Aidanosagitta crassa, a key species in South Korea’s coastal waters, exhibits three morphological types: Type C with a collarette-containing trunk, Type N lacking a collarette, and an intermediate Type I. Limited research studies have been conducted on their ecological patterns, prompting this study to elucidate seasonal occurrence patterns of A. crassa types in Pyeongtaek. Field surveys at six stations in Pyeongtaek port were conducted in winter (Feb.), spring (May), summer (Aug.), and autumn (Nov.) of 2010. Water temperature and salinity were measured and zooplankton samples were collected for abundance analysis. Type C predominated in winter and autumn. Type I predominated in summer and Type N predominated in summer and autumn. Occurrence patterns were influenced by water temperature. Type C showed a negative correlation with water temperature. Type N was positively correlated with water temperature. However, Type I showed no significant correlation with water temperature. In 2013, genetic sampling using the mtCOI marker was conducted in winter and summer. Despite morphological differences, genetic analysis revealed intraspecific diversity due to seasonal environmental changes.

To analyse and review the fishing performance and species composition according to the size of the entrance and mesh of the pot in the southern coastal waters (Tongyeong, Gyeongsangnam-do and Yeosu, Jeollanam-do), the experiment in this study caught one class, eight orders, 17 families, 23 species, 662 fishes, and 99,833 g. The largest number of fish species was Conger myriaster (301 fishes caught) accounting for 45.5%, followed by Octopus vulgaris (152) accounting for 23.0%, Charybdis japonica (45) accounting for 6.8%, Sebastiscus marmoratus (43) accounting for 6.5%, and Parapercis sexfasciata (42) accounting for 6.3%. Conger myriaster, Octopus vulgaris, Charybdis japonica, Sebastiscus marmoratus, and Parapercis sexfasciata accounted for 88.1% of the total catch. For other fish species, 68 fishes of 18 species were caught, accounting for 12.5% of the total. As a result of the total catch survey, the catch rate of Conger myriaster was the highest at 50.9% in B. 22 mm/280 mm. In addition, the average total length per fish increased as the entrance size increased. The weight ratios of Conger myriaster, Octopus vulgaris, and other fish species based on the total weight caught in each pots of the six species of test fishing gear are as follows. A pots 66.6%, 26.5%, 6.9%, B pots 57.2%, 24.5 %, 18.3%, C pots 43.2%, 31.5%, 25.3%, D pots 7.4%, 56.7%, 35.9%, E pots 43.6%, 0%, 56.4%, and F pots 5.0%, 79.6%, 15.4%.

이 연구는 한·중·일이 각각 선포한 배타적 경제수역이 중첩되는 수역의 법적 성격과 연안국 및 기국의 권리와 의무를 분석한다. Ⅱ장에서는 한·중·일의 배타 적 경제수역의 선포와 연안국 간 잠정어업협정 체결로 형성된 법적 사실관계를 정리하고, 해당 수역을 배타적 경제수역(EEZ), 잠정적 공동관리 구역 (provisional joint regulation zones), 유보 수역(reserved waters)으로 분류하여, 분쟁수역이 배타적 경제수역과 공해의 이중적 성격을 갖는다는 결론의 전 제를 도출한다. Ⅲ장에서는 분쟁수역이 배타적 경제수역 또는 공해로서의 이중적 법적 성격 을 갖는 근거를 제시하고, 분쟁수역에 대한 배타적 경제수역과 공해의 법리 적 용 논거를 통해 연안국 및 기국의 권리와 의무를 쟁점 사안별로 검토한다. 특 히, 공해의 법리가 적용되는 논거에서는 UN해양법협약상 배타적 경제수역의 공해적 특성과 분쟁수역의 특성에 따른 공해의 법적 성격을 구분하여 살펴본 다. 해당 수역의 잠재적 법적 성격을 분석함으로써 동북아시아 내의 분쟁수역 에 대한 구체적 이해에 기여한다.

