• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.3
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• pp.251-261
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• 2022

Tuna purse seine fishery (TPF) constitute more than 60% of distant water fishery production in Korea based on a statistic of 2018, and 28 ships from four different companies were under operation at the western and central Pacific Ocean. On this research, common risk factors during TPF were investigated via enumeration of five years Korean fisherman's insurance payment statement, followed by some counterplans to diminish the accident rate. The accident rate of TPF on the Pacific Ocean peaked by 43.0% in 2014 and constantly decreased to 23.0% until 2018, presenting an average of 33.6%. Meanwhile, the accident rate on the Indian Ocean reached the highest point 55.1% in 2014 and declined to 11.6% in 2016, having an average of 24.7%. The average accident rate of the Indian Ocean scored 8.9% lower than the rate of the Pacific Ocean, but no statistic significance was observed. Depending on the process of operation, 'casting or hauling of net' was the most frequent part that people received an injury (40.4%). When the accidents were classified by their types, 'falling down' was the most recurrent cause of the injuries (28.5%). At the point of severity, the worst injuries were induced by crush hazard. Considering aforementioned accident frequency and severity, all the factors on the accident type list were divided into three different groups including high risk, moderate risk, and common risk. This study is expected to contribute to the reduction of occupational accidents during the work of fishermen and establishment of a safety management system for distance water fishing vessels.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.1
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• pp.20-28
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• 2019

The feeding habits of Pacific bluefin tuna, Thunnus orientalis were analyzed using samples by large purse seine fishery in Korean waters from 2012 to 2017. The number of samples was 1,274 and the fork-length (FL) ranged from 34.6 to 218.0 cm. According to %IRI, the Important main prey items of immature individuals (below 91.4 cm in FL) were Pisces, Cephalopoda and Euphausiacea and those of mature individuals were Cephalopoda and Pisces. T. orientalis showed ontogenetic changes in prey item that Pisces was dominated in size class of 30-89 cm (FL), Cephalopoda in 90-179 cm (FL), and Pisces above 180 cm. As for seasonal changes in prey item, Cephalopoda was dominant in spring and Pisces was dominant in summer, autumn and winter. %F, %N, %W and %IRI cluster analysis divided area into three groups: Group A was dominated by Pisces; Group B was dominated by Cephalopoda, and Group C was dominated by Euphausiacea.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.810-817
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• 2018

In Korea, tuna purse seine fishery is the industry with the highest production volume in domestic deep-sea fishery. Research has been continuously carried out since the late 1980s, and research on modernization of technology has been actively conducted. However, while auxiliary works boats on the fishing vessels play an important role in the purse seine fishing, related research is not sufficient. In this study, we tried to rebuild the propulsion system of the Net-boat from the propeller to the waterjet type and to perform the hull form conversion to improve the resistance performance of the hull part and improve the motion performance. For this, we calculated the change of the fluid performance of the ship through computational numerical analysis. In addition, towing tank tests were carried out to verify the performance of the existing ship and the ship which changed the propulsion system. As a result, resistance performance of the waterjet type compared to the propeller type was improved by approximately 45 %. It was confirmed that this was due to reduction of the wetted surface area by removing net and improvements in hull form.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.553-560
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• 2015

The feeding habits of the Pacific bluefin tuna, Thunnus orientalis were examined based on the stomach contents of 330 specimens caught by offshore large purse seine fishery in the southern sea of Korea, 2011. The size of Pacific bluefin tuna used in this study ranged from 34.1 to 67.3 cm in fork length (FL). The percentage of empty stomachs was 41.8%. The main prey items were Pisces and Cephalopoda based on percentage IRI (index of relative importance). The main fish preys were Trachurus japonicus, Bregmaceros japonicus, Engraulis japonicus, and Cephalopoda were Todarodes pacificus, Loligo edulis, Watasenia scintillans. T. orientalis showed ontogenetic change in diet composition. Although Pisces dominated the diet of all length classes the portion of Cephalopoda was relatively higher in size between 40 and 50 cm other than length classes. In terms of seasonal variation in feeding habits, Pisces was the main prey group in all seasons, but Cephalopoda was also frequently consumed during spring and autumn based on %IRI.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.3
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• pp.377-385
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• 2015

The age and growth of the skipjack tuna Katsuwonus pelamis were determined using otoliths sampled from a Korean tuna purse seine fishery in the Western and Central Pacific Ocean from January 2005 to September 2006. A total of 312 otoliths were used to estimate the ages of skipjack tuna, which ranged from 1 to 7 years. The relationships between otolith ring radius (R) and fork length (FL) for female, male, and sex combined were FL = 19.74R + 1.50 ($r^2=0.54$), FL = 17.66R + 6.35 ($r^2=0.47$), and FL = 18.83R + 3.36 ($r^2=0.53$), respectively. The back-calculated fork lengths of each age ($FL_{year}$) were $FL_1=36.2cm$, $FL_2=43.3cm$, $FL_3=48.3cm$, $FL_4=52.6cm$, $FL_5=56.5cm$, $FL_6=60.8cm$, and $FL_7=63.2cm$. The relationships between fork length (FL) and total weight (TW) for female, male, and sex combined were $TW=0.00001FL^{3.19}(r^2=0.95)$, $TW=0.00001FL^{3.17}(r^2=0.95)$, and $TW=0.000009FL^{3.23}(r^2=0.95)$, respectively. The von Bertalanffy growth parameters of skipjack tuna estimated in this study were $L_{\infty}=77.4cm$, K = 0.176/year, and $t_0=-2.569years$.