Studies on Propagation of Ezo Abalone, Haliotis discus hannai INO-I : Analysis of the Relationship between Transplantation and Catch in Funka Bay Coast
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Ezo abalones did not originally inhabit Funka Bay, but now live widely in this area as a result of transplantation. To six places within the Bay are transplanted 85, 450 to 1, 636, 727 seeds of abalone to give catches in these places ranging from zero to 148, 919kg. During the years of 1971 to 1976, abalone samples were collected at six stations in the bay (inhabited by Ezo abalones) and shell length, age, and growth rate of these samples were examined. The dependence of total weight on shell length as well as the relationship among various measurements of abalone shell were analyzed. Furthermore, the effects of abundance of algae and water temperature on the efficiency of transplantation were investigated. Most of the samples had shell lengths of 7 to 9cm. Oshamanbe, Toyoura and Usu often produced abalones having shell lengths larger than 11cm. Four to six year old shells constituted the main age group. Only a few samples were older than 10 years. Toyoura was found to provide the fastest growth rate: 9.6cm in four years, 12cm in six years, 13cm in eight years and 14cm in ten years. Abalones feed on some kinds of algae. Undaria Pinnatifidaf. distans, Desmarestia viridis and Ulva pertusa are available to depths as deep as 10m in most of the places studied. However no useful algae live beyond 5m depth in Okushiri. Water temperature in the shallow areas within the Bay does not drop to 3°C even in winter, namely between January and March. We cannot find abalone in places where the water temperature is below 3°C winter. The survival rate of transplanted abalones within the Bay was estimated to be 25 to 30% after two years of transplantation based on the ratio of transplantation to catch as well as on the proportion of the first generation abalones found in the sample.
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関連論文
- エゾアワビ0令個体の出現とその成長〔英文〕
- Studies on Propagation of Ezo Abalone, Haliotis discus hannai INO-I : Analysis of the Relationship between Transplantation and Catch in Funka Bay Coast