• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.588-593
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• 2001

Rockfish (Sebastes schlegeli) juveniles were fed with the diets containing 0 (control and sham), 5, 10 and 15 ppm of 3,5,3'-triiodo-L-thyronine ($T_3$) for 50 days to assess the effect of the hormone on the change of physiological condition, growth and survival rate, fish were fed the commercial diet by hand to satiation 2 times per day. After 50 days, food intake, feed efficiency, thyroid cell height (TCH), abnormality, proximate body composition, growth, condition factor and survival rate were also examined. The food intake and the feed efficiency of S. schlegeli fed with diet containing 10 ppm of $T_3$ was significantly higher than those of fishes fed with the other diets. On the final day of experiment, atrophy of thyroid gland was observed in fish administered with 10 and 15 ppm of $T_3$. $T_3$increased slightly the abnormality according to the increase of $T_3$dose. The whole body proximate analyses indicated that the fishes administrated with 15 ppm of $T_3$ were the highest in protein content and were the lowest in lipid, but in ash content were there a significant effects of $T_3$. The growth of S. schlegeli fed with a diet containing 10 ppm of $T_3$ was significantly higher than that of control. The condition factor was not related to administered $T_3$ content. $T_3$ slightly improved the survival rate of juvenile S. schlegeli, and the survival rate of fish administered with 10 ppm was significantly higher than that of sham-control but was lower than that of control.

• Korean Journal of Ecology and Environment
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• v.41 no.4
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• pp.547-553
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• 2008

In recent years, attention on the inhabitation environments of animals and plants which coexist with humans is growing more and more, and relevant research is being activated. In habitats of rivers, a lot of factors are interacting, even among them, some elements especially such hydraulic factors as water velocity and water depth, and such geological shapes as gravels, sand and mud are being considered as primary elements. In this study, various field investigations are carried out to determine the relationship between the river habitats of fishes and hydraulic primary elements using high-tech equipments. Furthermore numerical experiments to classify such habitats according to topographical spaces are carried out. In detail, hydraulic field investigations performed in this study can be summarized as topographical survey, discharge measurement, water level fluctuation monitoring and so on. In numerical experiments, the RMA2 model of the commercial program, Surface-Water Modeling System (SMS), which is widely used in conducting a two-dimensional analysis of the flow behavior of a river is utilized. In conclusion, as a result of field investigation, the relationship between water velocity and water depth is obtained. And the relationship between water velocity and water temperature is identified, too. Finally, using above obtained results, the inhabitation environment was classified into Riffle, Glide, Run, Pool, and E.D.Z according to the relationship between water velocity and water depth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.4
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• pp.507-528
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• 2015

The Fish Collection Project collected 356 fish species from the Southern Sea of Korea during 2010-2012, 55 more than previously collected. The fishes belonged to 3 classes, 29 orders and 128 families. The 5 dominant orders, Perciformes, Scorpaeniformes, Pleuronectiformes, Tetraodontiformes, and Clupeiformes, accounted for ~80% of the identified species. Additionally, 126 species were collected from the Southern Sea for the first time, while 85 species that had been found in previous collections were not seen. The species variety of fish in the Southern Sea may be influenced by its unique oceanographic conditions such as increased water temperatures in coastal areas, so regular surveys would assist our understanding of the fish community. We suggest that various collection methods, including diving, be used to collect fish species inhabiting rocky shore or deep-sea areas, where commercial fishing gear is difficult to deploy.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.6
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• pp.440-445
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• 2008

