In this study, a drifting test using a experimental vessel (2,966 tons) in the northern waters of Jeju was carried out for the first time in order to obtain the fundamental data for drift. During the test, it was shown that the average leeway speed and direction by GPS position were 0.362 m/s and 155.54° respectively and the leeway rate for wind speed was 8.80%. The analysis of linear regression modes about leeway speed and direction of the experimental vessel indicated that wind or current (i.e. explanatory variable) had a greater influence upon response variable (e.g. leeway speed or direction) with the speed of the wind and current rather than their directions. On the other hand, the result of multiple regression model analysis was able to predict that the direction was negative, and it was demonstrated that predicted values of leeway speed and direction using an experimental vessel is to be more influential by current than wind while the leeway speed through variance and covariance was positive. In terms of the leeway direction of the experimental vessel, the same result of the leeway speed appeared except for a possibility of the existence of multi-collinearity. Then, it can be interpreted that the explanatory variables were less descriptive in the predicted values of the leeway direction. As a result, the prediction of leeway speed and direction can be demonstrated as following equations. However, many drift tests using actual vessels and various drifting objects will provide reasonable estimations, so that they can help search and rescue fishing gears as well.

Marine accidents caused by ships are very diverse, such as collision, sinking, stranding, grounding and fire. In particular, persons on passenger ship are unspecified and not trained, so it makes evacuation harder. For this reason, an evacuation plan that considers diverse situation in ship is needed. Effective evacuation planning requires training in consideration of various evacuation situations. In this paper, we investigated the time elapsed on evacuation in various situations from “HANMIR,” the fishery training ship of the Korean Institute of Maritime and Fisheries Technology, using a Ship Evacuation Analysis Program (SEA-Pro) which is introduced to the society. We assumed a situation that has not only inconveniences for real training but also the possibilities of happening. Not all trainees are resting in their cabin, so we assumed positions such as they are in the bridge or engine room and applied fire and flooding situations. We assumed that the time for alerting the situation would be short, so we applied only elapsed time of movement. Those analyses could be helpful in three ways. The first is predicting the consequence of possible accidents. There are some conditions that can be appliable to this model, such as the decreased area of sight in those situations. The second is concluding the optimal limit of carriage and placement of safety instruments on building a new ship. The third is to be a base data for ships to make a new effective evacuation plan based on these analyses.

The distribution of tidal current and tidal induced residual current, topographical eddies and tidal residual circulation in the waters surrounding the Geumo Island-An Island channel were identified through numerical model experiments and vorticity balance analysis. Tidal current flows southwest at flood and northeast at ebb along the channel. The maximum flow velocity was about 100-150 cm/s in neap and spring tide. During the flood current in the neap tide, clockwise small eddies were formed in the waters west of Sobu Island and southwest of Daebu Island, and a more grown eddy was formed in the southern waters of Geumo Island in the spring tide. A small eddy that existed in the western waters of Chosam Island during the ebb in neap tide appeared to be a more grown topographical eddy in the northeastern waters of Chosam Island in spring tide. Tidal ellipses were generally reciprocating and were almost straight in the channel. These topographical eddies are made of vorticity caused by coastal friction when tidal flow passes through the channel. They gradually grow in size as they are transported and accumulated at the end of the channel. When the current becomes stronger, the topographic eddies move, settle, spread to the outer sea and grow as a counterclockwise or clockwise tidal residual circulation depending on the surrounding terrain. In the waters surrounding the channel, there were counterclockwise small tidal residual circulations in the central part of the channel, clockwise from the northeast end of the channel to northwest inner bay of An Island, and clockwise and counterclockwise between Daebu Island and An Island. The circulation flow rate was up to 20-30 cm/s. In the future, it is necessary to conduct an experimental study to understand the growth process of the tidal residual circulation in more detail due to the convergence and divergence of seawater around the channel.

Two specimens of Hemitrygon izuensis (395.8-471.5 mm in disc width), belonging to the family Dasyatidae (Myliobatiformes), were collected from the waters off north-eastern Jeju-do Island in June 2016 and Pohang in August 2019. This species was characterized by having no spots on dorsal side of disc, white ventral tail fold and short preorbital snout length (15.6-18.3% of disc width). This species is similar to H. akajei and H. sinensis reported in Korea, but differs in small denticles on mid-line of dorsal surface of disc (absent in H. izuensis vs. present in H. akajei and H. sinensis), the length of ventral tail fold (28.1-31.0% in H. izuensis vs. 48.0-48.6% in H. akajei vs. 45.0% in H. sinensis), color of ventral tail fold (white in H. izuensis vs. black in H. akajei and H. sinensis) and small tubercles on the posterior part of tail (absent in H. izuensis vs. present in H. akajei and H. sinensis). We suggest a Korean name for H. izuensis as “I-ju-gal-saeg-ga-o-li” following Kim et al. (2019).

The research was analyzed the catch data of the five years (2016-2020) for six joint venture company tuna purse seiners in the Atlantic Ocean, with the aim of suggesting improvement measures for responsible and sustainable fishing according to changes of recommendation by International Commission for the Conservation of Atlantic Tuna (ICCAT) on the tropical tunas. In the last five years, the average catch of six tuna purse seiner gradually increased to 7,745 tons, 8,364 tons and 9,053 tons from 2016 to 2018, but decreased to 7,761 tons in 2019 and 6,214 tons in 2020. The reason for the decrease in fishing volume in 2019 and 2020 was the fluctuation of the formation of the cold water zone (22-23℃), and the total ICCAT convention area of FAD closure in January and February due to the expansion of the FAD closure area and poor free school catching during two months period, respectively. The analysis on fishing area showed that the percentage of fishing in the high sea was about 85% although the FAD closure area included the EEZ zone in coastal countries; the rise of the fishing license in coastal countries is also believed to be a factor. In order to overcome such situations and improve catching volume, it will be possible if excellent manpower is secured, school fishing is expanded, and the production of high value-added catch (purse seine special: PS).

This study was conducted to evaluate the performance of the octopus pot according to mesh sizes. Entering behavior of Octopus minor and bait (Macrophthalmus japonicus) escape rate on the mesh sizes of the pots were investigated for six times in indoor tank. The sea trials for evaluating the performance of Octopus minor pot to different mesh sizes (22, 20 and 18 mm) were conducted for six times from 2017 to 2018 in the coastal sea of Deukyang Bay, the Republic of Korea. Behavior patterns of contact pot to leaved pot were more frequent than contact pot to bait search. When the octopus contacted to the pot, there was no clear search behavior to distinguish the mesh sizes. Total catch of 46% was accounted for 18 mm pots, followed by 34% at 20 mm and 20% at 22 mm (P < 0.05). Catch per unit effort was calculated as 30 g/pot at 22 mm, 44 g/pot at 20 mm and 59 g/pot at 18 mm. As a result of evaluating 50% selection of mantle length and weight on the mesh sizes, mantle length (mm) and weight (g) were 84.6 and 147.8 in 22 mm, followed by 20 and 18 mm.