• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.1
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• pp.13-17
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• 2004

The effects of temperature on nitrification of enriched nitrifiers were investigated by using kinetics and thermodynamics method through the batch test. Aquaculture recirculating water, which was sampled at Chung Cheong Buk-Do Inland Fisheries Research Institute, was analized to observe the characteristics of nitrification. Temporal variation of ammonium, nitrite and nitrate concentration was measured at batch experiments. Activation energy was calculated using Arrhenius equation with the oxidation rates of specific ammonium or nitrite ion. These oxidation rates were measured at temperature range of $6-35^{\circ}C$ and ammonium concentration range of 0.2-1.8 mg/L. Two distinct activation energy of Nitrosomonas sp. at temperature $6-15^{\circ}C\;and\;15-35^{\circ}C$ was 93.1 and 25.0 KJ/mol, respectively. Nitrate accumulation was observed at temperature over $15^{\circ}C.$

• Fisheries and Aquatic Sciences
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• v.26 no.12
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• pp.738-751
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• 2023

The Sembilan Archipelago is famous for its great biodiversity, in which the humphead wrasse (Cheilinus undulatus) (locally named Napoleon fish) is the primary commodity (economically important), and currently, the environmental degradation occurs due to anthropogenic activities. This study aimed to examine the eco-environmental parameters and assess their influence on the abundance of humphead wrasse and other coral reef fish compositions in the Sembilan Archipelago. Direct field monitoring was performed using a visual census throughout an approximately one km transect. Coral cover data collection and assessment were also carried out. A coastal water quality index (CWQI) was used to assess the water quality status. Furthermore, statistical-based analyses [hierarchical clustering, Pearson's correlation, principal component analysis (PCA), and canonical correspondence analysis (CCA)] were performed to examine the correlation between eco-environmental parameters. The Napoleon fish was only found at stations 1 and 2, with a density of about 3.8 Ind/ha, aligning with the dominant composition of the family Serranidae (covering more than 15% of the total community) and coinciding with the higher coral mortality and lower reef fish abundance. The coral reef conditions were generally ideal for supporting marine life, with a living coral percentage of about > 50% in all stations. Based on CWQI, the study area is categorized as good and excellent water quality. Of the 60 parameter values examined, the phytoplankton abundance, Napoleon fish, and temperature are highly correlated, with a correlation coefficient value greater than 0.7, and statistically significant (F < 0.05). Although the adaptation of reef fish to water quality parameters varies greatly, the most influential parameters in shaping their composition in the study area are living corals, nitrites, ammonia, larval abundance, and temperature.

• The Journal of Fisheries Business Administration
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• v.37 no.3 s.72
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• pp.1-24
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• 2006

In terms of the size of aquaculture farms and production volume, inland freshwater aquaculture is much smaller than marine aquaculture in Korea. However, freshwater aquaculture provides fish which is not produced in the sea. Freshwater aquaculture plays an important role in the efficient use of resources, development of local areas and economy vitalization in under - developed areas. freshwater aquaculture also helps ecosystem recovery by stocking farmed fry. As addressed above, inland freshwater aquaculture plays various roles and can not be ignored. However, freshwater aquaculture has been off the interest of fisheries authority. Considering a series of changes in the circumstances such as the government's disapproval of pen - raised aquaculture, higher standard for discharged water from aquaculture farms and a rapid increase in import of low price fish from other countries, it is difficult to expect the quantitative expansion of the freshwater aquaculture any more. Furthermore, freshwater aquaculture lost the trust of people because of the use of Malachite green, and the consumption of farmed product plummeted last year. Even though it would be difficult to expect the quantitative expansion, we could expect qualitative growth and let the inland freshwater aquaculture keep playing the own roles. In order to achieve competitive advantage and regain the trust by providing safer farmed product, the government's support and freshwater aquaculture industry's active and voluntary efforts are very important. This paper suggests several points for the future oriented inland freshwater aquaculture in Korea such as strategic intensive development of selected species, the technical improvement and its diffusion, increased cooperation among the government authority, industry and scientists.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.747-750
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• 2010

