• 한국수산과학회지
• /
• 제45권2호
• /
• pp.97-103
• /
• 2012

This study compared the composition and texture of muscle and levels of detoxification and antioxidant enzymes in the livers of stocked and cultivated rockfish Sebastes schlegeli released after the primary culture stage in Tongyoung, South Korea. The crude lipid content of muscle was significantly higher ($P$<0.05) in cultivated rockfish than stocked rockfish, while the texture did not differ significantly ($P$>0.05). The condition factor (CF) and hepatosomatic index (HSI) did not differ significantly and the growth of stocked and cultivated rockfish was similar. The levels of the detoxification enzymes cytochrome P450 (CYP) and Ethoxyresorufin-O-deethylase (EROD) were significantly lower in the livers of stocked rockfish, perhaps because of their reduced exposure to xenobiotic compounds. In addition, stocked rockfish had a significantly ($P$<0.05) lower CAT and higher GR than cultivated rockfish, but similar levels of tGPx, SOD, GSH, and GSSG. The present study shows that the growth rates of stocked and cultivated rockfish are similar and that stocked rockfish are exposed to fewer xenobiotic compounds and less oxidative stress.

• 수산경영론집
• /
• 제46권3호
• /
• pp.119-127
• /
• 2015

This study is to analyse the causality and volatility spillover between farming fish species in consumption replacement relation using flatfish(oliver flounder) and rockfish's wholesale market price data from September 2006 to July 2015. For the analysis, VAR(5) model and bivariate asymmetric GARCH-BEKK model are employed. The empirical results of this study are summarized as follows: First, the price volatility of flatfish and rockfish is very large without the trend during the sample period. Second, the correlation coefficient between flatfish and rockfish wholesale markets has positive 0.1059 value. Third, causality relation is unidirectional from rockfish market to flatfish market. Fourth, conditional volatility spillover effect is unidirectional from rockfish market to flatfish market, but asymmetric volatility effect is bidirectional between flatfish and rockfish markets that implies the bad news arising from flatfish wholesale market impact on rockfish market's volatility and the bad news arising from rockfish wholesale market impact on flatfish market's volaltilty. Consequently, based on the thus results, the volatility spillover effect interacts and is bidirectional between flatfish and rockfish wholesale markets.

• 한국어병학회지
• /
• 제21권3호
• /
• pp.247-257
• /
• 2008

To understand the activity of non-specific defence factors in cultured Sebastes, the antibacterial effect of the serum, skin mucus and homogenate of various organs from cultured oblong rockfish (Sebastes oblongus) and rockfish(Sebastes schlegeli) against pathogenic bacteria, Aeromonas hydrophila, Edwardsiella tarda, Vibrio anguillarum, and Streptococcus sp. was compared with that of flounder(Paralichthys olivaceus) and seabass(Leteolabrax japonicus). And the activities of proteolytic enzyme, chitinolytic enzyme and haemolycin as non-specific defence factor were investigated on the oblong rockfish and rockfish. Samples from oblong rockfish showed the highest antibacterial activity by lysoplate assay on agar plate mixed with pathogens, followed in descending order by rockfish, seabass, and flounder. Turbidimetric assay was carried to evaluate the lysozyme activity of fish samples against lyophilized cells of Micrococcus lysodeiktikus. The serum, kidney, liver, stomach, intestine and eyeball of oblong rockfish and the mucus and gill of rockfish appeared to have the highest lysozyme activity among the fish strains investigated. All samples except skin mucus, liver, and eyeball of oblong rockfish and rockfish showed proteolytic enzyme activity. Chitinolytic enzyme activity was showed in random sampling and haemolytic activity was remarkable in oblong rockfish. Therefore, Sebastes strain was proved to have effective defense mechanisms based on the antibacterial activities, and lysozyme, proteolytic enzyme, chitinolytic enzyme, and haemolycin were considered to act as the non-specific defence factor of Sebastes.

