전자저널 > 전자저널 > Spawning, Hatching, Survival and Cannibalism of Octopus ocellatus

Spawning, Hatching, Survival and Cannibalism of Octopus ocellatus

Byung Gyun Kim, Ee Yung Chung, Je Cheon Jun and Chi Hong Kim

Puan Marine Hatchery, National Fisheries Research & Development Institute, Puan 579-850, Korea

Spawning, hatching, survival and cannibalism of the octopus, Octopus ocellatus, were investigated at the indoor laboratory. The specimens were collected in the coastal waters of Puan, Korea, from March 2000 to May 2001. Changes in the gonadosomatic index (GSI) during March to May, 2000 were similar to those in 2001. The GSI began to increase in March and reached the maximum in May 2000 and 2001. The mean fecundity of adult individuals in April was larger than those in March and May in 2000 and 2001. In the investigations of survival rates of adults according to the water layers, the mean survival rate in the middle water layer was higher than that in the bottom layer in year 2000 (p = 0.002). The survival rate during 2001 was similar to the result of year 2000 in the water layers (p = 0.018). From the investigations with the purchase dates, the survival (88.8%) in the early spawning period (April 10, 2000) showed larger than those in the mid-spawning (May 11, 2000) and the late spawning (May 23, 2000). For aquaculture, it is suggested that the purchase timing of adults in the early spawning period will have a better result than that of the other spawning periods. In the amount of spawning with water layers, the number of eggs spawned of the adults in the middle layer were larger than those in the bottom layer. In the number of eggs spawned with the purchase dates, the number of eggs spawned in the early spawning period were larger than those in the middle and late spawning periods. The size of eggs spawned were 6.904 x 2.520 mm. the hatching period required (from spawning to hatched larvae) was 55 days (April 17 to June 7, 2000) at water temperatures of 11.2 to 21.1℃. In case of the hatching rates with water layers, the hatching rate in the middle water layer was larger than that in the bottom one (p = 0.004). In the hatching rates with the purchase timings, the hatching rates in the early and mid-spawning periods showed higher that in late spawning period. Of the three conditions for hatching of the octopus larvae, the experimental group under the conditions of the presence of adult mother and use of filtered seawater was the best hatching condition. In the rearing experiments of young octopus with the four food conditions, the survival of an experimental group fed on Artemia was the highest (21.6%). From the rearing experiment with the three kinds of the shelters for the inhibition of cannibalism, the survival of the hanging group with the oyster hanging strings was the highest.

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