This study investigated the effect of wheat flour content in the diet on the growth of the snail Semisulcospira gottschei. Six diets were prepared containing wheat flour contents of 35, 40, 45, 50, 55, and 60%. Three replicate groups of snails (average weight 0.61 g) were fed each experimental diet for 8 weeks. The survival was above 85% in all groups, and did not differ significantly among treatments. The weight gain of snails fed the diets containing 35 and 40% wheat flour was significantly higher than that of snails fed the other diets (P<0.05), and the weight gain decreased when the dietary wheat flour content increased beyond 45%. The crude protein and ash contents in snails were significantly affected by the dietary wheat flour content (P<0.05). Therefore, a diet containing 35~40% wheat flour produces the optimal growth of snails. The results of this study will be used to develop cost-effective diets for commercial snail production.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.1
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• pp.1-7
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• 2018

We investigated patterns of antimicrobial resistance in Escherichia coli isolated from the water discharged from inland pollution sources in the Hansan-Geojeman and Jaranman-Saryangdo areas of Korea. A total of 217 strains of E. coli were isolated from 23 point-sources. These strains were tested for their susceptibility to 16 antimicrobial agents used in Korea for medical or veterinary therapy. The highest level of antibiotic resistance among the isolated strains was to tetracycline 10.6%, followed by ampicillin (3.2%), nalidixic acid (2.8%), rifampin (1.8%), trimethoprim (1.8%), trimethoprim/sulfamethoxazole (1.8%), chloramphenicol (1.4%), streptomycin (1.4%), cephalothin (0.5%) and gentamicin (0.5%). Resistance to at least one antimicrobial agent was present in 17.1% of the E. coli isolates. Only four of the isolated strains of E. coli showed multiple antibiotic resistance, which is defined as resistance to more than four antibiotics.

• Fisheries and Aquatic Sciences
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• v.24 no.11
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• pp.375-382
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• 2021

In this study, the reproductive behavior and embryonic and larval development of the short ninespine stickleback Pungitius kaibarae was described and illustrated based on observations during spawning, hatching, and larval rearing trials. Adult P. kaibarae were collected downstream in Jinhae during the reproductive season (April-May). Males had nuptial coloration on their entire black bodies, with blue dorsal spines and yellow eyes, whereas females had a brown spotted pattern on their bodies. Males built nests on the stems of water weeds and attracted females. Fertilization occurred in the nest immediately after spawning, and males guarded the eggs until hatching. The fertilized eggs of P. kaibarae were spherical, demersal, adhesive, and transparent, and each egg measured 1.43 ± 0.07 mm in diameter. The morula, blastula, and gastrula stages, as well as hatching began at 5, 18.5, 21.5, and 96 post fertilization (HPF), respectively, at 20.0 ± 0.5℃. The newly hatched larvae had a total length (TL) of 5.67 ± 0.50 mm, with a yolk volume of 0.583 ± 0.059 mm³. Their mouths and anuses had not yet opened. At 2 days posthatching (days post hatching, DPH), the yolk was completely absorbed and the larvae began to feed exogenously. Pigmentation was observed in freshly hatched larvae 4 h after hatching, with the presence of eight areas with a dotted pattern on the dorsal surface of the larvae and dispersed spots on the head and yolk sac. At 30 DPH, the TL of the juveniles was 21.34 ± 1.70 mm. The nest area and number of eggs were 259.56 ± 101.39 mm² (75.18-506.04) and 155.33 ± 114.12 (0-437), respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.505-513
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• 2022

In this study, 143 strains of Enterococcus spp. were isolated from inland pollution sources near shellfish farms on the west coast of South Korea. Not all isolated Enterococcus spp. strains possessed vancomycin resistance genes (VanA and VanB). However, since vancomycin-resistance Enterococcus (VRE) have been detected not only in the clinical field but also out in the world, it is possible that the VRE gene may be transferred to other bacterial strains commonly found in coastal waters where seafood is produced. It is important to monitor trends in the appearance of VRE. In addition, antimicrobial resistance patterns of isolates were examined in this study. Overall antimicrobial resistance rates were high: ciprofloxacin (32.2% of isolates resistant), chloramphenicol (30.8%), quinupristin/dalfopristin (19.6%), and tylosin (15.4%). Eight E. faecium strains (6.2%), out of the 129 strains assessed, showed multidrug resistance. All multidrug-resistant E. faecium showed resistance to erythromycin, quinupristin/dalfopristin, tetracycline, and tylosin, in all 14 strains. All multidrug-resistant E. faecalis showed resistance to erythromycin, quinupristin/dalfopristin, tetracycline, and tylosin. Both multidrug-resistant E. faecium and multidrug-resistant E. faecalis showed common resistance to erythromycin, quinupristin/dalfopristin, tetracycline, and tylosin.

