• Parasites, Hosts and Diseases
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• v.57 no.2
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• pp.127-134
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• 2019

Sinuolinea capsularis Davis, 1917 is myxosporean that infect the urinary system of the host fish. Insufficient morphological and molecular data of S. capsularis exits, and it is therefore difficult to make an accurate identification of the parasite. We tried a series of morphological and molecular analysis to identify an myxosporean isolated from urinary bladder of cultured olive flounder, Paralichthys olivaceus, from Jeju island in the Republic of Korea. Some of them were observed under a light microscope and SEM, and remain samples were used molecular and phylogenetic analysis. Mature spores were subspherical, measuring $13.9{\pm}0.6{\mu}m$ in length and $13.8{\pm}0.8{\mu}m$ in width. Two spherical polar capsules on opposite sides in the middle of the spore had a diameter range of $4.3{\pm}0.4{\mu}m$. Scanning electron microscopy revealed that spores a severely twisted the suture line. By the morphological comparison and analysis, it was identified as S. capsularis. In addition, we obtained the partial 18S rDNA of S. capsularis and first registered it in NCBI. Phylogenetic analysis showed that S. capsularis clustered with Zschokkella subclade infecting the urinary system of marine fish, and it supported the infection site tropism effect on phylogeny of marine myxosporeans as well as the origin of Sinuolinea is not monophyly.

• Journal of Aquaculture
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• v.19 no.4
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• pp.225-230
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• 2006

A long-term (26 weeks) feeding experiment was conducted to examine the essentiality and requirement of inositol in diets for olive flounder because no information is available in the species. Five casein-gelatin based semi-purified diets were formulated to contain four different levels of myo-inositol (0, 0+antibiotic, 400, 800, and 1600 mg/kg, designated as M0, M0+, M400, M800, and M1600, respectively). One (M0+) of the control diets contained tetracycline hydrochloride (0.4%, wt/wt) as an antibiotic to inhibit biosynthesis of inositol by micro-organism in intestine of fish. Olive flounder at the early juvenile stage (initial body weight 1.22 g) were randomly distributed into fifteen 35 L tanks (48 fish/tank) and fed with one of the experimental diets (3 replicates per diet). At the end of the feeding trial, the weight gain, feed intake, specific growth rate, and protein efficiency ratio of fish fed diets containing higher levels of myo-inositol (M800 & M1600) were significantly higher than those of fish fed the other diets (P<0.05). Feed conversion ratio, survival, hematocrits, and hemoglobin of fish fed experimental diets were not significantly different among all the fish groups. Whole body compositions of fish were not different except for lipid content. The lipid content was significantly different between M0 and M400 diet groups. These results indicate that juvenile olive flounder requires dietary supplementation of myo-inositol in diets for normal growth and its optimum level seems to be approximately 800 mg myo-inositol/kg diet.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.753-760
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• 2013

Two feeding trials were conducted to investigate the effects of feeding rate and frequency on growth performance and body composition of juvenile Korean rockfish Sebastes schlegeli reared at $15.0{\pm}0.3^{\circ}C$. In the first trial, three replicate fish groups averaging $2.07{\pm}0.03g$ were fed a commercial diet with one of seven different daily feeding rates: 1.00%, 2.00%, 2.50%, 2.75%, 3.00%, 3.25%, and satiation (3.34%) based on body weight (BW). After four weeks of feeding, fish fed the 3% diet showed significantly higher weight gain (WG) and feed efficiency (FE) than fish that received the other feeding rates. In the second trial, the optimum feeding frequency was evaluated with three replicate fish groups averaging $2.04{\pm}0.03g$. Fish were fed a commercial diet at 2.87% BW with six different daily feeding frequencies: 2, 3, 4, 5, 7, or 9 meals. After four weeks of feeding, WG, specific growth rate, FE, and protein efficiency rate in fish fed 3 meals $d^{-1}$ were significantly higher than those of fish fed 7 or 9 meals $d^{-1}$. In both feeding trials, proximate composition of the entire body changed depending on the feeding rate or frequency. A broken-line regression analysis based on weight gain suggested that the optimum daily feeding rate and frequency for juvenile Korean rockfish at $15^{\circ}C$ was 2.9% BW $d^{-1}$ and 2-3 meals $d^{-1}$, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.1
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• pp.31-36
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• 1977

