Fishing characters of skate ray, Raja pulchra by the offshore longline fishery in Heuksan-do, Korea

Abstract

Catches, CPUE, fishing season, disc width composition and fishing ground were studied to rebuild skate ray, Raja pulchra resource by the offshore longline fishery in Heuksan-do, Korea. Annual catches and CPUE of skate ray were increased from 2003 to 2010 (CPUE: from 2007 to 2010) continuously. The main fishing season of the skate ray was from December to next May. Disc width at 50% maturity for Raja pulchra by sex were estimated to be 65.83cm, 57.01cm by female and male respectively. The range of disc width was 22.3-112.0cm and the average disc width was 66.9cm, 60.0cm by female and male of Raja pulchra respectively during 2007-2010. Annual average of disc width of female skate ray was decreased from 2007 to 2010. The fishing grounds were formed from the coastal water off Hong-do to the coastal water off Gyeogyeolbiyeol-do, Korea. The center of fishing ground in October was formed in the northwestern coastal water off Gyeogyeolbiyeol-do and separated from that of the other months.

Geographic variations of the mottled skate, Beringraja pulchra (Liu, 1932) (Rajidae) in the Yellow and East seas based on molecular and morphometric data

“…The mottled skate is a commonly consumed and commercially important fish species in Korea, and has therefore been extensively overexploited (Jo et al., ). Consequently, the catch has declined continuously within the past 20 years, with the lowest catch of 211 tonnes in 2011 (Jo et al., ). Recognizing its overexploitation, the Korean Government included the species on the total allowable catch (TAC) species list in 2008, and where it still remains (NFRDI, ).…”

“…The International Union for the Conservation of Nature and Natural Resources (IUCN) has also designated the mottled skate as vulnerable on the IUCN Red List, based on the fact that the catch has dropped by 90% within the last 10 years in Korea (Ishihara, Wang, Tanaka, Nakaya, & Jeong, ). Various studies have been conducted to conserve and manage the mottled skate populations, focusing on their reproduction (Yeon, Hong, Park, Kim, & Cha, ), feeding (Hong et al., ), morphological characteristics of the egg capsule and juveniles (Jo et al., ), the fisheries and related hypothesis on the presence of two local populations (Jo et al., ), the development of microsatellite markers (Kang, Park, & Jo, ), and the geographic distribution of these skate populations (Jang et al., ).…”

“… Summary In order to prove the fisheries‐related hypothesis of the presence of two local populations of the mottled skate, Beringraja pulchra in the Yellow Sea (Sensu Jo et al., ), the geographic variations of 90 individuals (in molecule) and 129 individuals (in morphology) were investigated. The skates were collected from the middle Yellow Sea (Daechungdo), southern Yellow Sea (Heuksando), and the middle East Sea (Ulleungdo) using gill nets, bottom trawls and longlines.…”

Spawning Characteristics and Artificial Hatching of Female Mottled Skate, Beringraja pulchra in the West Coast of Korea

“…There have been basic research on skate species regarding taxonomic studies and classification of common names ( Jeong, 1999 , 2000 ), characteristics of R. koreana egg capsules ( Jeong & Kim, 2009 ), it's spawning periods ( Kim et al, 2005 ), and comparative analysis on egg capsule shape ( Ishihara et al, 2012 ). However, there was comparatively less research on the mottled skate ( B. pulchra ) regarding food habits ( Hong et al, 2000 ), reproduction and spawning ( Yeon et al, 1997 ), fishing characteristics by offshore long line fishery ( Jo et al, 2011 ), characteristics of multi-embryo egg capsules and larvae shape ( Jo et al, 2010 ), development on microsatellite markers ( Kang et al, 2012 ), sensory characteristics of domestic mottled skate as affected by area caught, sex and fish weight ( Jo et al, 2012 ), comparison of the nutritional properties ( Jo et al, 2013 ) were exceptions. As the mottled skate is oviparous like hens, with females producing egg capsules almost year-round, it is hard to be produced in mass quantity like other fish species.…”

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

“…가 있으며, 서해 참홍어의 생식과 식성에 관한 연구 (Yeon et al, 1997;1999), 흑산도 근해 연승어업에서 어획된 참홍어의 어획특성에 관 한 연구 (Jo et al, 2011), 홍어잡이 방식의 변천에 대한 것 (Park, 2008) 등이 연구된 바 있다. 그러 나 홍어에 대한 연구는 식성에 대한 연구 (Baeck et al, 2011;Hong et al, 2000) (Cho et al, 2000), 가자미 (Kim and Lee, 2002), 병어 (Chang et al, 2007), 문치가자미 (Kim et al, 2010)…”