Population Ecology of Korean Sand Loach Cobitis tetralineata (Pisces; Cobitidae) in the Seomjin River, Korea

Population ecology of Cobitis tetralineata was examined at Churyeong Stream, Seomjin River, Korea. C. tetralineata inhabited on the sand bottoms with $10{\sim}20cm/see$ in current velocity, and $30{\sim}150cm$ in water depth. This species was active on the sand during the daylight hours from March to October, but they hibernated in the inside of the sand during the winter season. Sex ratio of female to male was 1:0.57, and female was $20{\sim}30mm$ (TL) larger than male. The age group of C. tetralineata (female) population showed that the $20{\sim}40mm$ group is 0+ years old, the $45{\sim}65mm$ group 1+ years old, the $65{\sim}90mm$ group 2+ years old, and the group longer than 90 mm over 3 years old. Males $13{\sim}14$ months old after hatching had lamina circularis at the base of its pectoral fin as a secondary sexual character. And in its spawning season, lateral color pattern of male was changed as a sexual dimorphism. The spawning season may be from late June to middle July, $22{\sim}26^{\circ}C$ water temperature. The average number of mature eggs in ovary was about $1,288{\pm}583(474{\sim}2,976)$, egg diameter was about $0.98{\pm}0.1mm$. C. tetralineata fed mainly on Chironomidae, Arcellidae, Branchioda and Algae. The feeding rate was the highest in April and September, but they did not fed in the winter.

줄종개 Cobitis tetralineata (Pisces; Cobitidae)의 개체군 생태

줄종개, Cobitis tetralineata의 생태를 섬진강 지류인 추령천에서 조사하였다. C. tetralineata는 하상이 모래이고, 유속이 $10{\sim}20cm/see$, 수심은 $30{\sim}150cm$인 곳에 대부분 서식하였다. 활동은 낮에만 활동하는 주행성 어류로 3월부터 10월까지 활동하였고, 이후 11월부터 이듬해 2월까지는 바닥 속으로 파고들어가 월동하였다. 성비는 암컷과 수컷이 1 : 0.57로 나타났고, 암컷이 수컷보다 $20{\sim}30mm$(TL)이 더 컸다. 줄종개(암컷)의 연령은 $20{\sim}40mm$가 당년생, $45{\sim}65mm$가 1년생, $65{\sim}90mm$가 2년생, 90 mm 이상이 3년생 이상으로 추정되었다. 부화 후 $13{\sim}14$개월 이후에 수컷 가슴지느러미 제2기조에 골질반이 형성되어 암수가 구별되었으며, 또한 수컷은 산란시기에 반문변 이가 일어났다. 산란시기는 수온이 $22{\sim}26^{\circ}C$인 6월 말부터 7월 중순으로 추정되었고, 포란수는 $1,288{\pm}583(474{\sim}2,976)$개, 난경은 $0.98{\pm}0.1mm$이었다. 섭식은 주로 깔다구류, 꽃병벌레류, 물벼룩류, 조류 등을 섭식하였으며, 섭식률은 4월과 9월에 높게 나타났고 월동기에는 섭식하지 않았다.