014) and have five working packages: - WP1: Developm ent of a multirig semi-pelagic systems. - WP2: Development of enhenced surveillance and control concept - WP3: Development of a herding system for semi pelagic multi trawling (PostDoc). - WP4: Assessing the herding efficiency in semi-pelagic multi trawli ng (PostDoc). - WP5: Evaluation of multirig semi pelagic systems. The research team will be mainly affiliated with SINTEF Fisheries and Aquaculture (SFH), the Norwegian University of Science and Technology (NTNU), the University of Tromsø (UiT), the Me morial University of Newfoundland (MUN) (Canada), and the University of Massachussets (UM) (USA)