• Korean Journal of Ichthyology
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• v.29 no.3
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• pp.176-189
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• 2017

Age estimation and sexual dimorphism of Coreoleuciscus splendidus were estimated using otolith, length-frequency distribution and 23 morphological measurements, from 245 individuals collected from September 2016, February and April 2017 in the Gapyeong stream, Han River, Korea. Result of age estimation of C. splendidus, we most examined were 2, 3 and 4-age, and the maximum observed ages were 5-age. Nine out of twenty-three morphometric measurements were significantly different between the genders. Anal fin have showing major sexual dimorphism in particular between adult individuals. This sexual dimorphism was based on extension of anal fin soft rays of male individuals. Therefore anal fin of males is always longer and wider than females. During spawning season male individuals possess nuptial tubercles on anal fin rays. However, another measurements and morphological characters does not exhibit sexual dimorphism in the between male and female individuals. The sexual dimorphism was observed to only over 2-years old individuals with sexual maturity. But juvenile and 1-years old individuals do not have sexual dimorphism with sexual maturity. Peak season of spawning was April to May and they start first spawning at 2-age. The ages at major spawning groups were most 3-age, and they maximum GSI index was 14.91 (female), 8.96 (male) at 5-age, respectively.

• Korean Journal of Ichthyology
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• v.22 no.4
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• pp.238-248
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• 2010

We performed field investigations at six stations in Buk Stream of Goseong-gun, Gangwon-do, Korea, from May to September 2009 to understand the stream's fish fauna and community structure. In the survey, 31 species belonging to 20 families were collected. Dominant species by number was Zacoo koreanus (30.0%), and subdominant species were Pungitius kaibarae (9.4%) and Rhynchocypris steindachneri (9.3%). In biomass, the dominant species was Tribolodon hakonensis (35.5%), and subdominant species were Z. koreanus (22.5%) and Cobitis pacifica (7.5%). Eight Korean endemic fish species and two endangered species (P. kaibarae and Pungitius sinensis) were collected. In addition, four anadromous fish species (T. hakonensis, Oncorhynchus masou masou, O. keta, Gasterosteus aculeatus) and two amphidromus fish species (Plecoglossus altivelis altivelis and Gymnogobius urotaenia) were observed. Interestingly, we verified the existence of several fish species in Buk Stream where they have not lived before. Those species were previously reported to live only in rivers that run into the western and southern sea of Korea. Five of those species (Zacoo koreanus, Z. platypus, Silurus microdorsalis, Liobagrus andersoni and Coreoperca herzi) were reported in Buk Stream in the 1980s. The other species (Pungtungia herzi, Pseudorasbora parva, Squalidus multimaculatus, Misgurnus mizolepis, Koreocobitis rotundicaudata, Silurus asotus and Odontobutis interrupta) have been introduced since the 1990s.

• Korean Journal of Ichthyology
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• v.32 no.4
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• pp.232-238
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• 2020

The objective of the present study was to investigate fish farm and growth performances of Chinese muddy loach (Misgurnus mizolepis) under indoor and outdoor aquaculture conditions for the domestic loach aquaculture industry. The investigation was conducted from August 2017 to October 2019 at one indoor farm (D-site) and two outdoor farms (P1-site and P2-site). Results showed that WG (weight gain), DWG (daily weight gain), and SWG (specific weight gain) based on growth measurements were 175.27±36.2%, 7.98±3.3%, and 0.94±0.2% at D-site, 320±34%, 4.07±0.6%, and 0.55±0.1% at P1-site, and 295.9±53%, 4.15±0.5%, and 0.62±0.1% at P2-site, respectively. WG was higher in outdoor farms (P1-site and P2-site), while DWG and SWG were higher in the indoor farm (D-site). Such differences of the present study might be due to differences in growth, water quality, plant and sale frequency depending on aquaculture types. In particular, outdoor farms takes more than a year to have sales whereas indoor farms can have sales three times in a year.