The age and growth of the sandfish, Arctoscopus japonicus were investigated from samples of the eastern sea danish seine and gill net fishery in the East Sea of Korea from February, 2004 to December, 2007. Ages were determined from annuli in otoliths and annuli were formed between December and February once a year. Also, the main spawning period was estimated to be between December and January, thus rings were considered to be annual marks. For the relationship between fork length and total weight, a multiplicative error structure was assumed because variability in growth increased as a function of the length. The relationship between fork length and total weight were TW=0.0083FL3.01(R2=0.966) for female and TW=0.0079FL3.04(R2=0.969) for male. The variability in growth was constant as a function of age, revealing an additive error structure. The von Bertalanffy growth parameters estimated by a non-linear method were L∞=31.6cm, K=0.266/year, t0=-0.835 years for female and L∞=27.7cm, K=0.273/year, t0=-0.806 years for male. Growth at age between male and female had a significant difference(P〈0.001).

Patagonian toothfish(Dissostichus eleginoides) was investigated in the southeastern Atlantic Ocean during the period of 19 March to 7 July 2007 by commercial bottom longliners. The number of 116 hauls were carried out individually in this study area by two bottom longliners during 111 days. The total catches were 89,559kg(9.91kg/100hooks) and 66,758kg(7.38kg/100hooks), respectively. Most Patagonian toothfishes were caught on the 46-48˚S, 6-11˚E of southeastern Atlantic Ocean. Patagonian toothfish comprised 67.01-92.49%(by weight) of the catches in the southeastern Atlantic Ocean. No Antarctic toothfish (Dissostichus mawsoni) was caught during the surveys. Patagonian toothfish was found throughout the experimental area, but the density was considerably greater in the layer of 1,300-1,900m, where 49.88% of the fishes were caught. Smaller fishes were generally distributed to the shallow waters and larger fish were more frequently caught with the depth. Mean size of Patagonian toothfish increased with depth of capture. Accordingly economically profitable fishing activities for the Patagonian toothfish fishery requires an understanding of the size distribution of the Patagonian toothfish by depth.

Squid jigging fishery is very important in that there are about 1,000 jigging vessels more than 10 tonnage and about 5,000 ones less than 10 tonnage in Korea. But the cost of oil which is used to light fishing lamps, goes significantly up to almost one hundred million won for 50 tonnage vessels and forty million won in case of vessels less than 10 tonnage. This cost has almost taken 40% of total fishing costs. That is, the fishing business condition of squid jigging fishery is recently in the very difficult situation. As oil price increases, the business condition of the fishery gets worse and worse. Therefore it is very urgent to develop an economical fishing lamp, to solve this problem of fishery's business difficulty. This research aims at developing a fishing lamp for squid jigging fishery using the light emitting diode which has very excellent efficiency and durability. We made a water tank with 20 meters width which is a shape of raceway to research behavioral characteristics of Japanese flying squid to LED light, and made an experiment to investigate optimum wave of LED light to lure squid. The method is to establish LED lamps on both ends of water tank and to observe squid's behavior. Colors and wave lengths of LED lamps, used in experiment, are red(634nm), yellow(596nm), green(523nm), blue(454nm) and white(454nm+560nm). In experiment for attractive capability of LED lamp to squids, Japanese flying squid are highly attracted to blue lamp and white lamp. However, they are dispersed to red and yellow lamps. In addition, Japanese flying squid have moved and stayed in both dark ends of water tank. When compared intermittent lamp with continuous lamp, Japanese flying squid are highly attracted to intermittent lamp when intermittent interval is 0.25 second.

In order to develop the substitutive materials for natural baits of swimming crab pots, the attracting effects of swimming crab such as the preference of baits which were made of the by-products of marine and stock raising through the water tank experiments and fishing experiments. On the investigation of mean entrapped catch number to the pot by the baits after putting the 4 kinds of baits, mackerel(M), mackerel with grinded mackerel s internals(MMI), mackerel with tuna s internalsMMI) and makerel with grinded krill(MK) each in one pot by turns, MMI and MK were entrapped mean 3.9(13.0%) and they were a little more comparing to M, and MTI is least with mean 2.1(7.0%)(F=12.913, P 〈 0.05). Otherwise, on the preference investigation of swimming crabs by the baits after putting the 4 kinds of baits in the 4 pots each, M was entrapped mean 3.0(10%), but MMI, MTI and MK were mean 1.2(4.0%), 1.0(3.3%) and 1.5(5.0%) each and they were only 30-50% of M(F=13.398, P 〈 0.05). On the preference investigation of swimming crabs by the 5 kinds of baits, mackerel(M), and krill(K), manila clam(MC), pig s fat(PF) and chicken s head(CH) which were used in substitutive baits, M was entrapped mean 3.2(10.7%), but K was about 50% of catch of M with mean 1.6(5.3%), and MC, PF and CH were very few with mean 0.1-0.2(0.3-0.7%)(F=89.186, P 〈 0.05). On the preference investigation of swimming crabs by the pots which were put each the 3 kinds of baits, original krill(K), grinded krill with gluten and soybean oil cake(KGGS) and grinded krill with gluten, soybean oil cake and glycine(KGGSGL) in the blue fluorescent hexahedral plastic bait cages(BF), and which were put the mackerel(M) in the non-fluorescent hexahedral red plastic bait cage(RFN), it was entrapped mean 3.0(10.0%) in the pot which was put the mackerel in the RFN, and the same level in the pots which were put the K and KGGSGL in the BF, but it was mean 2.0(6.7%) in the pots which was put the KGGS in BF and it was decreased by 30% of catch comparing to RFN(F=3.750, P 〈 0.05). On the preference investigation of swimming crab by the pots which was put grinded tuna with gluten, soybean oil cake and glycine(TIGSGL) in the blue fluorescent hexahedral plastic bait cage(BF), and which was put mackerel(M) in the nonfluorescent hexahedral red plastic bait cage(RFN), it was entrapped mean 3.3(11.0%) in the pot which was put mackerel in RFN, and mean 2.7(9.0%) in the pot which was put TIGSGL in BF and it was about 15% less comparing to use bait M(t=1.387, P 〈 0.05). As a results of fishing experiments, a plan for enhancing catching efficiency of TIGSGL will be required because catching efficiency of TIGSGL, alternative bait, was half of fish catching efficiency of natural bait using mackerel. Fishing experiments were conducted 3 times using reinforced substitutive artificial bait that is reinforced attractive effect of TIGSGL and composed of tuna intestine, grinded mackerel, gluten, soybean cake, glycine and alanine(TIMGGSGLA). Catching efficiency of TIMGGSGLA was about 80% of that of natural bait made of mackerel.

