• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.2
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• pp.169-176
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• 2017

Tuna purse seine fishery in the western and central Pacific Ocean (WCPO) has been rapidly developed since early 1980s due to massive investment of major distant water fishing nations, and catch by purse seine fishery operating in the WCPO accounts for nearly half of the world's tuna total catch. As fishing efficiency is reflected by not only improving of individual vessel's capacity but also increasing number of active vessel, it is essential to understand vessel capacity for reliable assessment result on how fishery affects stock status of target species. In this study, fishing efficiency was analyzed by main factors which are representative of vessel capacity using fishing data and vessel information related to Korean tuna purse seine fishery operating in the western and central Pacific Ocean from 1992 to 2014. It showed that fishing efficiency of vessel tends to be higher when having larger vessel tonnage, higher engine power, lower vessel age and larger length of vessel. As for fishing efficiency by set type, CPUE of associated set with floating objects was generally higher than that of free school set, and CPUE of free school set seemed to have a greater effect on engine power and vessel age compared to other factors.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.1
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• pp.1-8
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• 2016

In this study, numerical method was used to assess technical properties and improve the Vietnamese tuna purse seine. The data were extracted from the two national level projects. The study results showed that average lead-line sinking speed reached 0.139 m/s and 0.143 m/s and maximum sinking depth was 61.6 m and 65.8 m for The gears 2003 and 2014 respectively. The maximum tension on ring line of The gear 2003 was 4,742 kgf and 2014 was 4,219 kgf. The improved tuna purse seines I, III and IV showed similar sinking speed results with 0.220 m/s, 0.219 m/s and 0.219 m/s respectively. The average lead-line sinking speed of the improved gear II was lowest with 0.215 m/s. The maximum lead-line sinking depth of the four improved gears I, II, III and IV were 116 m, 112 m, 115 m and 114.9 m respectively. Maximum tension on ring line of the improved gears I, II, III and IV were 5,657 kgf, 5,406 kgf, 5,645 kgf and 5,654 kgf respectively. The improved tuna purse seine IV is the most suitable for Vietnamese tuna purse seine fishery, Which corresponds with tuna purse seiner scale and its fishing supporting equipment at the present.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.2
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• pp.108-117
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• 2011

In order to offer data about fisheries resources management and prediction of catch on large purse seine fisheries, the fluctuation of the fisheries condition and distributions of fishing ground for mackerel were analysed with monthly catch data for 1990.2009. The overall catch has decreased to about 70% since 1997, with approximately 70% of the mackerel (Scomber japonicus) catch and monthly fluctuations showing a similar pattern. Monthly distribution of fishing ground is like distribution of mackerel in large purse seine fishery. The main fishing grounds are near Jeju Island and the Yellow sea with the main fishing season existing between October to December. The catches fluctuations and distribution of fishing ground were related to the effect of regime shifts. Therefore, in order to prediction of catch on large purse seine fisheries should be studied these relationships.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.1
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• pp.12-18
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• 2017

Lots of fishery stocks are overexploited and the overcapacity exists in Korean fishing fleets. One of the reasons is technological development, which increases the efficiency of the vessels continuously. The analysis was conducted to identify the change of fishing power index to develop the vessel and gear technology that may have improved the fishing efficiency of the offshore large powered purse seine fishery from 1960s to 2010s. Gross tonnage and horse power per fishing vessel was increased annually. Fishing gear material was changed to the knotless webbing to settle faster. Fishing equipments was modernized and supply rate was also increased. Therefore the relative fishing power index in the offshore large powered purse seine fishery increased from 0.4 in 1970 to 1.0 in 1980, to 1.5 in 2000 and to 1.6 in 2010, but the rate of increase slowed down gradually. The results are expected to contribute to reasonable fishery stock management.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.3
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• pp.282-290
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• 2013