Ciprofloxacin is the most commonly used fluoroquinolones for treating bacterial disease in olive flounder (Paralichthys olivaceus) farming, but its withdrawal time for industrial-scale farming has not been established. The depletion of ciprofloxacin was investigated in the olive flounder under field conditions. Fish were kept in an inland fish farm and fed a commercial diet containing 5 mg/kg of ciprofloxacin for 13 days. Seven fishes per sampling time were examined during and after the treatment. Ciprofloxacin and its major metabolite, enrofloxacin, were analyzed using HPLC with a fluorescence detector. The concentrations of ciprofloxacin and enrofloxacin in muscle increased during the medication period, and then decreased rapidly. The ciprofloxacin and enrofloxacin concentration in the olive flounder peaked on days 11 and 13, respectively, with maximum concentrations in muscle of 0.58 and 0.73 mg/kg. Residual ciprofloxacin and enrofloxacin were eliminated rapidly; 6 days after treatment, the respective levels in muscle were 0.04 and 0.10 mg/kg and neither was detected 15 days post treatment. The level of ciprofloxacin accumulation at the beginning of oral administration was variable according to the farming conditions, but the overall exhaustion time was similar. In conclusion, an adequate withdrawal period for enrofloxacin is 15 days in the case of oral ciprofloxacin administration.

• Journal of the Korean Society of Food Culture
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• v.14 no.5
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• pp.555-563
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• 1999

This study was executed for 300 mothers bringing up a child below 3 years in the area of Kangnung to assess the current weaning practice of infants. 24.6% of mother surveyed were breast-fed, 57.8% were formula-fed and 17.5% were mixed-fed. The rate of breast feeding was lower and the rate of bottle feeding was higher in infants whose mothers had more income or higher educational period or full-time job. Most of the respondents knew the significance of supplementary food. 41.4% of the subjects started weaning of their infants at 3-4 months, and 84.1% of them set on weaning in less than 7 months after babies were born. And 39.4% of the subjects finished weaning of their infants in less than one year. The infants of this study preferred the fruits and fishes to meats, vegetables and beans that served to them as supplementary food. Mothers showed deep interest in recipe of weaning food(48.5%), adequate quantity of weaning food(36.3%), information on commercial food for infants(32.2%), and sequence in which semi-solid food are introduced(31.9%). From these results, it is suggested that education program in primary health center for improvement of weaning practice of infants should be implemented reflecting needs of mothers.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.16 no.1
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• pp.37-42
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• 1980

The purpose of the present study is to find the color induced maximum gathering rate and to observed'the trend of the - gathering rate by using two species of commercial fishes: rock bream, Oplegnathus fasciatus (Temminet et Schlegel) and 'grass puffer, Fugu niphobles (Jordan et Snyder). An experimental tank($360L{\times}50W{\times}55H cm$) was set up in a dark room. An illumination system was attached to the two end of tank to fix horizontal light intensity by co~bination c' one light bulb(20W) and four filters (red, blue, yellow, white) and the five regulating filters in order to fix light intensity. During the experiment water depth was maintained 50 cm lever in the tank. The tank was marked into six longitudinal sections each being 60 em long to observe the distribution of fish. The fish were acclimatized in dark condition for 40 minutes prior to the main experiment. Upon turning on the light, the number of fish in each section was counted 40 times every 30 seconds, and the gathering rates ,were obtain from the average number of fish in each secion. The color induced maximum gathering rate of rock bream appeared to be red, blue yellow and white color orderly.However, that of grass puffer appeared to be blue, white, yellow and red color orderly. Trend of the gathering rate in illumination time showed the remarkable fluctuation in the rock bream and little difference at the two color light sources. However, trend of the gathering rate in illumination time showed the little fluctuation in grass puffer and much difference at the two color light sources.

• Korean Journal of Ichthyology
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• v.21 no.2
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• pp.118-124
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• 2009

A Korean trawl fishery was conducted on the Emperor Seamounts in the northwestern Pacific Ocean from 2005 to 2007. Total catches were 750 mt, 460 mt and 440 mt in 2005, 2006 and 2007, respectively. Splendid alfonsino (Beryx splendens) and North Pacific armorhead (Pseudopentaceros wheeleri) were dominant in the commercial fisheries on the Emperor Seamounts during 2005-2007. Biomass of each species was estimated by the swept area method from March 2005 to August 2007. During three years, average biomass of Splendid alfonsino and North Pacific armorhead were 791 mt and 266 mt, respectively.