The issue of marine accidents can be based on the traffic/distribution of vessels in the waterways. These accidents are often associated with human and financial losses and require special attention. Usually, these accidents include collision of two fishing vessels with each other, collision of a fishing vessel with other types of vessels in the course and collision of a fishing vessel with an obstacle in the course (Yancai, et al, 2020). In this article, we first want to deal with analysing the recorded statistical samples in 7 fishing areas in coastal waters of South Korea in 2023, while fuzzy clustering them. Then, according to analysing the sample data and finding the probabilistic structure and the membership of data sets the determined clusters, through Monte Carlo simulation, we will generate similar data in each of the 7 studied regions and model them in unsupervised mode. The generated data by Monte Carlo simulation based on the statistical distribution will able us to study the reality of distribution and possible accident in our target areas and find the model for future demands. We show that how the simulated data reduce the cost of data analysis and deliver us the facts of clusters for fishing vessels collisions. Finally, we reach to the most notified area for preventing the fishing vessels accidents and to make more preparations for reducing the human and costly damages in future activities.

A variation of fish assemblage in the coastal waters of Sagye-ri, southern Jeju Island was determined using samples collected by trammel net from 2012 to 2022. The total fish species caught by trammel net were identified 88 species, 46 families, 12 orders, and the number of appearance and biomass were 3,479 individuals and 883.6 kg. The annual variation of species was the highest in 2013 at 46 species and the lowest in 2021 at 30 species. The seasonal variation of species was higher in summer at 67 species and lower in winter, autumn at 47 species. The annual diversity index, evenness index, and richness index were appeared 2.42-3.00, 0.69-0.78 and 5.18-7.24 at each years. The dominance index appeared highest in 2013 and the lowest in 2018. Cluster analysis based on the number of individuals of fish was classified into two groups at the dissimilarity level of 57%, and results of SIMPROF analysis revealed significant differences in community structure among the two groups. The subtropical fishes were identified a total of 42 species (47.7%) and the number of species was higher in 2013 at 25 (54.3%) species and lower in 2018 and 2021 at each 17 (54.8~56.7%) species. The dominant species of subtropical fishes were appeared rabbit fish (Siganus fuscescens), scarbreast tuskfish (Choerodon azurio), bluestriped angelfish (Chaetodontoplus septentrionalis), balloon fish (Diodon holocanthus), and flag fish (Goniistius zonatus) at study sites.

본 연구는 8월에 한반도를 우회하며 동해상으로 빠져나간 2018년 제 19호 태풍 Soulik과 서해상으로 북진하여 통과한 2020년 제 8호 태풍 Bavi을 통해 태풍 유입 전‧후에 따른 한반도 해역별 수온 변동성을 분석하였다. 분석자료는 국립수산과학원 실시간 수온 자료와 수온관측소 근처 AWS의 바람자료 및 NOAA/AVHRR 위성 수온자료를 활용하였다. 분석 결과 이동경로가 다른 태풍이 한반도를 통과할때 동해에서는 풍속과 풍향에 따라 수온의 상승(북풍)과 하강(남풍)이 반복적으로 발생하였는데 특히 태풍 Soulik 유입 시 10 ℃ 안팎의 급격 한 수온 하강을 보였다. 서해는 태풍 Bavi의 중심부가 통과되면서 서해 일부 해역에서 수온이 상승되었고, 차가운 물덩어리가 존재했던 남 해 일부 해역에서도 태풍 Bavi의 이동으로 따뜻한 수온이 유입되어 평년 수온으로 회복된 것으로 나타났다. 또한 태풍 유입시 서해와 남해 는 지형적‧환경적 조건으로 인해 각 해역별 특성에 맞게 수온 변동이 다르게 나타났다. 본 연구를 통해 태풍으로 인한 한반도 해역별 수 온 변동을 해석함으로써 이상기후에 따른 양식 생물의 부정적인 영향을 최소화하고 해역별 수산재해의 피해대응 전략을 수립하는데 기여 할 것으로 사료된다.