The global warming related to GHG (greenhouse gases) emissions from industries is a major issue globally. Furthermore, GHG emissions from the fishery industries also represent an important issue, as indicated by "The Code of Conduct for Responsible Fisheries" at the Cancun, Mexico, meeting in 1992 and by the Kyoto protocol in 2005. Korea pronounced itself to be a voluntary exclusion management country at the 16th IPCC at Cancun, Mexico, in 2010. However, few analyses of GHG emissions from Korean fisheries have been performed. Therefore, a quantitative analysis of GHG emissions from the major Korean fisheries is needed before guidelines for reducing GHG emissions from the fishing industry can be established. The aim of this study was to assess the present GHG emissions from the Korean Purse seine fishery using the LCA (life cycle assessment) method. The system boundary and allocation method were defined for the LCA analysis. The fuel consumption factor of the purse seine fishery was also calculated. The GHG emissions for the edible fish were evaluated by determining the weights of whole fish and gutted fish. Finally, the GHG emissions required to produce 1kg of whole fish and 1kg of edible fish were deduced. The results will help determine the GHG emissions from the fishery. They will also be helpful to stakeholders and the government in understanding the circumstances involved in GHG emissions from the fishing industry.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.1
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• pp.12-27
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• 2007

This fundamental studies on for the productivity improvement and laborsaving of purse seine fishery. Given the difficulty posed from the distortion of net shape caused by the external forces, such as tide, at the time of shooting and pursing, we set the 4 steps of 0, 2, 4 and 6cm/sec in flow velocity in the flume tank for the experiment in order to examine those characteristics. We used two model seines designed on the scale of 1 to 180 based on the power block seine, which is the mackerel purse seine generally used in the near sea of Jeju Island and triplex seine, which is the mackerel purse seine of one boat system fishing expected in the future, for the experiment, and interpreted the characteristics of several motion in water, such as the shape of seine, the change in tension and area during pursing and its the analysis results are as follows. Though the experiment could be conducted up to 6cm/sec of flow velocity that was defined, the experiment could not go on because of the severe distortion in the seine at the flow velocity in excess of 6cm/sec. As for the depth of leadline and reduction rate of side area of seine when the pursing is connected, P seine turned out to be slightly higher than T seine, and the hauling speed and reduction rate of upper area of seine were found similar to each other. The correlation between the hauling time (Ht) and depth of lead line (Dhp, Dht) of P seine and T seine can be expressed by the equation, that is, Dhp=(0.99Pt-7.63)Pt+69.01, Dht=(1.03Pt-7.73)Pt+66.74. The correlation between the hauling time and hauling velocity (Hpp, Hpt) can be expressed by the equation, that is, $Hpp=-0.06Ht^2+0.88Ht+0.78,\;Hpt=-0.05Ht^2+0.81Ht+0.98$ here, Pt is pursing time. And the correlation between the pursing time and the reduction rate of side area (sArp, sArt) can be expressed by the equation, that is, $sArp=-0.48Pt^2+14.79Pt-16.74,\;sArt=-0.45Pt^2+14.56Pt-16.48$. The reduction rate of upper area of seine (tArp, tArt) can be expressed by the equation, that is, $tArp=0.34Pt^2-0.66Pt-0.74,\;tArt=0.34Pt^2-0.27Pt-1.80$. In addition, the correlation between the pursing time and tension of purse line (Tep, Tet) can be expressed by the equation, that is, $Tep=2.79Pt^2+2.26Pt-0.60,\;Tet=2.14Pt^2+8.08Pt-27.50$.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.4
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• pp.263-270
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• 2005

This paper summarizes characteristics of the Korean tuna purse seine fishery in the Western and Central Pacific Ocean (WCPO). Major fishing area for the Korean tuna purse seine fleet consisted of the waters of Micronesia, Papua New Guinea and Solomon Islands and adjacent high seas between $130^{\circ}E-180^{\circ}$ The center of the Korean tuna fishing ground was in the vicinity of $180^{\circ}$ during the El - $Ni{\tilde{n}}$o event but was formed in $150^{\circ}-160^{\circ}$E during the La - $Ni{\tilde{n}}o$ event. As compared with other major purse seine fleets in WCPO, the Korean fleet set more on unassociated schools of tuna, while Japan, USA and Chinese - Taipei fleets accounted for more than 50% of sets on log - associated schools. In general, CPUES for log - associated schools were higher than those for unassociated schools and catch composition showed that yellowfin ratio was higher in unassociated shools than log - associated schools. Length frequency represented higher percentage of mid - sized yellowfin than Japanese and USA fleets. Daily set numbers and CPUE were high before 7 am and remained almost constant from 7 am to 3 pm but decreased rapidly after 3 pm and 5 pm, respectively. Catch composition per set indicated that pure skipjack school was caught most frequently, followed by mixed school and pure yellowfin school as the least, but CPUE was highest for the mixed school.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.3
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• pp.173-182
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• 1997

