After the United Nations Convention on the Law of the Sea (UNCLOS) and the United Nations Fish Stocks Agreement (UNFSA) came into effect, international cooperation through Regional Fisheries Management Organizations (RFMOs) was required, and each RFMO established and adopted the Conservation and Management Measure (CMM) for the regional Observer Programs to collect data on fishing activities and biological information and to monitor compliance with its CMMs. The observer coverage required by RFMO is set differently for each organization, ranging from 5% to 100%. In addition, tuna-RFMOs recommend increasing observer coverage in longline fisheries by at least 20% for reliable quantitative analysis of not only target species but also bycatch species and ecologically related species such as sharks, seabirds, sea turtles, and marine mammals. Therefore, in this study, we discussed ways to improve the national observer programs of Korean distant water fisheries that should be addressed in the future to respond to the RFMO trends.

The biological efficiencies of promising Pleurotus spp. were evaluated. Pleurotus ostreatus, Pleurotus tuberregium,and Pleurotus sajor-cajuwere investigated at temperatures of 22oC, 20oC, and 18oC to determine their ability to adapt to temperatures that are likely to be found in subtropical regions. The experiment was conducted using a substrate comprising Popular sawdust 60% + cotton seed 20% + beet pulp 20% under a relative humidity of 65%. The results indicated that there were significant differences in terms of biological efficiency between the species: P. tuber regium 128.84% at 22oC, P. ostreatus 108.41% at 22oC, and P. sajor-caju is 80% at 20oC. The common temperatures at which all species showed the highest biological efficiencies were 22oC and 20oC. Therefore, the production of the evaluated species was equal to or surpassed biological efficiencies reported in tropical environments, thereby demonstrating a potential opportunity to adapt to tropical environments without compromising quality standards.

Korean tuna purse seine fishery in the Western and Central Pacific Ocean (WCPO) began to operate in earnest in the early 1980s. Since then, the total catch has shown an increasing trend and the target species are skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacare) and bigeye tuna (Thunnus obesus). Based on the operational data of Korean tuna purse seine fishery from 2016 to 2020, the catch rates of target species (skipjack and yellowfin tunas) were analyzed by operation time for set types (free school and FAD sets). In the case of the free school sets, they were usually made from sunrise to sunset, and the catch rate was high before and after sunrise for skipjack tuna and before sunset for yellowfin tuna. On the other hand, for the FAD sets, more than 90% of them were made just before sunrise, and there were few operations during the daytime. The purpose of this study is to examine whether there are differences in the catch rate of skipjack and yellowfin tunas by operation time and by school type for Korean tuna purse seine fishery in the WCPO, which could be helpful in understanding its fishing characteristics and providing useful information for developing the stock indices of the target species.

The increase in temperature due to climate warming is predicted to affect crop yields in the future. Until now, various types of OTC (open top chamber) that simulate the future climate condition have been developed and used to study the effect of temperature increase due to global warming on maize growth. However, in most OTCs, high equipment and maintenance costs were required to artificially increase the temperature. This study was carried to develop a cost-effective and simple OTC suitable for climate warming experiments for forage maize. Three octagonal OTCs with a height of 3.5 m × a diameter of 4.08 m and a partially covered top were constructed. The lower part of OTC covered film was opened at a height of 26 cm (OTC-26), 12 cm (OTC-12) from the ground surface, or not opened (0 cm, OTC-0). Mean air temperatures during the daytime on a sunny day in OTC-0, OTC-12 and OTC-26 increased to 3.23℃, 1.33℃, and 0.89℃, respectively, compared to the ambient control plot. For a pilot test, forage maize, ‘Gwangpyeongok’ was grown at OTCs and ambient control plots. As a result, in the late maize vegetative growth phase (July 30), the plant height was increased more than 45% higher than the ambient control plot in all OTC plots, and the stem diameter also increased in all OTC plots. These results indicate that it is possible to set the temperature inside the OTC by adjusting the opening height of the lower end of the OTC, and it can be applied to study the response of forage maize to elevated temperature. An OTC, with its advantages of energy free, low maintenance cost, and simple temperature setting, will be helpful in studying maize growth responsiveness to climate warming in the future.

