Spawning Site Characters in the Natural Environment of Bull-head Torrent Catfish, Ligbagrus obesus(Siluriformes: Amblycipitidae) in the Gosan Stream, Mangyeong River Water System, Korea

The spawning site characters in the natural environment of bull-head torrent catfish, Liobagrus obesus, were investigated at the part of the Gosan stream in Korea from April to October 2010 and June 2011. The sex ratio of female to male was 1 : 1.02. Spawning season was from June to July with water temperature in approximately $23^{\circ}C$. The spawning sites were covered by the boulder used upper plate and were composed of gravel and sand. One male lies with the egg mass and guards the developing embryos in the hollow below the boulder. The environmental conditions of the spawning sites were $61.4{\pm}11.97$ (50~85) cm in depth, 0.58${\pm}0.067$ (0.48~0.72) m/sec in surface water velocity, $0.46{\pm}0.098$ (0.27~0.61) m/sec in middle water velocity, $0.27{\pm}0.083$ (0.14~0.41) m/sec in bottom water velocity. The boulder width as spawning sites was $26.2{\pm}5.32$ (20~38) cm in long axis, $20.5{\pm}2.97$ (16~25) cm in short axis and $11.1{\pm}4.02$ (5~19) cm in height. The hollow underneath the boulder was $9.8{\pm}2.32$ (6~14) cm in diameter and $2.8{\pm}1.10$ (1.5~5) cm in depth. The average number of eggs in ovary was $124{\pm}27.7$ (92~180). The matured egg size was $3.40{\pm}0.078$ (3.21~3.56) mm. The average number of spawning eggs in the spawning site was $99{\pm}12.9$ (81~122).

만경강 수계 고산천에 서식하는 퉁사리 Liobagrus obesus의 자연산란장 특성

2010년 4월~10월과 2011년 6월에 전라북도 완주군 고산면의 고산천 일대에서 퉁사리의 자연산란장 특징을 밝히고자 연구를 실시하였다. 퉁사리의 성비는 1 : 1.02 (♀ : ♂)이었고 산란기는 6월에서 7월 사이로 추정되었으며 이 시기의 수온은 $23^{\circ}C$ 내외였다. 자연산란장은 넓적한 돌(boulder)이 상판으로 놓여있었고 그 돌 밑은 작은 자갈과 모래로 구성되어 있었다. 자연산란장안에는 구덩이가 파져있었고 그 중심에 난괴를 형성한 알이 위치하였으며 수컷 퉁사리 1개체가 알을 보호하고 있었다. 퉁사리의 자연산란장의 수심은 $61.4{\pm}11.97$ (50~85) cm, 표층유속은 $0.58{\pm}0.067$ (0.48~0.72) m/sec, 중층유속은 $0.46{\pm}0.098$ (0.27~0.61) m/sec, 저층유속은 $0.27{\pm}0.083$ (0.14~0.41) m/sec이었다. 산란장 상판으로 이용된 넓적한 돌(boulder)의 크기는 장경 $26.2{\pm}5.32$ (20~38) cm, 단경 $20.5{\pm}2.97$ (16~25) cm, 높이 $11.1{\pm}4.02$ (5~19) cm로 나타났으며 산란장 구덩이의 지름은 $9.8{\pm}2.32$ (6~14) cm, 깊이는 $2.8{\pm}1.10$ (1.5~5) cm이었다. 퉁사리의 평균포란수는 $124{\pm}27.7$ (92~180)개이었고 알의 크기는 $3.40{\pm}0.078$ (3.21~3.56) mm이었으며, 자연산란장내 산란된 알의 평균산란수는 $99{\pm}12.9$ (81~122)개이었다.