
The engineering and catching performances of four penaeid-trawl ground gears (all 6.95. m) were compared using a 4.41-m beam-trawl assembly designed to eliminate the confounding effects of other trawl components. Three ground gears comprised either 6- (4.5 and 3.80. kg in air and water), 8- (8.42 and 6.88. kg) or 10-mm (13.07 and 11.20. kg) stainless-steel linked chain, while the fourth was a novel design termed the 'soft-brush' (15.90 and 6.94. kg) and had a buoyed line with vertically suspended 4-mm link chain (giving 63% less bottom contact that the other treatments). The three chain and soft-brush ground gears were used during 24 deployments, producing predicted mean drags (±SE) of 25.49 (1.50), 31.28 (1.50), 39.32 (1.50) and 31.93 (1.50) kgf respectively, or 15, 18, 22 and 18% of the total system. There were no significant differences in numbers or weights of the targeted school prawns, Metapenaeus macleayi, but the predicted means were up to 16% lower in the trawls with the 6-mm ground gear. The only species significantly affected by ground gear was small (5.0-8.5. cm total length) forktail catfish, Arius graeffei, with the 6-mm catching up to 45% fewer than the 10-mm and soft-brush ground gears; a result attributed to the latter treatments having greater surface areas. The performance of the soft-brush ground gear might be improved by reducing the surface area, while still maintaining target catches and with minimal bottom contact.
670, 1104 Aquatic Science, Penaeids, Otter trawling, Ground gear, Drag
670, 1104 Aquatic Science, Penaeids, Otter trawling, Ground gear, Drag
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