Tuna fisheries were applied to an integrated ecosystem-based fishery risk assessment method using indexes of target species status, inhabited species in a target ecosystem, habitat quality and socio-economic benefit of affected fisheries. This study suggested more effective and efficient management measures to break away from traditional management methods, such as limitation of catch and fishing effort. The results presented that the objective risk index (ORIS) on sustainability of bigeye and yellowfin tunas by purse seine fishery was estimated high due to the high catch ratio of small fishes. The ORIs of biodiversity (ORIB) and habitat quality (ORIH) of purse seine fishery were also estimated at a high level from using fish-aggregating devices (FAD). However, due to skipjack tuna’s high catches, the ORI of socio-economic benefit (ORIE) was estimated at a very low level. Due to the high bycatch rate, ORIB was high, and ORIS and ORIH were evaluated at a low level in longline fishery. Due to strengthern of fishing restrictions and increase of fishing costs, the ORIE was assessed to be very high. The ecosystem risk index (ERI) for two tuna fisheries was assessed low, but the overall FAD management by purse seine fishery is necessary at the ecosystem level.

In order to understand characteristics on bycatch of Korean tuna purse seine fishery, especially operations associated with Fish Aggregating Device (FAD) in the Indian Ocean, we conducted analyses related to bycatch by school association type (unassociated school, FAD associated school and log associated school) using the data collected by scientific observers from 2016 to 2018. The FAD used by Korean tuna purse seine fishery in the Indian Ocean was a drifting FAD, which belongs to non-entangling FADs according to the category proposed by the International Seafood Sustainability Foundation (ISSF). The target species of Korean tuna purse seine fishery are skipjack, yellowfin and bigeye tunas, accounting for 99% of the total catch. The ratio of bycatch was 0.97% in total catch and the discard accounted for less than 1%, indicating that most catch was retained on board. In terms of bycatch ratio by school association type, it accounted for 0.12% for unassociated school, 1.09% for FAD associated school and 1.25% for log associated school. As for the catch proportion of shark species by school association type, it accounted for 0.01% for unassociated school, 0.11% for FAD associated school and 0.10% for log associated school, which showed that unassociated school type was the lowest to affect bycatch of non-target and shark species. Given the proportion of bycatch compositions, however, it is considered that FAD associated school of Korean tuna purse seine fishery has less caught bycatch species of non-target and shark, compared to other fleets operating in the Indian Ocean.

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.

The purpose of this study is to analyze the efficiency of distant-water longline fishing vessels in the Pacific Ocean and the gap in efficiencies among individual vessels. In order to estimate the efficiency, the dependent variable is set as an amount of catch and independent variables include number of crew, number of hooks, number of vessel size, and vessels engine power associated with fishing activities of distant water longline fisheries. Analytical result was shown as follows: first, the average efficiency of distant-water longline fishing vessels in the Pacific Ocean was found to be 94%. Second, the number of hooks were found to be statistically significant in each input variable and the appropriate control of the number of hooks would be expected to have a positive effect on the efficiency. Third, the relationship between the age of a vessel and the efficiency was not found statistically.

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.

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.

Fishing trend and 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 2013. The historical catch of this fishery had sharply increased since mid–1980s, and it has shown fluctuations with about 2–3 hundred thousands, whereas the catch per number of vessel has steadily increased with fluctuations since commencing this fishery. As for the proportion of catch by set type, unassociated type had increased from the mid–1980s to the end of 1990s, and then has decreased up to 2010s. Associated type had decreased continually to the end of 1990s, however, it started to increase since the beginning of 2000s. As for the catch proportion of set type by main species, those of skipjack tuna and bigeye tuna showed higher in the associated type, whereas that of yellowfin tuna has the highest proportion in the unassociated type. Fishing distribution of Korean tuna purse seine fishery was concentrated on the area of 5°N~10°S and 140°E~180° through the decades. The monthly catch distribution by longitudinal zone of Korean tuna purse seine fishery expanded the most further to the eastward in September to October.

