East Sea Fisheries Research Institute
East Sea Fisheries Research Institute
Yamaguchi H.,Nagoya University |
Yamaguchi H.,Japan Aerospace Exploration Agency |
Kim H.-C.,Korea Polar Research Institute |
Son Y.B.,Korea Ocean Research and Development Institute |
And 4 more authors.
Progress in Oceanography | Year: 2012
Seasonal variability in satellite chlorophyll a concentrations (SCHL) in the Yellow Sea and the East China Sea (YECS) was investigated using 10-year averages of monthly data collected between September 1997 and October 2006. Interannual variations were also assessed to help clarify the influence of Changjiang River discharge (CRD) during summer. The YECS was represented by 12 areas each with different seasonal variability in SCHL. SCHL were overestimated during winter due to re-suspension of sediment near the Changjiang Bank and near coastal areas. Increases of SCHL were observed over large areas of the YECS during spring, as would be expected with the occurrence of spring blooms. The spatial distribution of the summer maximum of SCHL shifted from the Changjiang River mouth to just east of Jeju Island from July to September. An eastward shift of the high SCHL water coincided with the movement of the Changjiang diluted water (CDW), taking approximately 2. months to move from Changjiang River mouth to Jeju Island. Summer SCHL between 1998 and 2006 in this region were positively correlated with CRD with a time lag of 0-2. months, suggesting that the interannual variation of SCHL was controlled by the interannual variation of CRD. SCHL during summer in the Yellow Sea gradually increased over the 10. years, indicating possible eutrophication. © 2012 Elsevier Ltd.
PubMed | Kunsan National University, Inje University and East Sea Fisheries Research Institute
Type: Journal Article | Journal: Development & reproduction | Year: 2016
The ultrastructures of germ cells and the functions of Leydig cells and Sertoli cells during spermatogenesis inmale Kareius bicoloratus (Pleuronectidae) were investigated by electron microscope observation. Each of the well-developed Leydig cells during active maturation division and before spermiation contained an ovoid vesicular nucleus, a number of smooth endoplasmic reticula, well-developed tubular or vesicular mitochondrial cristae, and several lipid droplets in the cytoplasm. It is assumed that Leydig cells are typical steroidogenic cells showing cytological characteristics associated with male steroidogenesis. No cyclic structural changes in the Leydig cells were observed through the year. However, although no clear evidence of steroidogenesis or of any transfer of nutrients from the Sertoli cells to spermatogenic cells was observed, cyclic structural changes in the Sertoli cells were observed over the year. During the period of undischarged germ cell degeneration after spermiation, the Sertoli cells evidenced a lysosomal system associated with phagocytic function in the seminiferous lobules. In this study, the Sertoli cells function in phagocytosis and the resorption of products originating from degenerating spermatids and spermatozoa after spermiation. The spermatozoon lacks an acrosome, as have been shown in all teleost fish spermatozoa. The flagellum or sperm tail of this species evidences the typical 9+2 array of microtubules.
Kim J.-K.,Pukyong National University |
Bae S.E.,Pukyong National University |
Lee S.J.,Pukyong National University |
Lee S.J.,East Sea Fisheries Research Institute |
Yoon M.G.,Marine Biodiversity Institute of Korea
PLoS ONE | Year: 2017
Based on northern (NOL) and southern (SOL) mitochondrial lineages, recently, it proposed the new species Ammodytes heian and revived the species name Ammodytes japonicus to describe sand lances from the northwestern Pacific Ocean. This study used molecular methods to investigate genetic relationships between the two sand lance species in Korea and Japan. In total, 154 specimens were collected from four locations in Korea (Baengnyeongdo in the Yellow Sea, Tongyeong in the Korean Strait, and Jumunjin and Gijang in the East Sea), and 50 specimens were collected from a single location in Japan (Wakkanai in the Okhotsk Sea). Mitochondrial DNA analysis demonstrated that the individuals from Baengnyeongdo and Tongyeong all belonged to the SOL, whereas those from Gijang, Jumunjin, and Wakkanai included individuals from both the NOL and SOL (over 75% NOL). Population structure analyses were performed on the same individuals using seven microsatellite DNA markers. The population structure analysis based on 201 specimens identified two clusters (named as northern group and southern group), with the admixture proportion (q) of < 0.1 for the northern group in the Backyeongdo and Tongyeong sand lances and < 0.1 for the southern group in the Wakkanai sand lances. The high heterogeneity indicated that the former was probably A. japonicus and the latter probably A. heian. However, the admixture proportion in the Jumunjin and Gijang sand lances was 0.71-0.75 for the southern group, indicating that hybridization and unidirectional introgression from SOL to NOL occurs in southwestern margin of the East Sea. Our findings illustrate the speciation process based on different patterns of gene flow between Korean and Japanese sand lance, which is strongly influenced by both the paleo-climatic change and the contemporary local oceanic current pattern. © 2017 Kim et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Kim D.-H.,South Korean National Fisheries Research and Development Institute |
Lee K.-H.,South Korean National Fisheries Research and Development Institute |
Bae B.-S.,East Sea Fisheries Research Institute |
Park S.-W.,South Korean National Fisheries Research and Development Institute
Fisheries Science | Year: 2011
It is important to estimate the productive efficiencies of industries, especially the fishing industry, in order to determine policies that can improve business conditions. In this study, the productive efficiency of the sandfish coastal gillnet fishery on the east coast of Korea has been estimated using stochastic frontier analysis (SFA). A translog production function wherein the inefficiency was represented by a truncated-normal distribution was established; the output variable was the trip production quantity, the input variables were physical production factors directly related to the fishing activities of vessels, such as tonnage, horsepower, and the number of employed fishers. The average productive efficiency of the sample was 0.59 [0.40-0.79], which implied that productive inefficiency occurs in sandfish coastal gillnet vessels. Moreover, it was verified that there are no differences among the average productive efficiencies of fishing vessels of different tonnages. © 2010 The Japanese Society of Fisheries Science.