Long term variations of fish assemblage in the coastal waters of Bukchon-ri were determined using samples collected by trammel net from 2012 to 2022. Water temperature increased by 0.4℃ in 2022 that was less then 2012. During the survey period, a total of 95 species (53 families and 15 orders) of fishes were identified, Scorpaeniformes (five families and 22 species) and Perciformes (25 families and 39 species) accounted for 73% of the total number. The number of species was higher in summer than winter, showing a peak in summer at 66 species and lower in winter and autumn at 45 species. The number of individuals and the biomass peaked in summer at 1,238 individuals and 280.1 kg, and were the lowest in autumn at 597 individuals and 155.4 kg. The annual diversity index, evenness index and richness index were appeared 2.11-2.80, 0.64-0.80 and 4.70-7.34 at each years. The dominance index were appeared highest in 2014 while 2021 were appeared the lowest in 2017. The subtropical fishes were identified total of 38 species (40.0%) and the number of species was higher in 2022 at 22 (52.4%) species and lower in 2015-2017 at each 10 (31.3-37.0%) species. The dominant species of subtropical fishes were appeared rabbit fish (Siganus fuscescens), boxfish (Ostracion immaculatus), smallscale blackfish (Girella melanichthys), flag fish (Goniistius zonatus), stripey (Microcanthus strigatus), rock porgy (Oplegnathus punctatus), and bluestriped angelfish (Chaetodontoplus septentrionalis) in study sites.

In this study, changes in the microbial ecosystem of the Yeongheungdo island coastal waters were investigated for five years to collect basic data. To evaluate the influence of distance from the coast on the microbial ecosystem, four sites, coastal Site (S1) and 0.75, 1.5, and 3 km away from the coast, were set up and the changes in physicochemical and biological factors were monitored. The results showed seasonal changes in water temperature, dissolved oxygen, salinity, and pH but with no significant differences between sites. For nutrients, the concentration of dissolved inorganic nitrogen increased from 6.4 μM in April-June to 16.4 μM in July-November, while that of phosphorus and silicon phosphate increased from 0.4 μM and 2.5 μM in April-June to 1.1 μM and 12.0 μM in July-November, respectively. Notably, phosphorus phosphate concentrations were lower in 2014-2015 (up to 0.2 μM) compared to 2016-2018 (up to 2.2 μM), indicating phosphorus limitation during this period. However, there were no differences in nutrients with distance from the coast, indicating that there was no effect of distance on nutrients. Phytoplankton (average 511 cells mL-1) showed relatively high biomass (up to 3,370 cells mL-1) in 2014-2015 when phosphorus phosphate was limited. Notably, at that time, the concentration of dissolved organic carbon was not high, with concentrations ranging from 1.1-2.3 mg L-1. However, no significant differences in biological factors were observed between the sites. Although this study revealed that there was no disturbance of the ecosystem, further research and more basic data on the microecosystem are necessary to understand the ecosystem of the Incheon.

Establishing a ship's passage plan is an essential step before it starts to sail. The research related to the automatic generation of ship passage plans is attracting attention because of the development of maritime autonomous surface ships. In coastal water navigation, the land, islands, and navigation rules need to be considered. From the path planning algorithm's perspective, a ship's passage planning is a global path-planning problem. Because conventional global path-planning methods such as Dijkstra and A* are time-consuming owing to the processes such as environmental modeling, it is difficult to modify a ship's passage plan during a voyage. Therefore, the D* algorithm was used to address these problems. The starting point was near Busan New Port, and the destination was Ulsan Port. The navigable area was designated based on a combination of the ship trajectory data and grid in the target area. The initial path plan generated using the D* algorithm was analyzed with 33 waypoints and a total distance of 113.946 km. The final path plan was simplified using the Douglas–Peucker algorithm. It was analyzed with a total distance of 110.156 km and 10 waypoints. This is approximately 3.05% less than the total distance of the initial passage plan of the ship. This study demonstrated the feasibility of automatically generating a path plan in coastal navigation for maritime autonomous surface ships using the D* algorithm. Using the shortest distance–based path planning algorithm, the ship's fuel consumption and sailing time can be minimized.