To examine species composition, abundance and biomass of fishes in the northwestern East Sea of Russian EEZ, trawl survey were conducted at 31 sampling stations from 2006 to 2008. Also, trawl survey were conducted at 21 sampling stations in the southwestern East Sea of Korean EEZ from 2006 to 2008. A total of 67 fishes were collected in the northwestern East Sea of Russian EEZ, a total of 39 fishes were collected in the southwestern East Sea of Korean EEZ. Among them, a total of 53 fishes were collected in the northwestern East Sea of Russian EEZ only, and a total of 25 fishes were collected in the southwestern East Sea of Korean EEZ only. Mean abundance per area which caught by trawl survey in the northwestern East Sea ranged from a high of 116,478 inds./km2 in 2008 to a low of 19,737 inds./km2 in 2006. And mean abundance per area in the southwestern East Sea ranged from a high of 89,129 inds./km2 in 2006 to a low of 8,234 inds./km2 in 2008. Mean biomass per area which caught by trawl survey in the northwestern East Sea ranged from a high of 11,333 kg/km2 in 2008 to a low of 2,439 kg/km2 in 2006. And mean biomass per area in the southwestern East Sea ranged from a high of 6,273 kg/km2 in 2006 to a low of 1,062 kg/km2 in 2008. Cluster analysis, based on a Bray–Curtis similarity matrix of fourth root transformed data of number of species and individuals per area, showed division into three different groups by depth in the northwestern and southwestern East Sea.

Dietary and lifestyle modifications are widely prescribed to prevent recurrence of urolithiasis, although little is known about the clinical and demographic factors associated with patient compliance and urinary metabolic changes. The present study assessed the clinical and demographic factors influencing compliance with a modified diet and lifestyle in first-time ureteric stone formers as well as determined the effects of compliance on urinary stone risk factors. We retrospectively reviewed the medical records of 53 patients presenting with ureteric calcium stones. Using a self-completed questionnaire, patients were classified according to compliance with seven recommendations for modifying diet and lifestyle into good compliance group (complied with ≥ three recommendations) and poor compliance group. Before (on a random diet) and after prescribing the modifications, 24 hour urine samples were collected from those in the good and poor compliance group. The stone size at presentation and initial treatment modality were closely associated with patient compliance (P=0.019, P=0.027, respectively). Citrate excretion significantly increased in the good compliance group after adopting modifications (P=0.012), whereas the poor compliance group did not show a statistically significant difference. Moreover, patients in the poor compliance group showed significantly increased urinary calcium excretion by the end of the study (P=0.040). After adjustments for age, sex, body mass index, and metabolic abnormality status, poor compliance was found to be an independent risk factor for persistence or development of hypocitraturia (OR: 3.885; 95% CI: 1.102~13.694; P=0.035). In conclusion, our results imply that patient education programs regarding diet and lifestyle should be tailored to the individual’s clinical and demographic characteristics.

Maturity and spawning of the giant Pacific octopus, Octopus dofleini was investigated based on the samples collected in the coast of Gangwondo, East Sea, from January to December in 2009. Individuals of mature stage had a higher occurrence rate from February toMay, and gonadosomatic index (GSI) also showed a higher value from February toMay than the other months. For that reason, the spawning period was estimated from February to May with the main spawning period from March to May. The total number of eggs in the fecundity (F) ranged from 9,045 in 11.0 kg (TW) to 148,682 in 16.5 kg (TW), which was proportional to total weight (TW), and the relationship between total weight and fecundity was F=0.185×TW2.238 (R2=0.389). The total weight at 50% group maturity (TW0.5) of female was estimated to be 12.2 kg.

