Comparison of catches and species composition for flounders caught using gillnets, gillnets with supporting lines, and trammel nets

Abstract

To compare the catches made using gillnets, trammel nets, and gillnets with supporting lines, several experiments were conductedwith commercial vessels near Uljin and Pohang in Eastern Korea between July 2010 and May 2011. Two sets of 13 differentnets were used, including 5 panels of gillnets and trammel nets each with stretched mesh sizes of 7.6, 9.1, 10.6, 12.1, and 13.6cm and 3 panels of gillnets with a mesh size of 9.1 cm with supporting lines with different line spacing. The outer (stretched)mesh size of the trammel nets measured 51.5 cm. The target fishes of the fishing nets were various types of flounders. The catchrate of flounders was 50.7% of the total catch in weight. The total catch for all nets was 443.8 kg. The predominant species waspointhead flounder (Cleisthenes pinetorum). The total catch by trammel nets was 1.4 times that of the comparable gillnets. Butmore pointhead flounder were caught by gillnets than by trammel nets, though there was no significant difference. Fishermencatching the pointhead flounder in Korea said that there was no need to use trammel net to catch it; this was an unexpectedfinding compared to the findings of other flounder fisheries. The amounts of roughscale sole, brown sole, and blackfin floundercaught by trammel nets were greater than those caught by gillnets. The mean lengths (standard deviation) of blackfin flounder,pointhead flounder, brown sole, and roughscale sole were 21.0 (4.57), 22.9 (3.40), 24.7 (4.90), and 28.3 (5.43) cm, respectively;there were significant differences in mean length (p < 0.00001). Therefore, in order to catch flounder efficiently, the fishing netsand mesh size should be chosen according to the target species. One advantage of using supporting lines is that it prevents breakageby strengthening the material especially when utilized on a rough bottom. Catch by using gillnet with supporting lines wasnot greater than that by using trammel net for the conservation of fisheries resources.