Fish samples were collected by a set net from April to December 2020 at the coastal waters off Tongyeong, Korea to determine fish species composition and seasonal variation. A total of 330,675 fish (1,032,578 g) representing 56 species belonging to 39 families were collected during the sampling period. The dominant species were Engraulis japonicus, Trachurus japonicus and Trichiurus japonicus, which accounted for 98.1% of the total number of individuals and 87.5% of the total biomass collected. E. japonicus and Chelidonichthys spinosus appeared every month off the coast of the Tongyeong. Cluster analysis based on the number of individuals of fish were classified into two groups at the dissimilarity level of 57%, and the results of ANOSIM analysis revealed significant differences in community structure among the two groups

The purpose of this study is to provide information about annual variations in catch size and changes in reproductive biology in the common octopus, Octopus vulgaris, a commercially important species in Jeju Island. Samples were collected from coastal waters of Jeju Island, Korea by coastal trap fishery from January to November 2021. Octopus vulgaris have been decreasing in this region since 1984. The mantle length (ML) ranged from 4.5 to 17.8 cm and body weight (BW) ranged form 88.5 to 2,657.5 g. A χ 2 -test revealed that the number of males was significantly greater than females (χ 2 = 32.712, df = 10, P<0.05). Mature females were found from January to July and male occurred January to August. The gonadosomatic index value was higher from July to August than other months. The relationship between mantle length and body weight was BW = 2.4527ML 2.3139 (female) and BW = 2.6785ML 2.3159 (male). At 50% group maturity, female and male average weight was estimated to be 554.7 g and 330.6 g, respectively.

Unarmored and thin-walled dinoflagellates were collected from brackish and coastal waters of Korea from August 2019 to August 2021. A total of 10 species belonging to orders Sussiales and Gymnodiniales were isolated and established as clonal cultures. Of them, five species (Biecheleria brevisulcata, Lepidodinium chlorophorum, Karlodinium decipiens, Kirithra asteri, and Wangodinium sinense) are newly recorded in Korea and examined using a light microscope (LM) and a scanning electron microscope (SEM). Their molecular phylogeny was inferred from LSU rDNA sequences. Here, we present taxonomic information, morphological features, and molecular phylogenetic positions of these unrecorded dinoflagellate species.

In this study, the vertical distribution of giant jellyfish analyzed echo counting method and such survey methods as sighting and trawl were used to compare its density estimates. In May and July 2021, surveys were conducted in the East China Sea and the coastal waters of Korea. As a result, Nemopilema nomurai were evenly distributed in all water layers in East China Sea in May and July. When considered the correlation by each survey methods, it is possible to identify jellyfish in the surface area by sighting method and using sampling net; however, it has a low correlation with acoustic estimates due to marine environmental factor such as weather condition, wind and atmospheric pressure. Therefore, the result can be utilized by basic data when estimating jellyfish’s distribution patterns and density estimates from each survey methods hereafter.

Interviews and boarding surveys were conducted in order to understand the actual usage of octopus pot in the coastal composite fishery in Jeollanam-do. According to the results of the interviews conduced by visiting the areas (Goheung, Yeosu and Wando), the number of octopus pots per nine-ton vessel were 30,000-80,000, and the number of daily usage pots were 7,000-10,000. The number of octopus pots per four-ton vessel was 40,000, and the number of daily usage pots were 4,000. As a result of the survey on two octopus pot fishing boats (9.77-ton and 4.99-ton) in Yeosu area, the daily catch weight of 9-ton class vessel was the minimum of 66.9 kg and the maximum of 159.6 kg. The daily catch weight of the four-ton class fishing vessel was from 31.3 kg to maximum 85.6 kg. The average number of octopus pot used per day in the nine-ton class vessel was 6,821 (the minimum of 6,031 and the maximum of 7,697) and 3,181 (the minimum of 2,282 and the maximum of 3,878) in the four-ton class vessel.

Unarmored dinoflagellates, in the family Kareniaceae, include harmful or toxic bloom-forming species, which are associated with massive fish kills and mortalities of marine organisms worldwide. The occurrence and distribution of the toxigenic species in the family Kareniaceae were investigated in the brackish and coastal waters of Korea between July 2018 and October 2020. During the survey, we collected seven newly recorded species; Karenia papilionacea, Karlodinium digitatum, Karl. veneficum, Karl. zhouanum, Takayama acrotrocha, T. helix, and T. tasmanica. A total of fifteen strains of the seven taxa were successfully established as clonal cultures and examined using LM, SEM, and molecular phylogeny inferred from LSU rDNA sequences. Herein, we present the taxonomic information, morphological features, and molecular phylogenetic positions of the unrecorded dinoflagellate species collected from Korean coastal waters.