• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.1
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• pp.37-45
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• 2008

Assessment and management of fisheries abundance in fresh water like a river or a lake is very important to maintain fisheries itself as well as tourist industry even if their scale is not much large. The species for catch in fresh water are mainly a mandarin fish, a carp, an eel, and others. Because oriental river prawn is a main prey of these species and the change in its abundance is directly related to their abundance change in fresh water, information on the abundance and distribution of the species are necessary. Hydroacoustic survey is known to one of the efficient method among several methodology. Information on acoustic target strength is key parameter to estimate abundance for acoustic survey. In this study, measurements on oriental river prawn, Macrobrachium koreana, were conducted for two high frequencies(200kHz and 420kHz) with tilt angle using automatic rotating system. The results of acoustic target strength obtained from the experiment were compared with those of acoustic scattering model, Distorted Wave Born Approximation(DWBA) model. For 200kHz, the result of acoustic target strength experiments was expressed in terms of the averaged target strength dependence on the body langth(BL, cm) as a following relationship; < $TS_{200kHz}$ > = 45.9log(BL) - 107.4. These results provide basic information for studying acoustic target strength and conducting acoustic survey of oriental river prawn.

• Korean Journal of Environmental Biology
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• v.30 no.4
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• pp.314-318
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• 2012

The aims of the present study were to estimate the possibility for toxicity test and compare acute toxicity of potassium dichromate in the larva stage of Neocaridina denticulata, Daphnia magna and the juvenile stage of Oryzias latipes. N. denticulate, a freshwater shrimp lives in Korea, is an indigenous species and considered to be useful for toxicity test. D. magna and O. latipes were recommended as a test species for the OECD test guideline. The 96 h-$LC_{50}$ potassium dichromate value was 0.62 mg $L^{-1}$ for the larva stage of N. denticulata and 168.44 mg $L^{-1}$ for the juvenile stage of O. latipes. The 48 h-$EC_{50}$ value was 1.27 mg $L^{-1}$ for the D. magna. The study was confirmed higher sensitivity of the larva stage of N. denticulata to potassium dichromate compared to the D. magna and the juvenile stage of O. latipes.

• Journal of Marine Bioscience and Biotechnology
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• v.3 no.1
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• pp.1-6
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• 2008

Angola has a coastline of about 1,650 km long. Two diverging current namely, the Angola current with its warm water from the north and the cold Benguella Current in the south create a strong up-welling with a high productive ecosystem for marine resources. The area from Lobito to the mouth of the Cunene River, also known as the Southern fishing zone is by far the most productive of Angola's fishing zones. In 1977, the total potential of its marine fisheries sector was estimated at more than 700,000 tonnes per annum. In 2003, the Total Allowable Catch (TAC) established for demersal species was 57,600 tonnes and 160,000 tonnes for pelagic species. The most important resources are various marine demersal and pelagic fish including pilchard and the Cape and Cunene horse Mackerel (Tranchurus capensis and T. trecae). Sardinellas (Sardinella aurita and S. maderensis) are fished in parallel with horse mackerel. The rest of the catches are mainly demersal spp. and some deep water crustaceans. The demersal sppecies consist of Hake (Merluccius polli and M. capensis) and the large eye dentex spp. Tunas are caught at certain times of the year whilst some marine shrimp are also harvested from the Angolan waters. Angola also has several high value freshwater fish species, exploited by about 255 fishers. Tilapia sp. is among the most important and abundant fresh water fish found in Angola. Other species include the catfish (Clarias gariepinus) and fresh water prawns (Macrobrachuin rosenbergii). Some aquaculture ponds have been established in the country side, but due to lack of investment, proper training and the impact of civil war have seriously limited developments in the sub sector.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.230-239
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• 1997

In order to investigate the composition and the actual condition of extractive nitrogenous constituents in Tohajeot (a salted and fermented freshwater shrimp, Caridina denticulata denticulata) and in seasoned Tohajeot which were sold in the markets, the extract was analyzed separately into extractive nitrogen, free amino acids, oligopeptides, nucleotides and related compounds, quaternary ammonium bases, and guanidino compounds, using specimens collected at the fish markets of Yosu and Naju cities in 1994 and 1995. The salinity of Tohajeot was very high $(23.6{\sim}25.1)%$, but seasoned Tohajeot was relatively low $(8.4{\sim}11.4%)$. The extractive nitrogen in the extracts of Tohajeot and seasoned Tohajeot was $311{\sim}531\;mg\;and\;256{\sim}429\;mg$, and the total of free amino acids in them were $1,159{\sim}2,584\;mg\;and\;1,012{\sim}1,672\;mg$ respectively. Glutamic acid, leucine, lysine, histidine, alanine, ornithine, and tyrosine were the major amino acids in Tohajeot extract, and glutamic acid, lysine, arginine, aspartic acid, histidine, leucine and alanine were the main amino acids in seasoned Tohajeot. As for nucleotides and related compounds in them were $2.64{\sim}4.82\;{\mu}mol\;and\;1.08{\sim}1.93\;{\mu}mol$ respectively. Homarine, trigonelline, glycinebetaine and ${\beta}-alaninebetaine$ were detected in them. Homarine was the most abundant, ranging from 18 mg to 86 mg, but the others were very low. The content of major nitrogenous constituents in Tohajeot extract, such as extractive nitrogen, free amino acids, oligopeptides, nucleotides and related compounds, and betaines, was more abundant than that in seasoned Tohajeot extract. But the nitrogenous constituents of Tohajeot extract were poorer than those of anchovy sauce which was sold in the markets. Possibly, the extractive nitrogenous components, which consisted of total betains, total free amino acids, and phenylalanine might be recommended as the quality indices of standardizing Tohajeot and seasoned Tohajeot.

