• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.2
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• pp.298-317
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• 2019

The physical characteristics of the Ulleung Warm Eddy (UWE) and its relationship with the East Korea Warm Current (EKWC) were analyzed using the CMEMS (Copernicus Marine Environment Monitoring Service) satellite altimetry data and the CTD data of the National Institute of Fisheries Science (NIFS) near the Ulleung Basin from 1993 to 2017. The distribution of the UWEs coupled with EKWC accounts for 81% of the total number of the UWEs. Only 7% of the total eddies are completely separated from the EKWC. The UWE has the characteristics of high temperature and high salinity water inside of it when it is formed from the EKWC. However, when the UWE is wintering, its internal structure changes greatly. In the winter, surface homogeneous layer of $10^{\circ}C$ and 34.2 psu inside of the UWE is produced by vertical convection from sea-surface cooling, and deepened to a maximum depth of approximately 250 m in early spring. In summer, the UWE changes into a structure with a stratified structure in the upper layer within a depth of 100 m and a homogeneous layer made in winter in the lower layer. 62 UWEs were produced for 25 years from 1993 to 2017. on average, 2.5 UWEs were formed annually, and the average life span was 259 days (approximately 8.6 months). The average size of the UWEs is 98 km in the east-west direction and 109 km in the north-south direction. The average size of UWE using satellite altimetric data is estimated to be 1~25 km smaller than that using water temperature cross-sectional data.

• Korean Journal of Ichthyology
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• v.28 no.2
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• pp.125-133
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• 2016

Sharks (Selachii) comprising about 510 valid species worldwide. Forty-three shark species belonging to 30 genera, 19 families and 8 orders have been found in Korean coastal waters, and all these are registered at the IUCN Red List as followings: endangered (EN) 1 species (2.3%) (vs. worldwide 15 spp., 3.2%), vulnerable (VU) 11 spp. (25.6%) (vs. 48 spp., 10.3%), near threatened (NT) 10 spp. (23.3%) (vs. 67 spp., 14.4%), least concern (LC) 9 spp. (20.9%) (vs. 115 spp., 24.7%), data deficient (DD) 12 spp. (27.9%) (vs. 209 spp., 44.9%), and critically endangered (CR) absent (vs. 11 spp., 2.4%). Twelve species among 43 sharks distributing in Korean waters are assessed as Threatened in the IUCN Red List categories and criteria as followings: Sphyrna lewini (EN, A2bd+4bd), Rhincodon typus (VU, A2bd+3d), Cetorhinus maximus (VU, A2ad+3d), Carcharodon carcharias (VU, A2cd+3cd), Isurus oxyrinchus (VU, A2abd+3bd+4abd), Alopias pelagicus (VU, A2d+4d), A. vulpinus (VU, A2bd+3bd+4bd), Carcharhinus plumbeus (VU, A2bd+4bd), S. zygaena (VU, A2bd+3bd+4bd), Squalus suckleyi (VU, A2bd+3bd+4bd), Squatina japonica (VU, A2d+4d), and S. nebulosa (VU, A2d+4d). Eighteen chondrichthyan species are registered in the list of the CITES Appendices, among them five sharks are distributing in Korean waters as Appendix II, i.e., R. typus, C. maximus, C. carcharias, S. lewini and S. zygaena. The scientific name of "Gobsangeo" has been changed from Squalus acanthias of the North Pacific to S. suckleyi, and "Mojorisangeo" from S. megalops of the Northwest Pacific to brevirostris.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.4
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• pp.292-302
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• 2012

This paper reviews comparison analysis of current and latest application for stock identification methods of Todarodes pacificus, and the pros and cons of each method and consideration of how to compensate for each other. Todarodes pacificus which migrates wide areas in western North Pacific is important fishery resource ecologically and commercially. Todarodes pacificus is also considered as 'biological indicator' of ocean environmental changes. And changes in its short and long term catch and distribution area occur along with environmental changes. For example, while the catch of pollack, a cold water fish, has dramatically decreased until today after the climate regime shift in 1987/1988, the catch of Todarodes pacificus has been dramatically increased. Regarding the decrease in pollack catch, overfishing and climate changes were considered as the main causes, but there has been no definite reason until today. One of the reasons why there is no definite answer is related with no proper analysis about ecological and environmental aspects based on stock identification. Subpopulation is a group sharing the same gene pool through sexual reproduction process within limited boundaries having similar ecological characteristics. Each individual with same stock might be affected by different environment in temporal and spatial during the process of spawning, recruitment and then reproduction. Thereby, accurate stock analysis about the species can play an efficient alternative to comply with effective resource management and rapid changes. Four main stock analysis were applied to Todarodes pacificus: Morphologic Method, Ecological Method, Tagging Method, Genetic Method. Ecological method is studies for analysis of differences in spawning grounds by analysing the individual ecological change, distribution, migration status, parasitic state of parasite, kinds of parasite and parasite infection rate etc. Currently the method has been studying lively can identify the group in the similar environment. However It is difficult to know to identify the same genetic group in each other. Tagging Method is direct method. It can analyse cohort's migration, distribution and location of spawning, but it is very difficult to recapture tagged squids and hard to tag juveniles. Genetic method, which is for useful fishery resource stock analysis has provided the basic information regarding resource management study. Genetic method for stock analysis is determined according to markers' sensitivity and need to select high multiform of genetic markers. For stock identification, isozyme multiform has been used for genetic markers. Recently there is increase in use of makers with high range variability among DNA sequencing like mitochondria, microsatellite. Even the current morphologic method, tagging method and ecological method played important rolls through finding Todarodes pacificus' life cycle, migration route and changes in spawning grounds, it is still difficult to analyze the stock of Todarodes pacificus as those are distributed in difference seas. Lately, by taking advantages of each stock analysis method, more complicated method is being applied. If based on such analysis and genetic method for improvement are played, there will be much advance in management system for the resource fluctuation of Todarodes pacificus.