Park H.-H.,South Korean National Fisheries Research and Development Institute |
Millar R.B.,University of Auckland |
Bae B.-S.,East Sea Fisheries Research Institute |
An H.-C.,East Sea Fisheries Research Institute |
And 3 more authors.
Fisheries Research | Year: 2011
In 2008, Korean flounder (Glyptocephalus stelleri) was designated by the Korean Ministry for Food, Agriculture, Forestry and Fisheries as a species for restoration in the coastal waters of Korea. However, there are currently no regulations regarding the minimum landed size of flounder, or the minimum legal mesh size used by the coastal gillnet and trammel net fisheries. Selectivity experiments for gillnets and trammel nets were conducted using commercial vessels in several areas off the eastern coast of Korea between October 2006 and June 2009. The selectivity analysis required an adaption of the SELECT method because trammel net mesh sizes were altered part-way through the experiment. Gillnet and trammel net selectivity was best described using a bi-modal selection curve. The two gears were found to have different selection curves for a given mesh size. The length of maximum retention was similar for the two gears, but the selection curve of the trammel net was substantially wider than that of the gillnet. For the largest size of mesh used in the commercial fishery (8.5. cm stretched), 50% relative retention was estimated to occur at a length of 20.4. cm for the trammel net, and 22.5. cm for the gillnet. In comparison, the length of 50% maturity for this species is approximately 26. cm. As there are currently no size restrictions on landings of Korean flounder, these results suggest that use of these gears may pose a serious threat to local stocks of this species. © 2010 Elsevier B.V.
Lee K.,South Korean National Fisheries Research and Development Institute |
Bae B.-S.,East Sea Fisheries Research Institute |
Kim I.-O.,West Sea Fisheries Research Institute |
Yoon W.-D.,South Korean National Fisheries Research and Development Institute
Fisheries Science | Year: 2010
A species of giant jellyfish, Nemopilema nomurai, which has appeared only recently in the East China Sea, is an emerging nuisance in the northeastern region of Asia because of its extensive damage to fisheries. Until now, the biomass estimates of these jellyfish have mainly been obtained using trawl sampling and sighting survey methods. However, it is also necessary to determine the origin and diurnal migration patterns of these jellyfish. Drawbacks of the trawl sampling method are that it is effective only in estimating the density of jellyfish population distributed throughout the entire water column and requires considerable time. Another common analysis technique is the sighting method, which is effective only in the estimation of he density of jellyfish distributed in surface areas. The sighting method can determine distributions over wide areas in a short time. This method has limitations in investigating the vertical distribution and swimming behavior of jellyfishes. In our study, we utilized an echo sounding method extensively and effectively to overcome these limitations. Our method involved the use of a scientific echo sounder, acoustic camera, and conductivity-temperature-depth instrument during the drifting of a research vessel at various stations in the Yellow Sea. The acoustical method of particle tracking velocimetry (PTV) was used to analyze the swimming speed according to the vertical distribution of N. nomurai jellyfish. Results of the scientific echo sounder indicated that the jellyfish were mainly present in the water column from the surface up to a depth of 40 m. The mean swimming speed of the jellyfish was estimated as being 0.6 times the bell size (BS), with a tendency to maintain a certain speed. Further, results of a Monte Carlo simulation showed that the swimming speed was in the range of 0.46-0.89 BS. These results might be used as an index in a migration model, which may be useful to forecast the behavior and origin of the giant jellyfish entering inshore areas on a massive scale in northeastern Asia. © 2010 The Japanese Society of Fisheries Science.
