• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.155-158
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• 2001

In order to investigate the influence of sea condition on the catch fluctuation of long line for common octopus, octopus variabilis. the oceanographic factors. I .e., the water temperature, the salinity and the density in the coastal waters of Yosu from Jan 11 to Jul. 25 in 1997 and compared with the catches of common octopus, octopus variabilis by long line. The results obtained summerized as follows ; 1) The range of water temperature, salinity and density from Jan. to Jul. at the sea area were 4.1∼23.6℃. 31.7∼34.5‰ and 21.30∼27.81. respectively, and the catch of common octopus, octopus variabilis was high respectively at the temperature of 17∼20℃ at the salinity of 33.0∼33.5‰ and at the density of σ/sub t/ 22.5∼24.0. 2) The catch of common octopus. octopus variabilis was lowest from Jan. to Feb. and highest from May to June.

• Environmental and Resource Economics Review
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• v.19 no.4
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• pp.897-914
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• 2010

The translog cost function of Korean Walleye pollock fishery is used to examine the impact of surface water temperature change led by global climate change. Catched of walleye pollock are very sensitive to water temperature and material cost. Elasticities of production to water temperature are -9%, significantly lower than we expected. There may be alternative explanations for the productivity decrease, including the possibility of overfishing and water pollution. However, the impact of climate change is obvious and inevitable. Therefore the government may encourage local fishermen to change from current cold water to warm water fisheries. Moreover continuos monitoring for the possibility of illegal activities at the East Sea. Finally, collaborated political efforts may be needed among the nations in the East Sea to conserve a Walleye Pollock fishery.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.4
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• pp.321-325
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• 2001

In order to investigate the influence of sea condition on the catch fluctuation of long line for common octopus, octopus variabilis, the oceanographic factors, i. e., the water temperature, the salinity and the density in the coastal waters of Yosu from Jan. 11 to Jul. 25 in 1997, and compared with the catches of common octopus, octopus variabilis by long line. The results obtained summerized as follows; 1) The range of water temperature, salinity and density from Jan. to Jul. at the sea area were 4.1~$23.6^{\circ}C$, 31.7~34.5$\textperthousand$ and 21.30~27.81, respectively, and the catch of common octopus, octopus variabilis was high respectively at the temperature of 17~$-20^{\circ}C$, at the salinity of 33.0~33.5$\textperthousand$ and at the density of $\sigma$t 22.5~24.0. 2) The catch of common octopus, octopus variabilis was lowest from Jan. to Feb. and highest from May to June.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.194-201
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• 2022

Purpose: This study investigated the relationship between climate factors and the catches in Korean offshore fisheries in recent three decades (1981 to 2010). Method: This study focused on seven types of fish species preferred in Korean cuisine. In the study, 10-year moving averages were used so that long-term trends could be easily identified. Results: Both air temperature and sea surface temperature (SST) on the coast of Korea rose in the period (p < 0.05). The rise in SST was significantly correlated with the rise in air temperature (p < 0.05), but not with precipitation. In the 2010s compared to in the 1981, catches of anchovy and squid greatly increased (p < 0.05), while catches of Alaska / walleye pollock has been almost extinct over the past 30 years. As such, cold-water fish species decreased or disappeared, and their fishing ground was replaced by warm-water fish species. Conclusions: These findings indicate that fish species caught in offshore fisheries of Korea have changed due to climate change, especially warming. This suggests that the warming of the Korean Peninsula may have a significant impact on the supply of fishery products and food security to Koreans in the near future.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.4
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• pp.287-298
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• 2000

The charge of distance and the change of tack between paired boats were measured by ship's distance measuring system fixed MCS in the main boat and MS in the following boat. The operating depth of the anchovy boat seine was recorded and analysed by self memory temperature/depth sensor in order to compare the relationship between the distance between towing boats and geometry of the anchovy boat seine net. The results are as follow, (1) When distance between paired boat was 5m, the fishing net was spreaded down deeply and unstably in accordance with bag net and flapper may be help to pass out anchovy school. (2) When distance between paired boat was 100m, vertical opening of the net was gradually increased with higher slope of towing depth in the square, bosom and flapper. Therefore, fishing efficiency could be decreased by preventing the entering of anchovy due to unstable shape of the bag net. (3) When distance between paired boat was 200m, the geometry of the anchovy seine was stable condition with the end of bag net was up while flapper was down and it may cause bad effect in fishing efficiency. (4) When distance between paired boat was 300m, the shape from wing net to bag net was gradually slow down and stable enough as well as good shape in bag net and flapper. (5) The ship's distance measuring system could be used for measurement and accurate control of distance between paired boat in accordance of anchovy recordings by fish finder in order to get higher fishing efficiency in anchory boat seine operation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.1
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• pp.67-73
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• 1985

