Mass seed production of Korean rockfish Sebastes schlegelii at Ulleungdo

Abstract

In order to investigate the possibility of mass seed production of Korean rockfish (Sebastes schlegelii) in Ulleungdo, seed production was carried out from March 31, 2018 to June 10, 2018 at hatchery located in Hyeonpo, Ulleungdo. The broodstock of Korean rockfish used in the seed production were 20 individuals of 3 years old, about 2 kg. The seed production continued for 24 hours in a 10-ton rearing tank and stocked at a density of 15,000 individuals /m3. The rotifer cultivated in the 20-ton tank was supplied with concentrated chlorella, and it was supplied to fingerling of S. schlegelii with density of 6.8 (1-4 days after parturition), 17.0 (5-7 days), 27.2 (8-10 days), 13.6 (10-13 days) and 6.8 individuals per mL (14-17 days), respectively. The artemia hatched in the 500-L tank, and it was supplied to fingerling of S. schlegelii with 60 g (dry egg weight basis, 10-13 days after parturition), 120 g (14-17 days), 150 g (18-29 days) and 200-425 g (30-34 days), and 510 g per day (35-43 days), respectively. Commercial feed (Aller Futura Larvae EX 0 GR + Love Larvae No. 1) were supplied from the 18th day after parturition with 240 g (24-29 days after parturition), 150 g (30- 34 days), 200-425 g (30-34 days) and 510 g per day (35-43 days), respectively. During the seed production period, debris was removed with a siphon up to 5 days and then flow rate increased to 5-6 times per day at 70 days. During the seed production stock of Korean rockfish used in the seed production were 20 individuals of 3 years old, about 2 kg. The seed production continued for 24 hours in a 10-ton rearing tank and stocked at a density of 15,000 individuals /m3. The rotifer cultivated in the 20-ton tank was supplied with concentrated chlorella, and it was supplied to fingerling of S. schlegelii with density of 6.8 (1-4 days after parturition), 17.0 (5-7 days), 27.2 (8-10 days), 13.6 (10-13 days) and 6.8 individuals per mL (14-17 days), respectively. The artemia hatched in the 500-L tank, and it was supplied to fingerling of S. schlegelii with 60 g (dry egg weight basis, 10-13 days after parturition), 120 g (14-17 days), 150 g (18-29 days) and 200-425 g (30-34 days), and 510 g per day (35-43 days), respectively. Commercial feed (Aller Futura Larvae EX 0 GR + Love Larvae No. 1) were supplied from the 18th day after parturition with 240 g (24-29 days after parturition), 150 g (30- 34 days), 200-425 g (30-34 days) and 510 g per day (35-43 days), respectively. During the seed production period, debris was removed with a siphon up to 5 days and then flow rate increased to 5-6 times per day at 70 days. During the seed production