MultiSEPT - Full scale tests of the semicircular spreading gear (SCSG)

Abstract

This reportdescribes full scale tests at sea with the semi-circular spreading gear (SCSG). This activity is part of Work Package 3 (WP3: Development of new ground gear) of the MultiSEPT project. The spreading of the SCSG and rockhopper gear was measured by useof MARPORT distance sensors. Bottom contact was monitored by use of SCANMARtrawl sensors and by underwater cameras mounted in the headline and bellyof the trawl. Fishing efficiency of these two gears was assessed by comparing the size distributions of fish caught by each gear. The results showed that the spreading (distance between wing-ends)was approximately 7 % higher with the SCSG than with the rockhopper gear for the same door spreading. The SCSGhad good bottom contact and passed bottom obstacles (e.g. stones) easily. The size distribution of fish caught with the SCSG was very similar to that caught with the rockhopper, but apparently more cod (over 65 cm) and more haddock (of all sizes) was caught by this gear. However, the number of hauls performedwith the SCSP and with the rockhopper was too small to draw a clear conclusionon catch efficiency. The SCSGis a gear that is easy to rig and handle on deck, it does not require accurate adjustments, it has few control points, it has low weightand the results indicate that its performance at sea is comparable or better than the rockhopper gear for the given bottom conditions. Further development of the SCSG should emphasise on the choice of material that can reduces wear ofthe gear and the extent its life.