• Korean Journal of Ichthyology
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• v.28 no.4
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• pp.273-278
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• 2016

The seasonal variations in species composition and abundance of the fish assemblage were studied in the rocky subtidal habitat around the Jam-do, Jinhae. Fish samples were collected monthly from September 2007 to July 2008 using a pot. During study, a total of 48 fish species belonging to 24 families were collected. The dominant species were Sebastes longispinis, Pseudoblennius cottoides, Sebastes inermis, Rudarius ercodes, Ditrema temminckii, Ernogrammus hexagrammus, which accounted for 71.0% of the total number of individuals collected. The number of species, number of individuals, biomass and diversity greatly fluctuated showing a peak in the number of species, number of individuals and species diversity in autumn, whereas the biomass was the highest in spring. Abundance of dominant species varied with season. S. longispinis was abundant during spring and summer, while the abundance of P. cottoides was higher during autumn and spring. S. inermis occurred with high number in September, December and May, whereas R. ercodes occurred exclusively during autumn.

• Journal of fish pathology
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• v.34 no.1
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• pp.105-110
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• 2021

We experienced mortality of dark-banded rockfish (Sebastes inermis) maintained in the rearing facility located in Gangneung, after transportation. Moribund fish showed various symptoms such as exophthalmia, skin ulcers, tail rots, gill rots, discoloration of liver with petechiae, yellowish fluid in intestines and ascites. Two different colonies were dominantly appeared after spreading the lesions on the agar plates and incubation. One isolate (SI_1) showed swarming movement on TSA, and formed yellow colonies on TCBS agar. The other (SI_2) showed no swarming motility and green colonies on TCBS agar. Both of them were Gram-negative. All of these results are similar with those of Genus Vibrio. They were identified as V. harveyi and V. gigantis by PCR with subsequent sequencing of 3 different genes (16 rDNA, recA, rpoA). V. harveyi is well-known as a serious pathogen of marine fish and invertebrates, while V. gigantis is known to be often isolated from marine invertebrates, but the pathogenicity is still unknown. We suspect V. harveyi as the cause of the mortality of dark-banded rockfish, but challenge experiments with these 2 Vibrio species are thought to be necessary to make a clear conclusion.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.567-574
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• 2022

Immunostimulating effects of fucoidan administration to rockfish Sebastes schlegelii at a concentration of 20 g/kg of diet were evaluated under high water temperature condition. The oral administration of fucoidan mixed with feed at a concentration of 20 g/kg of diet for 2 weeks increased the interleukin 1β gene in the intestine and kidney of fish by 5.7 and 6.3 times, respectively. In addition, when the water temperature was gradually increased from 24 to 31.4℃ for 2 weeks, LT₅₀ delayed by 24 h in the fucoidan treated group compared to that in the control group, and mortality also reduced. Streptococcus iniae infection at a concentration of 1.50×10⁰ CFU/fish at 28℃ delayed LT₅₀ by 12 h in the fucoidan-treated group. Furthermore, the overall survival rate was 0% in the control group and 20% in the fucoidan-treated group. This study confirmed the applicability of dietary additives such as fucoidan as an immune activator of rockfish under high temperature condition.

• Korean Journal of Ichthyology
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• v.35 no.1
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• pp.1-9
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• 2023

The morphological development of larvae and juvenile of Sebastes taczanowskii were studied. The S. taczanowskii were caught at Goseong-gun, Gangwon-do from March in 2016. Larvae beared at water temperature of 11~12℃ (mean 11.5±0.5℃). The just beared larvae were 5.25~5.96 mm (mean 5.60±0.19 mm, n=30) in total length and their mouth and anus were already opened. They began to eat rotifer and transformed to postlarvae stage. 35 days after bearing postlarvae was measured 7.16~11.4 mm (mean 9.02±1.00 mm) in total length and the tip of notochord was bent upward. 48 days after bearing juvenile was measured 9.45~18.7 mm (mean 14.4±1.75 mm) in total length with dorsal fin rays XIII, 13~15; anal fin rays III, 6~8; caudal fin rays 16.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.11
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• pp.1458-1464
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• 2007

This study was conducted to develope a new type of ready-to-eat smoked Sebastes schlegeli product with high acceptability and extended shelf-life. A Sebastes schlegeli was salted at 4% salt concentration for 6 hr at $4^{\circ}C$. The cold smoking conditions for the salted Sebastes schlegeli consisted of drying for 2 hr at $22{\sim}24^{\circ}C$ followed by smoking for 2 hr at $22{\sim}24^{\circ}C$. The warm smoking conditions for the salted Sebastes schlegeli consisted of drying for 2 hr at $22{\sim}24^{\circ}C$, smoking for 2 hr at $22{\sim}24^{\circ}C$, and smoking again for 30 min at $47{\sim}50^{\circ}C$. The rancidity of the smoked Sebastes schlegeli did not change after 1 year storage at $-20^{\circ}C$ by monitoring the iodine value, peroxide value, and acid value. The number of viable cells in the cold and warm smoked samples were counted as $7.4{\times}10^5$ and $6.2{times}10^5$ CFU/g, respectively. Viable cells were not detected after 1 year of storage at $-20^{\circ}C$. The sensory evaluations of the processed Sebastes schlegeli showed that elastic texture increased with smoking as compared to with salting. There were no significant differences between cold and warm smoking in terms of sweetness, elastic texture, color, and smoke flavor. However, for overall acceptability, preference were in the oder of cold smoked, warm smoked, and salted.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.3
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• pp.241-247
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• 2013