• 한국수산과학회지
• /
• 제55권5호
• /
• pp.751-757
• /
• 2022

To develop a trap to prevent the catch of juvenile rockfish Sebastes inermis and bycatch, we compared the fishing characteristics of four traps with different mesh sizes (35 mm and 50 mm) and flapper connecting lines (FCL) (3 lines and 4 lines).The number of rockfish caught in trap 1 (35 mm, 4 FCL) was 200, and juvenile rockfish (15 cm or less) accounted for 49.0%. The number of rockfish caught in trap 2 (35 mm, 3 FCL) was 185, and juvenile rockfish accounted for 58.9%. The number of rockfish caught in trap 3 (50 mm, 4 FCL) was 82, and juvenile rockfish accounted for 4.9%. The number of rockfish caught in trap 4 (50 mm, 3 FCL) was 68, and juvenile rockfish accounted for 22.1%. The total catch (bycatch rate) in trap 1, trap 2, trap 3 and trap 4 was 565 (64.6%), 637(71.0%), 260 (68.5%) and 276 (75.4%), respectively. The catch per unit effort (CPUE) for juvenile rockfish in trap 1, trap 2, trap 3 and trap 4 was 0.8, 0.9, 0.0, and 0.1 individuals/trap, respectively. The CPUE of bycatch in trap 1, trap 2, trap 3 and trap 4 was 2.9, 3.6, 1.4 and 1.7 individuals/trap, respectively.

• 수산해양교육연구
• /
• 제25권6호
• /
• pp.1315-1323
• /
• 2013

The purpose of this research is to evaluate the effects of a commercial mixed extruded pellet(EP) and raw fish moist pellet(MP) diet on diseases prevalence and serological constituents and HSI of korean rockfish, Sebastes schlegeli grown in two commercial-scale aquaculture farms from June to December in 2009. The growth of MP-fed rockfish was slightly faster than EP-fed rockfish during experimental period, but did not show significant differences. The levels of TCHO, TG, Glucose and TP in the MP-fed rockfish group were higher than those of EP-fed group, whereas there was no significant difference in other biochemical factors of blood between two groups. In addition, bacteria and virus were not detected in both MP- and EP-fed rockfish groups, and the infection rates of gill fluke between two groups did not show clear difference. In conclusion, there was no comparable difference in growth and the health extents of one year rockfish by administration of the commercial mixed extruded pellet(EP) and raw fish moist pellet(MP) diets.

• 수산해양교육연구
• /
• 제27권2호
• /
• pp.390-398
• /
• 2015

A feeding experiment was conducted to determine the use of distillers dried grain (DDG) as a partial replacement for fish meal in the diet for juvenile rockfish, Sebastes schlegeli. Four iso-nitrogenous (50% crude protein) and iso-caloric (4.3 kcal/g) diets (designated as DDG0, DDG7, DDG14, and DDG21) were formulated to contain 0, 7, 14, and 21% DDG. Triplicate groups of juvenile rockfish (initial body weight, $10.2{\pm}0.2g$) were fed one of the experimental diets to visual satiety twice a day (09:00 and 17:00) for 8 weeks. At the end of the feeding trial, survival of rockfish was above 97% and not affected by dietary DDG levels (P>0.05). Weight gain, feed efficiency and daily feed intake of juvenile rockfish were significantly decreased with increase of dietary DDG levels (P<0.05). Condition factor, hepatosomatic index and visceralsomatic index of juvenile rockfish were not significantly affected by dietary DDG levels (P>0.05). No significant differences were observed in the contents of moisture, crude protein, crude lipid and ash of the whole body and dorsal muscle in juvenile rockfish fed the experimental diets (P>0.05). Therefore dietary inclusion of DDG as a replacement for fish meal could depress the growth of juvenile rockfish.

• 한국양식학회지
• /
• 제12권4호
• /
• pp.309-315
• /
• 1999

In order to understand the initial feeding time of larvae red marbled rockfish, Sebastiscus tertius changes of mouth size were investigated. Also, the fecundity of different size of red marbled rockfish broodstocks was measured. The broodstocks of red marbled rockfish, S. terius of $32.3\pm6.52 cm$ and larger than 45cm in total length spawned 296,648 and 600,000 larvae, respectively. About 50% was normal healthy larvae among the spawned ones. Mouth sizes calculated by the angle mouth opening and upper jaw length for newly spawned red marbled rockfish larvae were 0.263, 0.197 and 0.132 mm at D, 0.75D and 0.5D, respectively, when the upper jaw length was 0.186mm. Thereafter, 20 days old larvae showed 0.822, 0.617 and 0.411 mm in calculated mouth length at D, 0.75D and rockfish larvae grows, their upper jaw length gradually increased. 2 days old red marbled rockfish larvae possibly stated to feed rotifers and lasted their feeding for the another 35days, relatively long periods compared with other larvae fish. And 25 days old larvae possibly fed the newly hatched Artemia nauplii and lasted their feeding for the another 20 days, like other larvae fish. The proper supplying time of artificial feeds for the red marbled rockfish larvae seemed to be around 10 days after spawning.