The relationship between the fishing grounds of Buse, Pseudosciaena crocea (Richardson), and oceanographic condition in the Yellow Sea and the East China Sea is studied on the basis of the data of the catches of stow net fishery (Fisheries Research and Development Agency, $1967{\sim}1979$) and the oceanographic observation data. The main fishing grounds of the Buse was concentrated in southwestern area of Cheju island and the best catch was in April. CPUE was less than 50 kg/haul in the most pare of fishing grounds, there-fore the conditions of fishing grounds generally were poor and coefficients of variance were also large. In the main fishing period, April, the fishing grounds were generally distributed in colder region of $8^{\circ}C$ through $10^{\circ}C$ isotherm at 50 m depth, than Yellow croaker and Gangdali which were distributed between $10^{\circ}C$ and $15^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.2
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• pp.208-217
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• 2021

This study described the fishing characteristics of Pacific herring Clupea pallasii and examined the relationship between its catch and sea temperature in Korean waters from 1970 to 2019. Although the herring catch in Korean waters stayed below 1,000 tons per year from the mid-1970s to mid-1980s, the catch in the winters in the East Sea of Korea started to increase markedly after 1987-1988, when the sea surface temperature (SST) seemed to shift to a warmer regime. Since the mid-2000s, overall, herring was caught throughout the year in the East Sea and eastern South Sea of Korea, and its catch significantly increased by around 30,000 tons per year. The main fishing grounds of herring in the poor fishing years until the mid-1980s were possibly formed in the western offshore of Korea, and subsequently the fishing grounds were distributed in the eastern coast of Korea. While the standardized catch per unit effort (CPUE) for two main fisheries of herring catch was significantly correlated with the herring catch since the 2000s, there was a gradual decline since the 2010s. The herring catch in the East Sea had significant positive correlations with SSTs, but that in the West Sea had a significant negative correlation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.4
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• pp.360-364
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• 1990

To testy time division scheme, we performed some experiments in a circular water tank(13m in diameter and 1m deep). A result of that is shown in figure 4. The 2-dimensional position of the pinger was calculated by the method of hyperbolic line of position calculation. The resolution of the time difference on the base line is 2.5cm. In experiments, the multiple pingers of a single frequency were distinguished and tracked successfully. When the experiment is carried out in the water tank, some multi-path pulses always occur. To delete it, several 10 ms of time delay is inserted onto the program after a group of the normal signals are received. Some normal pulses are not received by the time delay, however there is no problem, practically, for the distinction and the tracking of the pulse. In 2-dimensional positioning, the pinger position can be calculated with three hydrophones. However, if four hydrophones are available, the positioning accuracy will be higher than three hydrophones only by some techniques. Another good feature of the use of four hydrophones is that the positioning of the pinger is capable if a hydrophone fails in receiving them. We also tested this distinguishing method in the field using another type pingers(APPENDIXA).

• Korean Journal of Ichthyology
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• v.17 no.1
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• pp.64-72
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• 2005

The data for the present study were collected from the both-sides fyke net fishery in coastal Dolsan, Korea, from March 2003 to February 2004 A total of 2,402 individuals (432,42 kg) were collected and identified to 11 orders, 34 families, and 48 species. The most dominant order was the Perciformes, comprising 21 species in 15 families, followed by Scorpaeniformes, 8 species in 5 families, and Pleuronectiformes, 5 species in 3 families, These three orders constituted 67.9% of the total collected fish. The most dominant species, Acanthopagrus schlegeli, accounted for 279 individuals (20.26 kg), followed by Mugil cephalus with 187 individuals (99.61 kg), and Konosirus punctatus with 178 individuals (8.89 kg). The diversity index of the fish catches was 1.6823~2.9105 and was the highest in September 2003 and the lowest in December 2003. The evenness index was 0.6585~0.8872 it was the highest in August 2003 and the lowest in December 2003. The dominance index was 0.2000~0.6852, with the highest in December and the lowest in August 2003.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.4
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• pp.282-290
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• 1992

Based on surplus production models using fishery data for the last 20 years, a stock assessment was conducted for the small yellow croaker in Korean waters. The maximum sustainable yields (MSY) from the Schaefer and Fox models were estimated to be 37,000 metric tons (mt) and 33,450 mt. Zhang's model using time-series biomass with instantaneous coefficients of fishing mortality (F) and using time-series biomass and catch yielded MSY estimates of 45,328 mt and 40,160 mt, respectively. A yield-per-recruit analysis showed that the current yield per recruit of about 20g with F= 1.11 $yr^{-l}$, where the age at first capture $(t_c)$ is 0.604, was much lower than the maximum possible yield per recruit of 43g. Fixing $t_c$ at the current level and reducing fishing intensity (F) from 1.11 $yr^{-l}$ to 0.4 $yr^{-l}$ yielded only a small increase in predicted yield per recruit, from 20 to 25g. However, estimated yield per recruit increased to 43g by increasing $(t_c)$ from the current age (0.604) to age three with F fixed at the current level. This age at first capture corresponded to the optimal length which was obtained from the $F_{0.1}$ method. According to the analysis of stock recovery strategies employing the Zhang model, the optimum equilibrium biomass $(B^*_{MSY})$ which produces the maximum yield could be achieved after approximately five years at the lower fishing intensity (F=0.5).