Mesh size selectivity of a multi-anchored monolithic trap in Liaodong Bay
LIU Hongchao1，ZHANG Guosheng1，LI Xiansen2，ZHUANG Xin1，YIN Leiming1，LI Hongquan1，TENG Wenliang1，XING Binbin1*
1.Center for Marine Ranching Engineering Science Research of Liaoning Province, Dalian Ocean University, Dalian; 2.Key Laboratory for Sustainable Utilization of Marine Fishery Resources, Ministry of Agriculture and Rural Affairs, Shandong Provincial Key Laboratory for Fishery Resources and Eco-environment, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao
Abstract: Twenty 5 m×3.8 m multi-anchored monolithic traps with mesh size of 18 mm(control group), 25 mm, 35 mm and 45 mm were connected into a line shape, and operated in 30 miles(40°42′-40°56 N′, 121°20′-121°39′ E)from the entrance of Shuangtaizi in Liaodong Bay, China, 10 times in October 11-16, 2018 to probe into influence of mesh size on production capacity of net gear, and size and type of catch.The results showed that the total catch was reduced by 12.81% in the 25 mm trap, 51.50% in the 35 mm trap and 60.81% in the 45 mm trap compared with that in the control group, especially for the 35 mm and 45 mm test nets, without decline in the total catch of main economically important types(except shrimp).The species number of the catch was shown to be significantly reduced as the mesh size was increased, 29 species in the control trap, 24 species in the 25 mm trap, 17 in the 35 mm trap, and 14 in the 45 mm trap.Prawns Eualussinensis and Palaemongravieri, spinyhead croaker Collichthyslucidus, spottedtail goby Acanthogobiusommaturus, stone crab Charybdisjaponica, and mantis shrimp Oratosquillaoratoria were the dominant species and shrimps were released with increase in the mesh size in the four nets, with the maximal release ratio in the smallest body length group, and significantly reduction of juvenile fish in the catch, indicating that the phenomenon of bycatch was alleviated.The findings provide a theoretical basis for the structural optimization of multi-anchored monolithic nets in China.
2020, Vol. 35 