To compare the catches made using gillnets, trammel nets, and gillnets with supporting lines, several experiments were conducted with commercial vessels near Uljin and Pohang in Eastern Korea between July 2010 and May 2011. Two sets of 13 different nets were used, including 5 panels of gillnets and trammel nets each with stretched mesh sizes of 7.6, 9.1, 10.6, 12.1, and 13.6 cm and 3 panels of gillnets with a mesh size of 9.1 cm with supporting lines with different line spacing. The outer (stretched) mesh size of the trammel nets measured 51.5 cm. The target fishes of the fishing nets were various types of flounders. The catch rate of flounders was 50.7% of the total catch in weight. The total catch for all nets was 443.8 kg. The predominant species was pointhead flounder (Cleisthenes pinetorum). The total catch by trammel nets was 1.4 times that of the comparable gillnets. But more pointhead flounder were caught by gillnets than by trammel nets, though there was no significant difference. Fishermen catching the pointhead flounder in Korea said that there was no need to use trammel net to catch it; this was an unexpected finding compared to the findings of other flounder fisheries. The amounts of roughscale sole, brown sole, and blackfin flounder caught by trammel nets were greater than those caught by gillnets. The mean lengths (standard deviation) of blackfin flounder, pointhead flounder, brown sole, and roughscale sole were 21.0 (4.57), 22.9 (3.40), 24.7 (4.90), and 28.3 (5.43) cm, respectively; there were significant differences in mean length (p < 0.00001). Therefore, in order to catch flounder efficiently, the fishing nets and mesh size should be chosen according to the target species. One advantage of using supporting lines is that it prevents breakage by strengthening the material especially when utilized on a rough bottom. Catch by using gillnet with supporting lines was not greater than that by using trammel net for the conservation of fisheries resources.

Injection of nematicides such as emamectin benzonate and milbemectin is the most common practice to control the pinewood nematode, Bursaphelenchus xylophilus, in Korea. These macrocyclolactone nematicides, however, are expensive, limiting their practicability despite of high efficacy. In an attempt to screen affordable alternative organophosphate (OP) and carbamate (CB) nematicides, we identified and characterized three acetylcholinesterases (ACE, EC 3.1.1.7) from B. xylophilus and functionally expressed them using baculovirus system. In inhibition assay using 11 OPs and 3 CBs, all the three ACEs were highly inhibited by paraoxon, DDVP, chlorpyrifos-oxon and mevinphos of OPs and carbofuran and carbaryl of CBs but not inhibited well by the others. Interestingly, inhibition assay revealed that BxACE-3 is less sensitive to all insecticides tested than other two ACEs. In additional bioassay, chlorpyrifos, DDVP and parathion showed a high LC50 but all CBs tested did a very low mortality. The inhibition kinetic data and bioassay data obtained in this study should provide essential information for the development of OP-based nematicidal agents against B. xylophilus. Availability of expressed ACE will also facilitate the development of in vitro screening system to develop potential OP nematicides.

The pinewood nematode, Bursaphelenchus xylophilus (Steinner & Buhrer) Nickle, has two different life stages according to several environmental factors: dispersal stage and propagative stages. The dispersal stage is closely related to the migration to other host pines, whereas the propagative stage is coupled to the direct cause of pine wilt. To establish expressed sequence tag (EST) database of two life cycles of B. xylophilus, subtractive EST libraries were constructed using suppressed subtractive hybridization (SSH). From 3,072 and 3,840 sequences of dispersal- and propagative-specific stage cDNA libraries, 1,927 and 2,604 clusters were generated, respectively, which were annotated by BLASTx and Gene ontology (GO). A total of 1,112 (57.7%) and 1,215 (46.7%) clusters from the dispersal- and propagative-specific stage cDNA libraries respectively had the matched BLASTx hits (E≤10-2), among which 913 (47.4%) and 960 (36.9%) were classified into three categories in Gene ontology. From GO database, some respective stage-specific genes were searched and estimated the relative transcripts level according to stages using the quantitative real-time PCR.