Cho E.-S.,Korea Ocean Research and Development Institute |
Jeong H.-D.,East Sea Fisheries Research Institute
Journal of Environmental Biology | Year: 2012
The cDNA of Crassostrea gigas HSP70 was cloned and rapid amplification of cDNA (RACE) techniques were used. The full length of HSP70 cDNA was 2045 bp, consisting of a 5' terminal untranslated region (UTR) of 80 bp, a 3' terminal UTR 146 bp, and an open reading frame (ORF) of 1829 bp encoding deduced 620 amino acids. The HSP70 cDNA contained HSP70 family signatures, ATP-GTP binding site motif, tetrapeptide (GGMP) and conserved carboxyl terminal region (EEVD) at C-terminal of deduced amino acid sequence. BLAST analysis revealed that the HSP70 gene has an extreme similarity of 98.9% with C. gigas (AF144646). Northern blotting was used to examine the expression of HSP70 mRNA in the gill tissue of the oyster obtained from surface, middle and bottom layers. The HSP70 mRNA observed the samples taken from middle and bottom layers in September and February, but samples from the surface layer did not find a signal intensity of HSP70 mRNA transcript. Consequently, it seems that the oyster occurring middle and bottom layer have been stressed during the period of summer and winter, which is associated with the massive mortality in Gamak bay. © 2012 Triveni Enterprises.
Kang D.-Y.,West Sea Fisheries Research Institute |
Lee J.-H.,East Sea Fisheries Research Institute |
Kim W.-J.,West Sea Fisheries Research Institute |
Kim H.-C.,West Sea Fisheries Research Institute
Fisheries and Aquatic Science | Year: 2012
The starry flounder Platichthys stellatus, like all flatfish, exhibits conspicuous lateral asymmetry in numerous traits, most obvious of which is the migration of one eye to the other side of the head during metamorphosis. Additional changes related to eye migration include asymmetrical pigmentation, and a behavioral shift from larvae that exhibit upright, open-water swimming to juveniles and adults that lie on the ocean floor, eye side up. However, the morphology of these juveniles has been quite plastic in recent years, a phenomenon which is thought to be related to a diverse suite of semi-intensive and intensive larviculture methods. The cause of morphological abnormalities in the farmed flatfish is poorly understood. In the present study, we observe the features of morphological specificity and abnormality of immature fish (mean total length 23 cm) and survey the occurrence frequency of the specificity and abnormality of juvenile (mean total length 6.70 cm) in artificial culture facility. We find 2 types of abnormality (e.g., albino in ocular side and hypermelanosis in blind side) and 1 type of specificity (e.g., lateral polymorphism). These considerably differ from normal individuals (has sinistral eye and pigmented on only one side) by several characteristics (dextral eye, ocular side albinism, blind side hypermelanosis). The incidences of albinism, hypermelanosis, and body reversal are 10.1 ± 2.56%, 91.7 ± 1.7%, and 13.1 ± 1.1%, respectively. These suggest that these morphometric and morphological differences occur more in artificial environment during and just after metamorphosis. © The Korean Society of Fisheries and Aquatic Science.
Choi J.,East Sea Fisheries Research Institute |
Lee S.-M.,Gangneung - Wonju National University
Fisheries and Aquatic Science | Year: 2015
This study investigated the effects of dietary lipid sources on growth and fatty acid composition of juvenile Chinese longsnout catfish. Triplicate groups of fish (initial average weight, 3.8 g) were fed four diets containing either fish oil (FO), soybean oil (SO), linseed oil (LO) and lauric acid (LA) for 10 weeks. There were no differences among the groups in body weight, feed intake, feed efficiency, protein efficiency ratio, and body proximate composition of fish fed the diets containing different lipid sources (P > 0.05) during the study. However, fatty acids compositions of the whole body were influenced by dietary lipid source. Fish fed the SO diet had high concentration of linoleic acid, whereas those of fish fed the LO diet were rich in linolenic acid and arachidonic acid. Fish fed the FO diet had significantly (P < 0.05) higher levels of monounsaturated fatty acids such as 18:1n-9 and 20:1n-9 than those of fish fed the SO and LO diets. Eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) composition of body were not influenced by dietary lipid source. The results suggest that each of FO, SO, LO or LA can be used as a lipid source in the diets of Chinese longsnout catfish without any negative effects on growth and feed utilization and these data demonstrate the potential impact which dietary fat composition can change the body fatty acid profile. © 2015 The Korean Society of Fisheries and Aquatic Science.
Kim D.,Pusan National University |
Kang Y.H.,Catholic University of Daegu |
Lee J.B.,East Sea Fisheries Research Institute |
Ko G.R.,Pusan National University |
Jung I.H.,Pusan National University
Journal of Engineering Mathematics | Year: 2012
This paper is concerned with stabilization of an axially moving Kirchhoff string by boundary feedback control. We derive a nonlinear system describing transverse oscillation of the string using Hamilton's principle and prove exponential stabilization of the system by the direct Lyapunov method. The result shows that oscillation of a nonlinear axially moving Kirchhoff string can be suppressed by a new type of boundary feedback control. © 2012 Springer Science+Business Media B.V.