ISSN : 1225-3480
일본산에서 이식한 종패의 성장과 한국산 굴의 성장을 조사하고자 1995년 6월부터 12월까지 경상남도 통영시 북만해역에 두 종패를 수하하여 패각 및 육성장을 조사하였다. 조사기간 중 수온은 표층 11.2-27.8<TEX>$^{\circ}C$</TEX> (평균 19.84 <TEX>$\pm$</TEX> 5.47<TEX>$^{\circ}C$</TEX>), 저층11.1-23.6<TEX>$^{\circ}C$</TEX> (18.31 <TEX>$\pm$</TEX> 4.18<TEX>$^{\circ}C$</TEX>) 였고, 염분은 표층 31.45-34.57 (평균 33.10 <TEX>$\pm$</TEX> 1.16), 저층 31.69-34.35 (평균 33.24<TEX>$\pm$</TEX> 1.06) 이었으며, 월별로는 9, 10월이 가장 낮았고, 12월이 가장 높았다. 클로로필은 1.66-2.67 mg/㎥ (평균 2.01 <TEX>$\pm$</TEX>0.36 mg/m<TEX>$^3$</TEX>) 의 범위였으며, 11월이 1.66 mg/<TEX>$^3$</TEX>으로 가장 낮았다. 패각 성장은 일본산이 한국산 보다 월등히 높은 성장량을 나타내어 12월 수확시 한국산은 70.3 <TEX>$\pm$</TEX> 12.5 mm, 일본산은 96.2 <TEX>$\pm$</TEX> 14.6 mm였다. 6-7월간의 성장이 가장 빨랐고, 한국산은 10월 이후 패각성장이 둔화된 반면, 일본산은 11월 이후 다시 급격한 성장을 하였다. 육중량은 9월까지 한국산과 일본산은 거의 비슷하였으나, 9월 이후 현저하게 차이가 나타나기 시작하였다. 12월 수확시한국산 4.6 <TEX>$\pm$</TEX> 1.9 g, 일본산 7.5 <TEX>$\pm$</TEX> 2.9 g으로 일본산의 육성장이 양호하였다. 그러나 일본산은 11월에 8.1 <TEX>$\pm$</TEX> 3.0 g으로 가장 높은 육중량을 나타내었다가 12월에 다시 감소하였는데, 이는 먹이량에 의한 양식장의 수용력에 의해 조절된 것 같다(정, 1998). 한국산은 산란 후 회복이 느려 10월까지 비만도가 감소한 반면, 일본산은 9월부터 다소 증가하기 시작하여 10월 이후 급증하였고, 11-12월에 다시 급격히 감소하였다. 12월 수확시 비만도를 보면, 한국산은 12.8, 일본산은 15.3으로 일본산이 훨씬 높았다. 이상의 결과로 볼 때, 일본에서 이식한 종패의 성장이 모든면에서 한국산보다 우수하였다. 북만에 수하 양성한 한국산 및 일본산 굴 종패의 각고-각장 상관식은 아래와 같다. Korean oysters: S<TEX>$_{h}$</TEX> = 2.922St - 4.8024 (<TEX>$r^2$</TEX>= 0.8541) Japanese oysters: S<TEX>$_{h}$</TEX> = 3.623St - 5.1239 (<TEX>$r^2$</TEX>= 0.7782) Bae et al. (1976)과 Lee et al. (1992)이 보고한 한국산 종패의 각고-각장 상관식과는 기울기 차이가 현저하여 각고의 길이가 늘어나 일본산 종패 이식이후 한국산 굴의 형태적 변화가 있음을 알 수 있었다.
To study the growth of transplanted Pacific oysters, Crassostrea gigas, we sampled Korean and Japanese oysters attached in Chinhae Bay near Gaduk Island and in Seto inland sea in Japan, respectively, suspended in Pukman Bay. Water Temperature ranged from 11.2 to 27.8<TEX>$^{\circ}C$</TEX> (mean 19.84 <TEX>${\pm}$</TEX> 5.47<TEX>$^{\circ}C$</TEX>) on the surface, and 11.1 to 23.6<TEX>$^{\circ}C$</TEX> (mean 18.31 <TEX>${\pm}$</TEX> 4.18<TEX>$^{\circ}C$</TEX>) on the bottom. Salinity ranged from 31.45 to 34.57 (mean 33.10 <TEX>${\pm}$</TEX> 1.16) on the surface, and from 31.69 to 34.35 (mean 33.24 <TEX>${\pm}$</TEX> 1.06) on the bottom. salinity was the lowest in September and October, and the highest in December. Growth of oysters in shell height showed a significant difference after being suspended at the farm, reaching 70.3 <TEX>${\pm}$</TEX> 12.5 mm in the Korean oysters and 96.2 <TEX>${\pm}$</TEX> 14.6 mm in the Japanese oysters in December. While the Korean oysters showed relatively low growth rate and cessation of growth after sudden growth between June and July, the Japanese oysters showed continuous growth during the whole farming period, although stepwise growth was observed. It was not until September that meat weight showed a significant difference between the two. After September, there was a sudden increase in the Japanese oysters, reaching 7.5 <TEX>${\pm}$</TEX> 2.9 g in December, but growth of the Korean oysters showed slow growth rate during whole farming period, reaching 4.6 <TEX>${\pm}$</TEX> 1.9 g in December. here was an obvious decrease in the meat weight of Japanese oysters in December, which might be attributed to restriction of food. Condition factors rebounded in October in the Korean oysters and in September in the Japanese oysters, respectively, attaining 12.8 in the Korean oysters and 15.3 in the Japanese oysters at the end of investigation on December. Shell length-height regression equations were as follows: Korean oysters: S<TEX>$\sub$</TEX>h/=2.922S<TEX>$\sub$</TEX>t/,-4.8024 (r<TEX>$^2$</TEX>= 0.8541) Japanese oysters: S<TEX>$\sub$</TEX>t/=3.623S<TEX>$\sub$</TEX>h/,-5.1239 (r<TEX>$^2$</TEX>=0.7782) This showed the possibility of morphological transformation in the shell of the Korean oysters since shell height was longer than those reported by Bae et al. (1976) and Lee et al. (1992).
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