Yellow clay dispersion has been applied to minimize fisheries impact by the red tide Cochlodinium polykrikoides blooms in Korean coasts since 1995. The present preliminary study documents the effect of yellow clay on Korean rockfish, Sebastes schlegelii, in terms of oxygen consumption rate (OCR). The OCR in the low clay suspension (0.05 and 0.23 %, w/w) showed normal level compared to the control. In contrast, the OCR for each one of three replicates in the high clay suspension (1.16 and 5.58 %, w/w) was not returned to the previous level that clay was not treated, indicating that high clay suspension (${\geq}1.16%$, w/w) might give negative effect on Korean rockfish. Overall, this result suggests that field application of clay to control Harmful Algal Blooms (HABs) may not give impact on Korean rockfish once the clay is dispersed in a low concentration (${\leq}0.23%$). In order to understand the changes of OCR in the repeated exposure to clay, it is required to do further studies on the changes of OCR when the fish is exposed to clay repeatedly after recovery in the normal seawater.

• Molecular & Cellular Toxicology
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• v.3 no.4
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• pp.267-272
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• 2007

Environmental and anthropogenic changes affect the health and stability of marine ecosystem. In this study we aimed to identify molecular biomarkers for ecotoxicological pollutants risk assessment in the rockfish (Sebastes schlegeli). We designed primers based on conserved sequences by multiple alignments of target genes from related species, and cloned the partial cDNAs of cytochrome P450 (CYP1A1), glutathione S-transferase (GST), metallothionein (MT), superoxide dismutase (SOD), ubiquitin (UB), vitellogenin (VTG) and $\beta$-actin by reverse transcription polymerase chain reaction (RT-PCR) from S. schlegeli. Northern blot results indicated that these six genes expressions were significantly induced by benzo[a]pyrene (BaP, 1 ${\mu}M$) and that the level of each of their transcripts increased in BaP-exposed rockfish in a time-dependent manner. This study suggests that transcriptional changes in these six genes may be used for monitoring environmental exposure to polycyclic aromatic hydrocarbons (PAHs).

• Parasites, Hosts and Diseases
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• v.55 no.2
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• pp.219-224
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• 2017

In July 2012, philometrid nematodes were discovered in cultured rockfish (Sebastes schlegeli) in Cheonsuman (Bay), the Republic of Korea. The nematodes were detected in the epithelial tissues of the rockfish and were identified as Clavinema mariae based on morphological studies using light and scanning electron microscopy. They revealed the characteristics same as previously identified C. mariae, notably having a long body with narrow posterior half, no caudal projection, a cylindrical-shaped esophagus, a well-developed anterior bulbous part of the esophagus, cephalic papillae, and a dorsal esophageal gland. This is the first confirmation of C. mariae infection in rockfish in Korea.

• Applied Microscopy
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• v.26 no.3
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• pp.267-275
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• 1996

The internal ultrastructural changes of germ cells and external morphology of spermatozoon during the spermatogenesis in the rockfish, Sebastes inermis were studied using transmission and scanning electron microscope. The testis is seminiferous tubule type in internal structure. Seminiferous tubule consist of many cyst which contain numerous germ cells in same developmental stage. Spermatogonium contained a large nucleus with single nucleolus in interphase. Primary spermatocyte identified by the presence of synaptonemal complex in nucleus and the contained a number of mitochondria, endoplasmic reticula and Golgi bodies in cytoplasm. The nucleoplasm of secondary spermatocyte was more concentrated than that of the previous phase. Spermatids were more condensed in nucleus and cytoplasm, and show the long-spherical shape. In the cytoplasm of spermatid mitochondria located to lower portion of the nucleus and Golgi bodies located to upper portion, but proacrosomal granule is not appeared. The spermatozoon consist of the head and tail. No acrosome could be found in the head. The cytoplasmic collar of posterior part in sperm head contained mitochondria which surrounded axial filament. The well developed axonemal lateral fins were identified in sperm flagellum, and the axial filament of the flagellum consist of nine pairs of peripheral microtubules and one pair of central microtubules.

• Ocean and Polar Research
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• v.23 no.3
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• pp.279-284
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• 2001

The natural high productivity of temperate coastal waters in Korea can be used in advantage to reduce the feed costs for the cage-cultured marine carnivorous fish species. By using the night-lights methods an alternative of supplementary feeding strategy can be offered to the cage farmers and maintain sound environmental conditions that could enhance maximum sustainable yields. The aim of this study was to investigate the effects of night-lights which shown positive results on feeding and growth in sea cage cultured rockfish, Sebastes schlegeli. The study showed that for the water around overhead illuminated sea cage, higher zooplankton density was observed at night than during the daytime. Increased amounts of for-age, evidenced by stomach content analyses were observed in the early evening, but decreased amounts were observed in the morning and afternoon. That is, feeding activities of the fish were most intensive from midnight to dawn. In a three month feeding experiment, the results showed that night-lighted groups were superior to groups with the highest feeding efficient. This study suggested that the evidence that night-lights superimposed on only day-lights enhance growth of rockfish in sea cages during summer and winter, with timing of exposure affecting growth of juvenile fish. The capability to control the feeding behavior of marine life via manipulation and external stimuli could considerably benefit the advancement of sea cage aquaculture in coastal areas.