• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.1
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• pp.53-61
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• 2021

Distribution of fish community depends largely on environmental disturbance such as habitat change. In this study, we evaluated the impact of environmental variables and microhabitat patch types on fish distribution in Yudeung Stream at 15 sites between early May and late June 2019. We used non-metric multidimensional scaling to examine the distribution patterns of fish in each site. Gnathopogon strigatus, Squalidus gracilis majimae, Zacco koreanus, and Zacco platypus were associated with riffle and boulder areas, whereas Iksookimia koreensis, Acheilognathus koreensis, Coreoleuciscus splendidus, Sarcocheilichthys nigripinnis morii, and Odontobutis interrupta were associated with large shallow areas. In contrast, Cyprinus carpio, Carassius auratus, Lepomis macrochirus, and Micropterus salmoides were found at downstream sites associated with large pool areas, sandy/clay-bottomed areas, and vegetated areas. On the basis of these results, we suggest that microhabitat patch types are important in determining the diversity and abundance of fish communities, since a mosaic of different microhabitats supports diverse fish species. As such, microhabitat patches are key components of freshwater stream ecosystem heterogeneity, and a suitable patch composition in stream construction or restoration schemes will support ecologically healthy food webs.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.776-783
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• 2011

In a natural water body, a useful ecotechnology to reduce standing crops of phytoplankton is to strengthen the top-down force of zooplankton. However, the predation of fish for zooplankton can make the force weak. This study was conducted to find out the effect of fish on the grazing pressure of zooplankton in the mesocosms established in a eutrophic stream (Kyongan Stream) from October to November in 2010. In the corral with fish, chlorophyll a concentration increased, and a small size cladoceran Bosmina longirostris was dominant. In the corral without fish, chlorophyll a concentration decreased along with the domination of a large cladoceran Daphnia galeata and a large copepod Eudiaptomus japonicus. The size-selective predation of fish appeared to miniaturize the zooplankton community, to narrow their food-size spectrum, and to weaken the top-down force.

• Korean Journal of Veterinary Research
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• v.42 no.3
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• pp.289-297
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• 2002

The regional distribution and relative frequency of neurohormonal peptides-producing cells were demonstrated in the gut of the stomach teleost, the Mandarin fish, Siniperca scherzeri Steindachner, using 7 types of specific antisera raised against mammalian regulatory peptides. The gastrointestinal tract of the Mandarin fish was divided into three portions from proximal to distal, stomach, small intestine and large intestine. Cells showing immunoreactivities against regulatory peptides were situated in the epithelial lining, between epithelial cells, and gastric or intestinal gland regions with various frequencies along with gastrointestinal tract. Mast of immunoreactive cells in the epithelial lining portion were generally spherical or spindle shape having long cytoplasmic process that were reached to the lumen (open type cell) while cells showing round in shape (closed type cell) were found in the gastric gland of the stomach occasionally. Serctonin-, samatostatin-, gastrin-, cholecystokinin (CCK)-8- and human pancreatic polypeptide (HPP)-immunoreactive cells were observed in this study. However, no insulin- and glucagon-immunoreactive cells were found. Serotonin- and somatostatin-immunoreactive cells were restricted to the stomach regions with moderate and numerous frequencies, respectively. Gastrin-immunoreactive cells were demonstrated in the stomach and small intestinal portions with a few and moderate frequencies, respectively and CCK-8-immunoreactive cells were restricted to the small intestinal portions with moderate frequency. In addition, HPP-immunoreactive cells were demonstrated in the stomach and small intestine with numerous frequencies, respectively. In conclusion, the distribution and relative frequency of these immunoreactive cells in the gastrointestinal tract of the Mandarin fish shows peculiar patterns compared to those of other stomach and/or stomachless teleost.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.4
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• pp.248-262
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• 2005

The purpose of this study was to identify the state of demersal fish resource catch by small trawlers, which live in the southern waters off Goheung. We investigated the results of catch of sample fishing vessels, and performed fishing experiments using the actual fishing operation vessels from early November in 2002 till end of October in 2003. The daily amount of catch per vessel of the 35 small trawlers selected as sample vessels was the highest in summer seasons(June and July) as 70kg and the lowest in winter seasons(January and February) as 45kg and Octopus minor occupied as 17 to 30kg nearly 30% of the total catch. Additionally the catch of Octopus minor per vessel, per dragging hour ranges 3 to 6kg, which is the highest in March and June and the low in January to February, April to May and September. In the fishing experiments using small trawler, during the study period, a total of 75 fish species were collected. The number of individuals by species consisted 58.2% in Shrimps, 17.8% in Fish, 2.3% in Cephalopod. Of these, Parapenaeopsis tenella was the highest in 29.2%, Squilla oratoria and Crangon hakodatel was 14.6% respectively and Octopus minor was 0.2% of the total number of individuals. As far as the appearance number of individuals by month was concerned, February was the highest and then May, April and June followed in order, and October showed the lowest. Additionally the monthly catch per dragging was the lowest in December to January as 20kg and the highest in July as 160kg. Specially, Octopus minor was caught throughout the year regardless of season and the catch was the highest at the period from March to June. When looking into the body mean length of dominant fishes caught, we could observe the followings; Trachurus japonicus 8.9cm, Cynoglossus robustus 10.8cm, Muraenesox cinereus 15.3cm, Setipinna taty 10.3cm, Amblchaeturichfhys hexanema 9.3 cm and Collichthys niveatus 8.9cm, most of which were in their immaturity when they were caught.