• Journal of the Korean Society of Food Culture
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• v.2 no.2
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• pp.149-161
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• 1987

The ways of preservation of chotkal which are classified by the principles of fermentation, are analyzed and interpreted. Chotkal is preserved mainly as two forms; one is chot and the other is shikhae. The fact that shikhae is preserved only in the eastern area can be attributed to two main reasons; (1) raw materials are available throughout four seasons and (2) relatively less production of salt. Chotkal is further classified into nine different ways of preservation and shikhae into fourteen. Regional characteristics for chot include that (1) in western part, Kechot is preserved in salty water (2) in central part Origuljot is fermented either with salt and powdered red pepper, or with salt, powdered red pepper and cooked cereal, (3) in southern part, freshwater shrimp with (1) salt only, (2) salt and powdered red pepper, (3) salt and cooked cereal, (4) salt, powdered red pepper and cooked cereal, (4) in northern part, fish with salt and powdered red pepper. Those for shikhae include that malt is used in southern part, shredded radish in northern part and cooked cereal more in southern part than in northern part.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.4
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• pp.380-389
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• 1994

Larvae of the freshwater shrimp, Macrobrachium nipponense(De Haan) were reared in the laboratory under constant conditions ($25^{\circ}C,\;7\%0$ S), and their feeding rate, oxygen consumption, ammonia nitrogen excretion, and growth were measured at regular intervals during development from hatching to post larval stage. Growth was measured as dry weight, carbon, nitrogen, hydrogen, protein and lipid. All these physiological and biochemical traits revealed significant changes from instar to instar. Average feeding rate was high in intermolt stage of the molt cycle and it showed a bell-shaped pattern. Respiration(R) increased from hatching to post larval stage. Excretion(U) increased in intermolt phase of larvae and it showed a bell-shaped variation pattern, in all larval instars with a maximum near the middle of the molt cycle. Regression equations describing rates of feeding, growth, respiration and ammonia excretion as functions of time during individual larval molt cycles were inserted in a simulation model, in order to analyse time-dependent patterns of variation as well as in bioenergetic efficiencies. Carbon was initially increased and nitrogen showed a tendency to increase in premolt phase during individual molt cycles. Protein remained clearly the predominant biochemical constituent in larval biomass.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.3
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• pp.237-246
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• 1995

Larvae of the freshwater shrimp, Macrobrachium nipponense were reared in the laboratory at constant condition $(25^{\circ}C,\;7\%o)$, and their feeding rate, oxygen consumption rate, and growth rate were measured in regular intervals of time during larval development. Regression equations describing rates of feeding, growth and respiration as functions of time during individual larval molt cycles were inserted in a simulation model in order to analyse time-dependent patterns of variation as well as in bioenergetic efficiencies. Absolute values for feeding, growth, respiration and assimilation showed clear changes during the molt cycle, The absolute and specific values of respiration (R: R/C) showed small variation during the individual molt cycles. Significance of respiration in relation to growth (G) increased within the carbon budget, respiration rate (R/C) outbalanced growth rate (G/C) in late premolt. When the portion of metabolizable carbon is respired (R/G), metabolic coefficient was < 1 (i.e. R$(K_2)$ decreased concurrently, In cumulative carbon budget, total feeding was $491.54\;{\mu}g$ C/ind., assimilation was $85.3\%$, respiration was $47.7\%$, and growth was $37.6\%$ from hatching to postlarval stage.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.447-451
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• 2020

For this study, we conducted a simultaneous multiresidue analysis of veterinary drugs in cultured fishery products in Chungnam Province in 2018. A total of 115 fishery product samples were obtained from fish farms and fishery production sites located in the province. In all, 29 residual veterinary drugs in the samples were analyzed using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. As a result, veterinary drug residues were only detected in a small number of the 106 samples (92.2%), and the detection rate was 7.8% (9 of 115 samples). The amounts were also below maximum residual limit (MRL) for fishery products, although one sample exceeded the MRL allowed by the Ministry of Food and Drug Safety and was detected in loach. The nine residual veterinary drugs were detected in 8 samples: loach, eel, catfish, freshwater bream, flatfish, rockfish and shrimp. The detected veterinary drugs were oxolinic acid, enrofloxacin, ciprofloxacin, sulfadiazine, flumequine and oxytetracycline. The most frequently detected antibiotic was oxolinic acid, and enrofloxacin exceeded the MRL in loach sample. Residues of most veterinary drugs were either not detected or were below the MRL, and while the status of fishery products is seen as safe overall, current surveillance efforts over veterinary drugs should be continued.