This study is a basic research in purse seine fishery : on the behaviour of fish schools of tilapia Tilapia mossambica in the process of catch of the purse seine fishing method. The experiment was carried out for the mackerel purse seine which using of power block by fishing fleet system in the near sea of Cheju Island and as a forecast in the near future on the purse seine fishing, using of triplex net winch by one boat system in the near sea of Norway. These model purse seines were made of the scale of 1/180 of its full scale. The model purse seine test on the escaping behaviour of fish school by gap, area reducing of gap and tension of purse line was carried out in the stagnant water of experimental water tank. Designing and testing for the model purse seines were based on the Tauti's law. The results obtained were as follows : 1. When the time for the completing of pursing was 20 minutes, average swimming speed of fish school through a gap was 9.71cm/sec for powerblock seine and 9.97cm/sec for triplex seine. 2. In the case of pursing time in actual value was 20minutes, at 50 percent of the pursing, swimming behaviour of fish school in purse seine was 10% to I section, 80% to II section, 10% to III sectional direction for powerblock seine and a similar tendency for triplex seine. 3. In the case of pursing time in actual value was 20 minutes, at the time of 10 minutes have proceeded since then, area reducing rate of gap of the seine in projected front view was 63.5% for powerblock seine and 67.5% for triplex seine. 4. In the case of pursing time in actual value was 20 minutes, escaping rate of fish school by gap in projected front view was 70% for powerblock seine and 30% for triplex seine. Maximum tension of purse line was about 8.1 tons for powerblock seine and about 8.3 tons for triplex seine.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.2
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• pp.99-111
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• 2003

The fundamental studies on the productivity improvement of the purse seine fishery are presented in this paper. The experiment on net shooting and hauling was carried out in the near sea of Jeju Island (33$^{\circ}$37.8' N, 126$^{\circ}$31.1' E) by using the Cheju national university training ship (A-Ra, 990tons) which was constructed for the one boat system operation of purse seine. The corkline and leadline of the purse seine used for the experiment were 829.1m and 995.7m in length, respectively. Micro data recorder system, net sonde, and tensiometer were used to measure the depth of leadline and the tension of purse seine. Based on the measurement data, the motion and tension of purse seine at the time of shooting, hauling, and pursing were characterized. The experimental results are summarized as follows ; 1. The shooting and hauling of net were found to be possible in the one boat system experimental operation. 2. At the time of purse seine shooting, the relationship between the depth (Dp) of leadline and elapsed time (Et) was found to be Dp=7.58Et-6.48. 3. At the time of pursing, the relationship between the depth (Dp) of leadline and elapsed time (Et) was found to be Dp=-0.8Et$^2$＋7.42Et＋92.04. 4. At the time of pursing, the tension (metric tons) of purse seine attained its maximum value (14.7tons) when the elapsed time is 8 minutes. The relationship with the elapsed time was found to be T=-0.13Et$^2$＋3.23Et-5.72.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.2
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• pp.149-161
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• 2016

Fishing characteristics of Korean tuna purse seine fishery in the Pacific Ocean were investigated using logbook data compiled from captain onboard and the statistical data from 1980 to 2014. Changes in fishing ground and correlation between marine environmental factors and fishing patterns were investigated using Oceanographic index. The proportion of unassociated set was higher than that of associated set. The catch proportion of yellowfin was higher in the unassociated set, while that of skipjack and bigeye was higher in the associated set. Due to vessels, fishing gears and Korean captains' high-level of skills in fishing technology optimized for the unassociated set and preference of large fishes, especially large yellowfin tuna, it showed unique fishing characteristics focusing on the unassociated set. As for fishing distributions of Korean tuna purse seine fishery and impacts of oceanographic conditions on the fishery, the main fishing ground was concentrated on the area of $5^{\circ}N{\sim}10^{\circ}S$, $140^{\circ}E{\sim}180^{\circ}$ through the decades. When stronger El-nino occurred, the range of fishing ground tended to expand and main fishing ground moved to the eastern part of western and central Pacific Ocean. During this season, yellowfin tuna had high CPUE and catch proportion of yellowfin tuna in the eastern part also increased. As for the proportion of fishing effort by set type, proportion of log associated set was high during El-nino season while that of FAD associated set was high during La-nina season.