• Spatial Information Research
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• v.6 no.1
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• pp.91-102
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• 1998

The objectives of this research were to develop fish-habitat relationship models which can be used to estimate fish species riclmess of small and medium rivers in Korea, and test the accuracy of the models. The models are based on the Aquatic GAP Analysis model in the New York Cooperative Fish & Wildlife Research Unit (19%), and they employ three habitat factors; river size, physical habitat, and water quality of each river segment. Model 1 and model II are based on the water quality standard for life support of EP A and the water quality class of Korea, respectively. Test sites for this study include one urban stream and three less spoiled tributaries of the Han River. The results of this research can be summarized as follows. First, the number of habitat types identified by model I and model II are nine and 14, respectively. Second, the average accuracy of the three distribution maps of rare or endangered fish species are 80.6% (model 1) and 81.2% (model II). Third, the accuracy of fish species richness are 94% (model 1) and 95% (model II), and the water quality is the most important factor affecting fish species richness. Fourth, the accuracy of fish species list are 50.5% (model 1) and 68.7% (model II), but the accuracy of less spoiled stream segments and that of polluted stream segments are 67.1% and 86.5%, respectively. Finally, it can be concluded that the overall performance of model II is better than that of model I at our test sites.

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.270-277
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• 2023

Since its introduction in 1973, the bass, Micropterus salmoides, has spread to dams and rivers in Korea, adversely affecting native fish communities. In this study, after complete removal of bass from Bukchosan Reservoir, an farm reservoir that has lost its function, an attempt was made to indirectly confirm the adverse effects of bass on fish by comparing fish communities in reservoirs of a similar size where bass inhabit. The study was conducted three times a year from 2019 to 2022. As a result of the study, in Bukchosan Reservoir, where the species composition of fish was judged to be simplified due to the habitat of bass, only four species such as Carassius auratus and Rhinogobius brunneus that could be used as a food source for bass appeared before the removal of bass, but after the removal of bass. The appearance and increase of the population of the introduced small freshwater fish (Oryzias sinensis, Rhinogobius giurinus) were confirmed. When comparing Gangjeong Reservoir, Susim Reservoir, which are other reservoirs inhabited by bass investigated in this study, and Bukchosan Reservoir, this result is judged to show a trend of stabilization and recovery of fish species after removal of bass in small reservoirs with high predation pressure of bass.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.614-623
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• 2015

This study aims to estimate the Green-House-Gas emissions from domestic farmed flounder in the southern sea and Jeju-Do, where is mainly produced, by the assessment of energy consumptions and GHG emissions from domestic fish farms for establishing reduce standards of greenhouse gas from a sustainable perspective. It needs to analyze such GHG emission components as feed, electricity, fuel, fixed capital, fish respiration, and liquid oxygen in two locations by 4 stage running water type farm size of small, small and medium, large and medium, large scale. The result showed that the mean GHG emissions were $36.83kg{\cdot}CO_2/year$ in the southern sea and $24.33kg{\cdot}CO_2/year$ in Jeju-Do, respectively, in the stage of production per fish 1kg at 2 locations and farm size from domestic farmed flounders, and it will give to be useful for policy, planning, and regulation of aquaculture development with establishing GHG reduction standards.

• Korean Journal of Environmental Biology
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• v.24 no.1 s.61
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• pp.29-37
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• 2006

We investigated the feeding habits of Rhynchocypris kumgangensis in Hongcheon River of Saenggokri, Seoseokmyeon, Hongcheongun, Gangwon-do, Korea from April 2002 to March 2003. The fish is korean endemic species upper streams in Korea. It was asscertained that R. kumgangensis is a carnivore and consumes mainly Ephemeroptera, Diptera, Terrestrial insects and Trichoptera. The most important prey was chironomids: Chironomus sp. Their feeding habits changed according to growth. Small fish fed mainly on small prey organisms such as Diptera, while larger fish fed much more on Ephemeroptera and Terrestrial insects. There were also seasonal changes in the relative proportion of their food items.

• Applied Microscopy
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• v.46 no.2
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• pp.93-99
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• 2016

The thickness of specimen is an important factor in microscopic researches. Thicker specimen contains more information, but it is difficult to obtain well focused image with precise details due to optical limit of conventional microscope. Recently, a microscope unit that combines improved illumination system, which allows real time three-dimensional (3D) image and automatic z-stack merging software. In this research, we evaluated the usefulness of this unit in observing thick samples; Golgi stained nervous tissue and ground prepared bone, tooth, and non-transparent small sample; zebra fish teeth. Well focused image in thick samples was obtained by processing z-stack images with Panfocal software. A clear feature of neuronal dendrite branching pattern could be taken. 3D features were clearly observed by oblique illumination. Furthermore, 3D array and shape of zebra fish teeth was clearly distinguished. A novel combination of two channel oblique illumination and z-stack imaging process increased depth of field and optimized contrast, which has a potential to be further applied in the field of neuroscience, hard tissue biology, and analysis of small organic structures such as ear ossicles and zebra fish teeth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.1
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• pp.35-41
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• 2006

The feeding habits of Spanish mackerel (Scomberomorus niphonius) were studied based on the examination of stomach contents of 445 specimens collected from January to December 2004, in the Southern Sea of Korea. The size of Spanish mackerel ranged from 26.1 to 105.4 cm in fork length (FL). Spanish mackerel was a piscivorous fish which mainly consumed teleost fishes such as chub mackerel (Scomber japonicus) and anchovy (Engraulis japonicus). Its diet also included small quantities of shrimps, stomatopods, cephalopods, crabs, polychaetes, amphipods, cumaceans and copepods. Smaller individuals (<60 cm FL) consumed small fishes such as Engraulis japonicus and crustaceans. The portion of these prey items decreased with increasing fish size, and this decrease was paralleled with increased consumption of lager fishes such as Scomber japonicus and Cololabis saira. The prey size increased with the increase of fish size.