The monthly distribution of marine bacteria in the coastal waters of Chung-Mu was investigated from April, 1976 to March, 1977. The aim of this study was to obtain basic data for the prevention of food poisoning and for the efficient aquaculture of the area. Samples of sea water, mud, fish and shell fish were taken every month. The results are as follows: 1. One thousand four hundred and twenty-six strains were isolated from 732 samples of sea water, mud, fish and shell fish. They were 450 strains of Pseudomonas fluorescens, 422 strains of Achromobacter liquefacience, 72 strains of Vibrio parahaemolyticus, 234 strain of Vibrio alginolyticus, and 248 strains of Proteus vulgaris. 2. V. parahaemolyticus occupied $9.84\%$ of the total samples and $52\%$ of them were found in the sea water and mud. 3. The muds sampled districtly beneath the aquaculture raft contained much gas. They seemed to originate from the deposition of excretion of shell fish. The fatness of the shell fish was low where the gas was abundant. 4. It was .found that the shell fish with low fatness contained much Vibrio sp. 5. Regional distribution shows that marine bacteria were abundant in the order of station 10, 9, 8, 11, 1. The area around station 9 was polluted by reclamation of the area, and station 8 showed the influence of the excrement treat tank located nearly.

• Ocean and Polar Research
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• v.26 no.3
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• pp.415-423
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• 2004

An experiment was conducted to investigate the differences of total ammonia nitrogen (TAN) excretion rates and feces production rates among the offsprings from cultured Japanese strain (JJ, mean BW; $17.1{\pm}0.1g$), intraspecific hybrid strain between cultured Japanese and selected Korean strain (JK, mean BW: $17.1{\pm}0.1g$) and selected Korean strain(KK, mean BW: $21.5{\pm}0.1g$) of red sea bream in order to compare their dietary protein utilization efficiency. Fish were hand-fed with a commercial diet containing 46.7% crude protein for 2 weeks, three times daily 09:00, 13:00 and 17:00. After daily feeding, the TAN excretion rates reached peaks of 49.03, 58.75 and 36.26mg/kg fish/hr for the JJ, JK and KK strain, respectively, during the daytime. The value of the KK strain was significantly lower than that of the JJ and JX shuin (P<0.05), however daily TAN excretion rates of the JJ, JK and KK strain were not different (P>0.05). When fish were fed at satiation after 4 days of starvation, TAN excretion rates reached the maximum values 4 hours after the feeding fur the KK (31.23 mg/kg fish/hr) and 6 hours after the feeding fur the JJ (44.19 mg/tg fish/hr) and JK strain (41.70 mg/kg fish/hr). After 3 days of starvation, the daily endogenous TAU excretion rates (ETE) for the JJ, JK. and KK strain were 286.91, 215.66 and 179.29mg/kg fish/day, respectively. The value of the KK strain was lower than that of the JJ and JK strain (P<0.05). The total feces production rates of the JJ, JK and KK strain were not significantly different, however the proportions of feces production rates by time for the JJ, JK and KK strain were different (P<0.05). As overall results, efficiency of dietary protein utilization of JJ, JK and KK seems to be different and KK strain could offer a desirable option for aquaculture purpose.

• Journal of Life Science
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• v.18 no.6
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• pp.832-838
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• 2008

Mackerel water-soluble protein fraction produced by washing the mackerel meat were concentrated by isoelectric point shifting precipitation process, and the concentrates were utilized as the alternative feed of fish meal. In the 1st aquaculture diet experiment for Israel common carp, the feed conversion ratio decreased in proportion to the rise in the percentage of the recovered protein containing a residual lipid, which was added to the fish meal. It was supposed that the low feed efficiency was because of lipid oxidation in the recovered protein fraction. In addition, 2nd aquaculture diet experiment for Israel common carp was conducted after removing the oxidized lipid in the recovered protein fish meal. When a portion of the fish meal was substituted by the recovered protein devoid of the residual lipid, the feed conversion ratio increased in proportion to the amount of the substitute being added to the fish meal. Therefore, the recovered protein fraction of the mackerel washing wastewater from mackerel processing factory could be used as the alternative feed of fish meal.

