• Journal of Aquaculture
• /
• v.10 no.4
• /
• pp.387-394
• /
• 1997

A total of 353 farmed rockfish, Sebastes schlegli Hilgendorf, 1880 were sampled from 3 localities on Korean coastline over a 12 month period. Full parasitological examination revealed the polypisthocotylean monogenean Micorcotyle sebastis Goto, 1894 to be abundant with infections consistently reaching over 90~100% prevalence throughout the year. A seasonal pattern in parasite abundance on the gills is evident, with the population peaking twice, the largest in winter and again in summer. While the parasitic load on the left and right gills was not dissimilar, parasites within the gill sets were found to favour settlement of the II and III gill arches. A comparison of parasite abundance with host length, revealed that the smaller length fish classes (<17cm standard body length) had significantly heavier infections than those of larger fish (>17 cm standard body length). This report represents the fist record of Microcotyle sebastis on farmed rockfish in Korean coastal waters.

• Proceedings of the Botanical Society of Korea Conference
• /
• 1995.07a
• /
• pp.133-170
• /
• 1995

The major objectives of fruit breeding lie in improvement of cultivar, easy to be cultivated and of high quality, in order to produce unexpensive, delicious fruit both for fresh fruit market and processing. Recently, fruit breeding in Korea has contributed to breeding of several superior cultivars in major fruit crops, resulting in appreciable improvement in qualities such as skin color, taste and fruit-bearing habit concerned with productivity. In spite of accomplishments mentioned above, the need for both highly disease-resistant cultivars and long-keeping, physiological disorder-resistant cultivars to meet long distance transsportation in the temperate fruit crops of apples, oriental pears, stone fruits such as peaches, and grapes grown in Korea is rapidly pressing more than ever, as cultivars of today susceptible to pests and diseases and vulnerable to physiological disorders are very expensive and time-consuming in post-harvest handling and management. Thus, imporvements made in the above problems through breeding level will lead to the really enhanced productivity in fruit industry. The major impediments of tree size, the long length of juvenile period and the highly heterogeneous genetic composition to the improvement of fruit crops are responsible for the lower amount and rate of improvements of fruit crops as compared to annuals. Considering the expected limitations of the above problems to be solved through conventional breeding methods and strategy, a turning point of breeding a near perfect cultivar would be laid down if innovative breakthroughs in biological technology will be realized in applying some of the techniques of genetic manipulation at the molecular level to the cultivar improvement of fruit crops, such as the selective insertion of DNA carrying genes that govern desirable characteristics. More than anything else, those traits such as fruiting habit deciding productivity, elements of fruit qualities conditioned by monogene, and disease-and pest-resistance of vital importance for successful fruit growing are urgently desired to be improved by advancement of biotechnology for they are more than difficult and need long period to be attained through conventional breeding method.