Mesh selectivity of multifilament nylon gillnet for ocellate spot skate (Okamejei kenojei) in the western sea of Korea

Abstract

To estimate the mesh selectivity of gillnet for ocellate spot skate (Okamejei kenojei), the field tests were carried out 12 times with six different mesh sizes (121.2mm, 137.7mm, 151.5mm, 168.3mm, 178.2mm, 189.4mm) in the coastal waters of Taean, Chungcheongnamdo of Korea, 2010-2011. In the field tests, the total number of species was 31, and that of catch was 1,410 and the total weight was 618,006g. The number and weight of ocellate spot skate which is main target in this study were 1,004 and 434,592g, respectively. The catch in number of ocellate spot skate occupied about 71.2% in total catch. The others of catch species were marbled sole (8.4%), sea raven (4.4%), japanese swimming crab (4.2%) and flatfish (4.1%) and so on. The range of body disk width (DW) of ocellate spot skates which were caught in this study was 15.2-35cm and the mode was 27-29cm. The estimation equation of mesh selectivity using the extended Kitahara' s method was expressed as s (R)〓s (DW/m)〓exp{(-0.56R 3-1.80R 2 + 12.96R-9.99)-4.26}. The optimum value of DW/m for 1.0 of retention probability in this estimation equation was estimated 1.899 and DW/m was estimated to be 1.194, 1.314, 1.395, 1.461 and 1.520 when the retention probability were 0.1, 0.2, 0.3, 0.4 and 0.5, respectively. When applied to the retention probability of 0.5, the optimum mesh size was estimated to be 177.0mm on first maturity disk width 26.9cm of ocellate spot skate.

A Machine Learning Technique for Deriving the Optimal Mesh Size of a Gizzard Shad (Konosirus punctatus) Gillnet

“…Concerning fishery resource protection, most studies estimate the selectivity curve using body length information (maturity level) of fished individuals and then derive an appropriate mesh size from this [5,7,8,10]. Conversely, Kim et al [38] derived an appropriate mesh size by considering economic aspects rather than mature individuals.…”

“…Gillnets work in the following three ways: sticking, entangling and confining the gills of the target species into the net. Gillnet gear is widely used to identify the species and length characteristics of catches [4][5][6][7][8][9][10][11][12][13]. Furthermore, gillnet materials and fishing methods differ depending on the country, region, and target species.…”

“…The selectivity of gillnets is currently studied through the modification of the gear material [4,9] or previous studies focused on different target species mesh sizes [2,5,7,8,[10][11][12][13][15][16][17].…”

A machine learning technique for deriving the optimal mesh size of a gizzard shad (Konosirus punctatus) gillnet

“…Currently, studies on the selectivity of gillnets modify the shing gear material (Yokata et al 2001; Kim et al 2015) or alter the mesh size (Park et al 2004; Kim et al 2013; An et al 2013;Park et al 2016; Ramírez-Amaro and Galván-Magaña 2019). In addition, these studies observed diverse target species, including gizzard shad (Konosirus punctatus), ocellate spot skate (Okamejei kenojei), Paci c herring (Clupea pallasii), and marbled sole (Pleuronectes yokohamae).…”