ISSN : 1225-3480
<P> 본 연구는 해상가두리에서 양성중인 2년생 북방전복의 최적 사양관리 기준을 탐색하는 것이 목적으로 수용밀도, 먹이공급량 그리고 청소 빈도의 차이에 의한 전복의 성장과 생존을 조 사하기 위해 수행되었다. 실험에 사용한 가두리의 규격은 2.4m × 2.4m × 5.0m 크기였고, 12절 그물코를 사용하였으며, 전복의 평균 크기는 각장 64.7 ± 0.7 mm, 중량 38.3 ± 2.2 g 이었다. 사육 밀도는 가두리 1칸 당 800, 1,100, 2,000 마리였고, 먹이 공급량은 한 가두리 당 1.3, 2.0, 3.0, 6.0 kgㆍday<SUP>-1</SUP> 을 공급하였다. 가두리 청소 횟수는 1회ㆍmonth<SUP>-1</SUP>, 0.5회ㆍ month<SUP>-1</SUP>, 미청소 실험구였다. 실험종료 시 사육 밀도의 경우 가장 밀도가 높았던 2,000 마리 실험구의 무게 성장이 다른 실험구들보다 유의하게 낮았지만, 생존율에서는 차이를 보이지 않았다. 가두리 청소 빈도는 전복의 성장과 생존에 모두 영향을 미쳤는데, 성장은 한 달에 1회 청소하는 실험구에서 가장 높았고 생존율은 한번도 청소를 하지 않은 실험구가 가장 낮았 다. 먹이공급량 실험에서 2 kgㆍday<SUP>-1</SUP>와 6 kgㆍday<SUP>-1</SUP> 공급한 실험구들 사이에서 유의한 차이가 없었지만, 6 kgㆍday<SUP>-1</SUP> 공급한 실험구의 생존율이 유의하게 낮아졌다. </P>
The recent decline in Manila clam landings in Korean waters is, in part, linked to a high level of infection by the protozoan parasite Perkinsus olseni. In this study, we first surveyed the infection status of protozoan parasite P. olseni in the juvenile and small Manila clams using Ray’s fluid thioglycollate medium assay (RFTM). A total of 578 clams of shell length (SL) ranging 9.2 to 29mm were collected from 9 tidal flats in Gyeonggi Bay, the coast of Taean, Garorim Bay, and Gomso Bay in January and November 2008 and March 2010. The smallest clam (SL 9.2mm) of the survey was originated from Sungam in November 2008, which was infected by P. olseni with the infection intensity of 570, 000 cells/g tissue. RFTM revealed that the juveniles (10-15 mm SL) in Gomso Bay are infected by P. olseni with a mean infection intensity of 491,000 cells/g tissue, suggested that P. olseni infection in the juveniles can be initiated as early as a few months after the settlement. The juvenile (SL 20-25 mm) and small clams (SL 25-30 mm) in Hwangdo Island were heavily infected by P. olseni, with the mean infection intensity of 1.751 x 106 and 4.830 x 106 cells/g tissue, respectively. The survey confirmed that most of the juveniles and small clams in major clam beds on the west coast were infected by P. olseni, and it is believed that P. olseni infection is not limited to the adult clams.
Chung, E.-Y., Ryou, D.-K., Lee, J.-H. (1994) Gonadal development, age and growth of the short-necked clam, Ruditapes philippinarum (Pelecypoda:Veneridae), on the coast of Kimje, Korea. Korean Journal of Malacology, 10: 38-54.
Kang, H.-S., Hong, H.-K., Yang, H.-S., Park, K.-I., Lee, T.-K., Kim, Y.-O., Choi, K.-S. (2015) Spatial variation in the reproductive effort of Manila clam Ruditapes philippinarum during spawning and effects of the protozoan parasite Perkinsus olseni infection on the reproductive effort. Ocean and Polar Research, 37:49-59 [in Korean with English abstract].
Nam, K.-W., Jeung, H.-D., Song, J.-H., Park, K.-H., Choi, K.-S., Park, K.-I. (2018) High parasite burden increases the surfacing and mortality of the Manila clam (Ruditaeps philippinarum) in intertidal sandy mudflats on the west coast of Korea during hot summer. Parasites & Vectors, 11: 1-7.
Ngo, T.T.T., Choi, K.-S. (2004) Seasonal changes of Perkinsus and Cercaria infections in the Manila clam Ruditapes philippinarum from Jeju, Korea. Aquaculture, 239: 57-68.
Park, K.-I., Choi, K.-S. (2001) Spatial distribution of the protozoan parasite Perkinsus sp. found in the Manila clams, Ruditapes philippinarum, in Korea. Aquaculture, 203: 9-22.
Park, K.-I., Figueras, A., Choi, K.-S. (2006) Application of enzyme-linked immunosorbent assay (ELISA) for the study of reproduction in the Manila clam Ruditapes philippinarum (Mollusca: Bivalvia): Ⅱ. Impacts of Perkinsus olseni on clam reproduction. Aquaculture, 251: 182-191.
Park, K.-I., Yang, H.-S., Kang, H.-S., Cho, M., Park, K.-J., Choi, K.-S. (2010) Isolation and identification of Perkinsus olseni from feces and marine sediment using immunological and molecular techniques. Journal of Invertebrate Pathology, 105: 261-269.
Pretto, T., Zambon, M., Civettini, M., Caburlotto, G., Boffo, L., Rossetti, E., Arcangeli, G. (2014) Massive mortality in Manila clams (Ruditapes philippinarum)farmed in the lagoon of Venice, caused by Perkinsus olseni. Bulletin of the European Association of Fish Pathologists, 34: 43-53.
Villalba, A., Casas, S.M., López, C., Carballal, M.J. (2005) Study of perkinsosis in the carpet shell clam Tapes decussatus in Galicia (NW Spain). Ⅱ. Temporal pattern of disease dynamics and association with clam mortality. Diseases of Aquatic Organisms, 65: 257-267.
Villalba, A., Reece, K.S., Orda, M.C., Casas, S.M., Figueras, A. (2004) Perkinsosis in molluscs: A review. Aquatic Living Resources, 17: 411-432.
Waki, T., Yoshinaga, T. (2013) Experimental challenges of juvenile and adult Manila clams with the protozoan Perkinsus olseni at different temperatures. Fisheries Science, 79: 779-786.
Waki, T., Shimokawa, J., Watanabe, S., Yoshinaga, T., Ogawa, K. (2012) Experimental challenges of wild Manila clams with Perkinsus species isolated from naturally infected wild Manila clams. Journal of Invertebrate Pathology, 111: 50-55.
Waki, T., Takahashi, M., Eki, T., Hiasa, M., Umeda, K., Karakawa, N., Yoshinaga, T. (2018) Impact of Perkinsus olseni infection on a wild population of Manila clam Ruditapes philippinarum in Ariake Bay, Japan. Journal of Invertebrate Pathology, 153:134-144.
Yang, H.-S., Park, K.-I., Donaghy, L., Adhya, M., Choi, K.-S. (2012) Temporal variation of Perkinsus olseni infection intensity in the Manila clam Ruditapes philippinarum in Gomso Bay, off the west coast of Korea. Journal of Shellfish Research, 31: 685-690.