• Korean Journal of Ecology and Environment
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• v.54 no.3
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• pp.209-220
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• 2021

Pacific herring, Clupea pallasii, a keystone species with significant ecological and commercial importance, is declining globally throughout much of its range. While traditional fishing equipment methods remain limited, new sensitive and rapid detection methods should be developed to monitor fisheries resources. To monitor the presence and quantity of C. pallasii from environmental DNA (eDNA) extracted from seawater samples, a pair of primers and a TaqMan^® probe specific to this fish based on mitochondrial cytochrome b (COB) sequences were designed for the real-time PCR (qPCR) assay. The combination of our molecular markers showed high specificity in the qPCR assay, which affirmed the success of presenting a positive signal only in the C. pallasii specimens. The markers also showed a high sensitivity for detecting C. pallasii genomic DNA in the range of 1 pg~100 ng rxn^-1 and its DNA plasmid containing COB amplicon in the range of 1~100,000copies rxn^-1, which produced linear standard calibration curves (r²=0.99). We performed a qPCR assay for environmental water samples obtained from 29 sampling stations in the southeastern coastal regions of South Korea using molecular markers. The assay successfully detected the C. pallasii eDNA from 14 stations (48.2%), with the highest mean concentration in Jinhae Bay with a value of 76.09±18.39 pg L^-1 (246.20±58.58 copies L^-1). Our preliminary application of molecular monitoring of C. pallasii will provide essential information for efficient ecological control and management of this valuable fisheries resource.

• Korean Journal of Environmental Biology
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• v.34 no.3
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• pp.208-211
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• 2016

Essential oils (EOs) extracted from plants possess various biological activities and have been considered as natural insecticides due to their potent insecticidal activities. In regard to develop natural insecticides, EOs are formulated as an emulsifiable concentrate and their acute toxicity against to fishes were determined in a static condition using Cyprinus carpio. Coriander EO was used as an active ingredient mixed with ethanol for solvent and various surface active agents. The tested EOs were obtained from a commercial market, and three different extractions were also undertaken to produce EO using steam distillation, solvent extraction, and supercritical fluid extraction. Among the emulsifiable concentrate including a commercial coriander EO, surface active agents such as Tween 80, sodium dodecyl benzene sulfonate (SDBS), and mixture of SDBS and Nonidet showed acute toxicity to the fish. With the three different EO extraction, coriander EO obtained from supercritical fluids with Triton X-100 exhibited acute toxicity to C. carpio. Taken together, Tetgitol and Nondet are considered as surface active agents for the emulsifiable formulation of coriander EO.

• Korean Journal of Environmental Biology
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• v.27 no.3
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• pp.297-305
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• 2009

The Asian paddle crab, Charybdis japonica (A. Milne-Edwards) is an important fishery resource in Korea. Despite its common occurrence and commercial importance, few studies have been carried out on the life cycle and trophic ecology of these populations inhabiting on the tidal flat. Food habits of C. japonica populations were investigated on the Jangbong tidal flat, Incheon, Korea. Monthly samples were taken using a modified otter trawl from November 1999 to January 2001. Based on the examination of stomach contents from 257 individuals, the frequencies of occurrence and the relative volumes of food items were analysed. As a result, the crustaceans (the brachyura, the cirripedia and the harpacticoid copepoda), the echinoderms (the ophiuroidea) and the molluscs (the cephalopoda Loligo beka, the bivalves Bivalvia unid. and Mytilus galloprovincialis) were important food for this species. To examine ontogenetic shifts in diets, individuals of C. japonica were categorized into 2 different size classes (${\leq}60mm$ and ${\geq}61mm$ in carapace width) representing sexually premature and mature stages. The food items of the small crabs (${\leq}60mm$) were dominated by the crustaceans with the harpacticoid copepods constituting 84.6% of total prey number. The next group was the bivalves and the brachyurans. On the other hand, the large crabs (${\geq}61mm$) mainly feed on the bivalvia (Mytilus galloprovincialis and Bivalvia unid.), the brachyurans (Crab unid.) and occasionally the cephalopods and fishes. The difference in proportions of the main prey items among these two size classes was statistically significant. Therefore, the feeding habits of the portunid crab, C. japonica changed with growth.