• Korean Journal of Ichthyology
• /
• v.23 no.3
• /
• pp.206-216
• /
• 2011

To investigate seasonal and yearly variation of fishes composition in Yeoja Bay of Korea, fisheries survey were carried out using beam trawl from 2006 to 2009. A total of 44 fish species were collected. The major dominant species were Pennahia argentatus, Thryssa adelae, Thryssa kammalensis and Cynoglossus joyneri, which were occupied over 63% total individuals, and 50% of wet weight. The diversity index (H') was about 1.62 (1.46~1.77) by seasons, and seasons of similarity by fishes were divided into two groups, which were March with December and June with September. ANOVA test showed that there were not significant difference between individuals and catch weight (kg) per unit area (km$^2$) by year and season, except for catch weight per unit area by season.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.55 no.4
• /
• pp.303-309
• /
• 2019

This study identified the characteristics of squid jig in korea waters by investigating the effect of color and luminous performance of squid jig on the catch of squid and experimenting the result of jig according to green jig or white jig, and whether using luminous or not were tested in the sea to improve the jig of squid jigging. For this purpose, a total of 13 sea experiments were conducted using T/S No. 2 Galmaegi. As a result, 341 squids were caught. Among them, 221 squids were caught by green jig (64.8%), 64 squids were caught by white jig (18.8%), 41 squids were caught by green luminous jig (13.8%), and nine squids were caught by white luminous jig (2.6%). The green jig commonly used in jigging vessel was most effective, and luminous jig was less effective than that non-luminous jig. The squids caught were Japanese flying squid (Todarodes pacificus), swordtip squid (Loligo edulis) and spear squid (Loligo bleekeri), and no significant characteristics were found according to the color of jig and the presence of luminous.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.50 no.3
• /
• pp.342-350
• /
• 2014

An active stimulating device, such as a fluttering net or canvas attached to the end of a cod end generating a shaking motion, could help to encourage the escape of juvenile fish positioned passively near the net. Field fishing trials using a shrimp beam trawl were carried out to examine the effect on the reduction of juvenile fish or other discard catch by generating a shaking movement of the cod end using an unbiased cap-like round canvas. The mean period of the shaking motion with the round canvas was ~14 s, and the mean amplitude was 0.4 m as measured by peak event analysis and the global wavelet method. The bycatch of juvenile fish in 14 trials decreased by ~30% and by ~25% using a steady cod end for the total bycatch using a shaking cod end in the shrimp beam trawl, while the marketing catch was similar between steady and shaking cod ends. There was no difference in the body size of the shrimp or fish and species composition between the steady and shaking cod ends. Above results demonstrate a new method for bycatch reduction using an active stimulating device, although more detailed studies are needed.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.5
• /
• pp.51-57
• /
• 2011

Parametric studies based on analysis of lubrication system of a four cylinder gasoline engine are illustrated system in this paper. In development process of engine lubrication system, parts of failure cases are related with oil pull over and oil churning phenomenon. The crankcase & head system pressure by oil churning phenomenon are gradual increased. It cause oil pull over phenomenon at engine breather line and oil over-consumption. In order to improve oil reduction and oil pull over phenomenon are also considered in the developing state. For this study, the characteristics of engine lubrication system are measured at various tilting angle and drain hole sizes. In addition, the oil flow & oil quantity are tested by blow by meter and catch jar. Results are presented to stabilize the oil supply system at sever driving condition. The data from present study are available for the engine lubrication system.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.38 no.3
• /
• pp.202-208
• /
• 2002

Test fishing was carried out utilizing a coastal pot-fishing boat from IS March to 7 April 2002 and the results obtained are summarized as follows ; 1. Mean catches(Number of sea eels) according to the soak time of 3 hours, 6 hours and 12 hours were 44.6, 60.0 and 83.3, and CPUE(Number of catch / 10pots·hour) were 2.5, 1.7 and 1.1 respectively 2. Catch difference between over 24 hours and 48 hours was 11.3% and 3.3% between over 48 hours and 72 hours. 3. In the test fishing, by-catches were so low(1.5∼3%) until 12 hours of soaking time passed By-catches were increased according to the soaking time addition on the over 24 hours of soaking time. The bait effect for sea-eel seems to be diminished as soon as the casting started and there was big difference in proportion to bait size and freshness.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.22 no.5
• /
• pp.294-305
• /
• 1989