• Korean Journal of Environmental Biology
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• v.40 no.1
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• pp.25-53
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• 2022

In this study, trends in research methods and topics of seabird and marine fish migration were examined. Based on the framework of existing animal migration studies, future research directions were proposed in relation to the migration of seabirds and fish. In terms of research methodology, with the development of science and technology, tracking techniques using radio telemetry, acoustic telemetry, RFID (radio-frequency identification), satellite tracking, and geolocators are widely used to study seabird and fish migration. Research is also conducted indirectly through a population survey and the analysis of substances in the body. Research contents are largely classified into extrinsic factors that affect migration(such as environmental variables and interspecific competition), intrinsic factors such as hormones, anthropogenic activities including fishery and offshore wind farm, and the effect of global climate change. In future studies, physiological factors that influence or cause migration and dispersal should be identified concerning intrinsic factors. For the analysis of migration ability, it is necessary to study effects of changes in the magnetic field on the migration ability of seabirds and fish, interspecific differences in spatiotemporal migration ability, and factors that influence the migration success rate. Regarding extrinsic factors, research studies on effects of anthropogenic disturbances such as fishery and offshore wind farm and global climate change on the migration and dispersal patterns of marine animals are needed. Finally, integrated studies on the migration of seabirds and fish directly or indirectly affecting each other in various ecological aspects are required.

• Development and Reproduction
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• v.20 no.3
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• pp.187-196
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• 2016

The objective of the current study was to determine acute plasma stress responses in two size groups of juvenile Epinephelus akaara (average body weight: $8.4{\pm}2.1$ and $3.3{\pm}0.6g$; 150 and 120 days after hatch, respectively) exposed to abrupt salinity drops (from 34 practical salinity unit, PSU seawater to 18, 10 PSU (experiment 1) or 26, 18, 10 PSU (experiment 2), respectively). Plasma glucose, glutamic oxalate transaminase, glutamic pyruvate transaminase, red blood cell counts, and gill histology were determined during 72 h exposure. Significantly increased plasma glucose, glutamic oxalate transaminase levels, and red blood cell counts were observed in fish exposed to 18 or 10 PSU. Histological changes, such as hyperplasia and lifting of epithelium in the gill secondary lamellae, were also observed in fish exposed to 18 or 10 PSU at 72 h post-drop. E. akaara exposed to sudden salinity drops to 18 or 10 PSU still seems to undergo the primary adjustment phase before fish reaches a new homeostasis, whereas fish exposed to 26 PSU seems to mount osmotic changes. Therefore, the no observed adverse effect levels for 72 h acute salinity challenge was 26 PSU in our study, and salinity drop to 18 PSU and below can possibly cause acute adverse effect, in which fish could be vulnerable to additional stresses such as a temperature changes or handling stress.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.1
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• pp.24-30
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• 2007

We developed an ecosystem indicator (EI) for the coastal and offshore areas of Korean waters. One of the major scientific challenges of this undertaking was to translate broad policy statements for ecosystem-based fisheries management (EBFM) into practical terms. Fish reproduction potential (FRP) was defined as an EI to describe the reproductive probability of adult fisheries resources in Korean waters. The FRP was estimated as the ratio of adult fish composition to total catch, catches (in metric tons) by species and by ecosystem, and fishery effort (in horse power per metric ton). The FRP indices of the East/japan Sea Ecosystem (EJSE), Yellow Sea Ecosystem (YSE), and East China Sea Ecosystem (ECSE) began to decrease after the mid-1980s, and the current indices have decreased further, at 0.63 (EJSE), 1.22 (YSE), and 0.68 (ECSE) index points compared to the indices of 1975, when similar catch amounts were recorded. Lower FRPs in the Korean marine ecosystems were the result of higher proportion of immature fisheries resources in the total catch. Because this kind of ecosystem-level indicator is thought to reflect scientific approaches to EBFM and to provide an important tool for assessing the current status of marine ecosystems with respect to both quantity and quality, more EIs should be developed for Korean waters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.309-314
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• 2001

In order to promote the consumption of small red muscle fish, such as saury, sardine, herring, etc., a new conditioning technique to soften backbone and small bones was investigated by using kimchi seasoning ingredients and organic acids. In the conditioning process, various chemical changes were examined during 60 days at 15 days intervals, The decrease of moisture content and the increase of salt concentration in seasoned fish meat were good correlated respectively. In the dry salt conditioning, the moisture content was more rapidly decreased than wet salt conditioning. The pH of fish meat during conditioning were more slowly decreased in dry salting than in wet salting. The VBN contents were suppressed under 30 mg/100 g in dry salt conditioning during 60 days at $5^{\circ}C$. The addition of rice bran in dry salting was effective on retarding lipid oxidation because the TBA value was most effectively retarded.