• 한국수산과학회지
• /
• 제49권2호
• /
• pp.146-153
• /
• 2016

A feeding experiment was conducted to determine the nutritional value of various dietary protein sources without a vitamin premix supplementation in juvenile black rockfish, Sebastes schlegeli. Diets containing similar quantities of lipid and carbohydrate with 50% crude protein from fish meal (FM)/soybean meal (SBM)/corn gluten meal (CGM), FM only, casein/gelatin, high FM/low casein and low FM/high casein were fed to rockfish along with a commercial rockfish diet. The diet containing only 65.6% FM and the commercial rockfish diet produced significantly greater weight gain (WG) and feed efficiency (FE) than all other semipurified diets (SPDs); the economical diet with 52.8% FM, 10% SBM and 5% CGM produced lower WG than the diet containing FM and commercial rockfish diet, but FE and survival were similar both diets. Intermediate responses were observed for rockfish fed the SPD containing 32.8% FM and 27.4% casein, while SPDs containing 10% FM and 41.8% casein and 38.5% casein and 10% gelatin yielded the lowest WG and FE. Some differences in tissue indices and body composition of rockfish were induced by the diets containing various protein sources and levels without the vitamin premix supplementation.

• Fisheries and Aquatic Sciences
• /
• 제17권2호
• /
• pp.229-247
• /
• 2014

Seven feeding trials were conducted to determine the effects of feeding rate and frequency in the Korean rockfish Sebastes schlegeli at seven different water temperatures. Two feeding-rate experiments for 5-g Korean rockfish at $17^{\circ}C$ and $20^{\circ}C$; three feeding rate experiments for 16-g Korean rockfish at $16^{\circ}C$ and $24^{\circ}C$; and finally, two feeding frequency experiments for 93- and 100-g at $15^{\circ}C$ and $20^{\circ}C$ were conducted. Twenty fish averaging $5.5{\pm}0.2$ g ($mean{\pm}SD$) were randomly distributed into 18 indoor tanks containing 40-L seawater from a semi-recirculation system. Fish were fed a commercial diet for 4 weeks at water temperatures of $17^{\circ}C$ and $20^{\circ}C$. Two feeding trials were conducted to determine the optimum feeding frequency in growing Korean rockfish reared at temperatures of $15^{\circ}C$ and $19^{\circ}C$. Broken line regression analysis of weight gain (WG) indicated that the optimum feeding rates of 5-g growing Korean rockfish were 4.48% (BW/day; BW, body weight) at $17^{\circ}C$ and 4.83% (BW/day) at $20^{\circ}C$. Broken line regression analysis of WG showed optimum feeding rates of 16-g juvenile Korean rockfish of 3.41% (BW/day) at $16^{\circ}C$, 3.75% (BW/day) at $20^{\circ}C$, and 3.34% (BW/day) at $24^{\circ}C$. The biological performance, results, along with morphological indices and serological characteristics, suggest that a feeding frequency of 1 meal/day was optimal to improve WG in growing Korean rockfish grown from 93 to 133 g at a water temperature of $15^{\circ}C$, and 100 to 132 g at $19^{\circ}C$.

• 수산경영론집
• /
• 제28권2호
• /
• pp.39-66
• /
• 1997

The objective of this study is to suggest the improvement method of the profitability in our marine fish culture business. So I investigated the actual condition for aquaculture farms in South Sea coast by the question and actual survey. 1 recognized the following facts; 1) The marine floating netcage system are a great portion in two province - Kyeongnam and Cheunnam, 2) The rockfish are reared absolutely much more than the olive flounder, 3) The polyculture by various species are more carried out than the monoculture of the olive flounder or rockfish, etc. I analyzed the profitability in olive flounder monoculture, rockfish monoculture, olive flounder and rockfish polyculture, and rockfish polyculture taking turns year by year respectively. At a result I comfirmed that the net income to net sales was the highest in the olive flounder monoculture bacouse the olive flounder,s sale price was higher than rockfish price. But internal rate of return(IRR) and net present value(NPV) were high in the olive flounder and rockfish polyculture or the rockfish taking turns polyculture. The reasons were alttributed to their high utility of a netcage and to reduction of a capital cost. So, I suggest 1) to feed the bigger product in short term, 2) to reduction of a feed and seed cost, 3) to increase a survival rate of fish and 4) to enlarge production by highly utilizing a netcage. And I recognized that a aquaculture manager should make constantly an effort to gain more profit by rearing more good products and by reducing a production cost.