Basedon statistical data of pomfret (Pampus spp.) catches by the stow net during $1970\~1985$, the distribution and migration of pomfrets and fishing conditions were investigated in relation to oceanographic conditions, in the East China Sea and the Yellow Sea. The main fishing grounds of Pomfrets were formed around the Great Yangtze Sand Bank which locates between the Cheju Island and the mouth of the Yangtze River. Its area occupied only 11 percent of all fishing grounds, and about 70 percent of total catch was found there. The coefficient of variation(CV) in catch was below 0.01 in the whole fishing grounds and that of tile main fishing grounds (14 fishing areas) was $0.001\~0.003$. This area was indicated markedly by the inflow of Yellow Sea Warm Current from spring to autumn, and this mixing area which formed the oceanic front among the China Continental Shelf Water, the Yellow Sea Bottom Cold Water and the Tsushima Warm Current. The pomfrets migrates to south-north according to the expansion and contraction of the Tsushima Warm Current including the Yellow Sea Warm Current and the Yellow Sea Bottom Cold Water. Therefore, it migrates to north of the Yellow Sea in summer and to southern part of the East China Sea in winter. The most frequent range of the water type for high catch was $10\~12^{\circ}C$ in temperature and $32.4\~33.4\%_{circ}$ in salinity. The ranges was occupied more than 70 percent of total catch on fishing season. The frequency range of the water type was not different between the abundant fishing periods and the poor fishing periods in terms of the maximum catches.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.34 no.6
• /
• pp.624-631
• /
• 2001

The relationship between the catch of squid, Todarodes pacificus, according to the jigging depth and underwater illumination by fishing lamps was investigated during nighttime operations off-Tusima Islands in November 1994 and off-Oki Islands in November 1995. We used echo sounder to observe the distribution of squid. Echo images on the echo sounder showed the distribution of squid at the water layer of 50 meter depth at the beginning of jigging operation. After the time elapsed, a continuous dense image had moved to the layer of 60-80 meters jigging depth. A larger number of squid were caught by jigging machines set at a lowest depth of 90 meters, when it compared with machines set at a 60 meters. However, Catch increased around 60 meters jigging depth, when fishing lamps output were switched to 24 kW halogen lights:.The underwater illumination, under the each light power of fishing lamps of squid jigging boat was continuously measured with an underwater illuminometer. Values of the underwater illumination, when schools were distributed from 60 to 80 meters, ranged from $3.0\times10^{-2}lx\;to\;3.4\times10^{-3}lx$ in average at $80\~360$ kW fishing lamps output of squid jigging boat.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.7
• /
• pp.909-917
• /
• 2017

In this study, we investigated the relationship between catches of yellowtail and water temperature at the set net fisheries of Gyeongsangbuk-do (Gyeongbuk) and Gangwon-do (Gangwon) off the east coast of Korea from May-November, 1980-2010. We also analyzed the water temperature and fluctuation of catches during the northward moving period (May-August) and southward moving period (September-November) using NOAA satellite images. Although the total catches fluctuated year by year, catches increased during the southward moving period when the water alongside the coast warmed. Yellowtail catches during the southward period in fall were higher than those during the northward period in spring or summer. The catch when the water temperature decreased was larger in Gyeongbuk than in Gangwon for all periods However, the catch when the water temperature increased was much larger in Gangwon than in Gyeongbuk. This indicates that high summer temperatures (> $25^{\circ}C$) affected the coast of Gangwon, with high water temperature ($20^{\circ}C$) maintained in the region during fall. Therefore, the increased catch in Gangwon was due to longer yellowtail presence caused by increased water temperature.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.48 no.1
• /
• pp.10-19
• /
• 2012

The mesh selectivity of a drift net for yellow croaker (Larimichthys polyactis) was examined in field experiments with six different net mesh size (40, 45, 50, 55, 60 and 65mm) from April to December, 2008 in the coastal areas of Jeollanam-do in Korea. The total catch of 6,748 consisted of yellow croaker (n=6,310; 89.1% of total catch), common mackerel (n=158; 5.6%) and other species (n=280; 9.6%). The selectivity curve for yellow croaker was fit by the models of selectivity curve in SELECT method. The optimal mesh size for 50% retention for minimum landing size (191mm) of yellow croaker was estimated as 49.6mm-51mm by selectivity curves. And the bi-normal model for the selectivity curve was found to fit the data best.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.35 no.3
• /
• pp.267-276
• /
• 1999

In order to investigate the properties in distribution and movement of anchovy school catches by the lift net in the Kamak bay and their relation to the environmental factors, i.e., the water temperature and the salinity were observed form June to August in 1997 and compared with the catch of anchovy by the lift net. The results obtained are summarized as follows;1) The water temperature and salinity ranged form 20.0 to $27.0^{\circ}C\;and\;from\;31.2\;to\;33.8\texperthousand$, respectively. The water temperature and salinity at the fishing points ranged form 19.7 to $27.2^{\circ}C\;and,\;from\;30.5\;to\;33.8^{\circ}C$ respectively.2) The water temperature influenced remarkably on the distribution and movement of anchovy school. But the salinity influenced little on the distribution and movement. 3) The catch of anchovy was highest on July, poor second on August, and lowest on June. Anchovy school can be presurmed, they are come from north of bay, visited and distributed through east of bay at the middle of June. Moreover, they spreaded in all bay. Then gradually, when July arrive, they go to the south th nearest the coasts, and they are outflow through the south entrance of bay at the end of August.