Abstract
The experiment was performed to evaluate the possibility of utilizing underground sea water for the seed production of tiger puffer, Takifugu rubripes. For this purpose, the effects of 6 different salinities (3.5, 7.0, 14.0, 20.0, 27.0, $33.0\%_{\circ}$) were determined based on the hatching rate of fertilized eggs, survival rate and the amount of food consumed by hatched larvae, where as the effects of 3 different salinities (20.0, 27.0, $33.0\%_{\circ}$) were also examined with rearing tiger puffer juvenile ($4.29{\pm}0.50$ cm in total length) for 50 days in the closed recirculating water system. As a results, either the hatching or the survival rate of more than $70.0\%$ were obtained from the fertilized eggs reared at the salinity of 27.0 to $33.0\%_{\circ}$, the early hatched larvae at 27.0 to $33.0\%_{\circ}$, and the 10-day-old larvae at 20 to $33.0\%_{\circ}$. At three different salinities, the survival rate of 20-day- and 30-day-old larvae turned out to be $89.0\%$ and $92.5\%$, respectively. The salinity for maximum food intake thus appeared to be from 27.0 to $33.0\%_{\circ}$. In this condition, 20-day-old hatched larvae consumed $323\~342$ Artemia nauplii and 30-day-old hatched larvae ate $1,559\~1,5791$ A. nauplii. The highest growth rate of fingerlings were observed at the salinity $27\%$ and followed by 33.0 and $20.0\%_{\circ}$, respectively. The relationship between the days of rearing (X) and the total length (Y) of the fingerlings were as follows : $33.0\%_{\circ}$ group : Y=0.107X-2.532 (r=0.982) $27.0\%_{\circ}$ group : Y=0.116X-3.195 (r=0.975) $20.0\%_{\circ}$ group : Y=0.116X-2.693 (r=0.987) The slopes of regression line estimated from $27.0\%_{\circ}$ and $33.0\%_{\circ}$ groups were significantly different from that of $20.0\%_{\circ}$ group.
제주도 연안의 풍부한 지하 침투 해수는 년중 수온 $16\~18^{\circ}C$로 육상 양식 용수로서 경제적 가치가 높지만 지역에 따라 저염분($20\~30\%$)을 나타내고 있다. 따라서 자주복 종묘 생산시 저염분($20\~30\%_{\circ}$)인 지하 해수의 이용 가능성 여부를 파악하기 위해 6단계의 염분 농도에서 수정난의 부화율, 발생 단계별 생존율과 포식량을 조사하고, 자주복 치어(TL $4.29{\pm}0.50$ cm)를 3단계의 염분농도로 조정된 폐쇄 순환 여과조에서 50일간 사육한 결과를 요약하면 다음과 같다. 1) 수정난은 염분 농도 $27\~33\%_{\circ}$, 부화직후의 부화자어는 $27\~33\%_{\circ}$ 그리고 부화후 10일째 자어에 있어서는 $20\~33\%_{\circ}$에서 $70\%$이상의 부화율과 생존율을 보였고, 부화후 20일째와 30일째는 모든 염분 농도에서 $89.6\%\~92.6\%$의 생존율을 보였다. 2) 발생 단계별 Artemia 유생을 최대로 포식한 염분 농도와 포식량은 부화후 20일째 자어는 $27\~33\%_{\circ}$에서 $323\~342$개체였고, 부화후 30일째 자어는 $27\~33\%_{\circ}$에서 $1,559\~1,579$개체였다. 3) 3단계 염분 농도로 조정된 순환 여과조에서 치어의 성장은 $27\%_{\circ}$가 가장 양호하였고 $33\%_{\circ},\;20\%_{\circ}$구의 순이였다. 각 염분 농도별 사육 일수(X)에 따른 전장(Y)과의 회귀직선 식은 $33.0\%_{\circ}$ group : Y=0.107X-2.352 (r=0.982) $27.0\%_{\circ}$ group : Y=0.116X-3.195 (r=0.975) $20.0\%_{\circ}$ group : Y=0.116X-2.693 (r=0.987) 각 시험구간의 기울기에 대한 유의성 검정결과 $27\~33\%_{\circ}$구와 $20\%_{\circ}$구 사이에는 유의적이였다.
(Department of Aquaculture, Cheju National University)