In this study, the effect of slope length and angle at the entrance to fishing pots on the size of captured shrimp was examined to determine the optimal design of pots for use in Hokkaido, Japan. The purpose of the current study was to optimize the design of shrimp pots to allow greater control over the size of captured individuals for the purposes of shrimp resource management. Tank experiments were conducted to determine the optimal slope length and slope angle by analyzing the sizes of shrimp entering 10 model pots with combinations of five different slope lengths on slope angle of current shrimp pot, and five different angles on slope length of current shrimp pot. The results showed that, as the slope length of the pot increased, the size of individuals which entered the pot increased. In addition, as the slope angle was elevated in each of the five different slope angle treatments, the size of individuals entering was also increased.

Biodegradable polybutylene succinate(PBS) is an environment friendly plastics for fisheries, because it can mitigate the ghost fishing problem caused by gill-net and trap fisheries. To evaluate photodegradability of PBS monofilament in comparison with polyamide(PA) and polyethylene(PE) monofilament, these 3 types of monofilaments were spun and exposed to ultraviolet light(UV) of weather-ometer for 900 hours, and then their modification, crystal structure, strength, and extensibility were analysed. PBS monofilament did not show any crack and maintained its crystal structure after 900 hour exposure to UV whereas PE monofilament began showing cracks and structure modification after 600 hour exposure. Under UV exposure, the strength and extensibility decreased more rapidly in PBS than in PA and PE. We estimate that gill nets made of PBS monofilament can endure for about 1 year. The breaking strength and elongation decreased linearly with the exposure time for the 3 types of monofilaments. The derived regression equations of the residual tenacity(RT, kg/mm2) and the residual extensibility(RE, %) with the exposure time in year(Y) for each monofilament were; PBS : RT=48.598 - 8.6437Y(R2=0.93), RE=28.165 - 7.3233Y(R2=0.98), P A : RT=59.771 - 8.6437Y(R2=0.98), RE=32.198 - 5.2772Y(R2=0.92), P E : RT=60.898 - 5.6528Y(R2=0.98), RE=11.887 - 0.7188Y(R2=0.98).

Generally the side plate materials of FRP ship are composed of glass fiber and unsaturated polyester resin composites(GFRP composites). In this study, the effect of applied load and sliding speed on friction and wear characteristics of these materials were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials for SiC abrasive paper were determined experimentally. The cumulative wear volume showed a tendency to increase nonlinearly with increase of sliding distance and was dependent on applied load and sliding speed for these composites. The friction coefficient of GFRP composites was increased as applied load increased at same sliding speed in wear test. It was verified by SEM photograph of worn surface that major failure mechanisms were microfracture, deformation of resin, cutting and cracking.

Trawlers have to a sufficient towing force due to it's characteristics of the high performance. The newly constructed trawler with the conventional propellers shows the sufficient towing force, so that the propeller and engine are optimized. In the 1970s, many trawlers were imported from overseas by Korean fisheries industries. But the engine output degradation with year by year caused the trawlers to decrease the towing speed of the vessels. On the previous studies, the nozzle propeller had not so good efficiency with increasing of resistance in high-speed cruising operation over 15knots. But the trawling operation is just required the higher thrust and towing force, so that the nozzle propeller is very profitable for the it's effectiveness. A new nozzle propeller was designed for the 4,462G/T trawler, Dong-San, operated by Dongwon Industries Co., Ltd. to improve the towing speed, and the model tests were performed. The model ship and model propeller are preciously manufactured and used model tests in basin. The resistance test and propeller open water test were performed for the cases of the half and full loads. The required engine horse power and RPM were evaluated analytically by the speed-power curve, when the trawler was equipped with the nozzle propeller. The results of tests showed that the towing speed 4.85knots on the design load waterline requires the 200 engine RPM and 2,567ps in the delivered horsepower.

This paper describes on the consolidation of AIS and ARPA radar positions by comparing the AIS and ARPA radar information for the tracked ship targets using a PC-based ECDIS in Busan harbor, Korea. The information of AIS and ARPA radar target was acquired independently, and the tracking parameters such as ship's position, COG, SOG, gyro heading, rate of turn, CPA, TCPA, ship s name and MMSI etc. were displayed automatically on the chart of a PC-based ECDIS with radar overlay and ARPA tracking. The ARPA tracking information obtained from the observed radar images of the target ship was compared with the AIS information received from the same vessel to investigate the difference in the position and movement behavior between AIS and ARPA tracked target ships. For the ARPA radar and AIS targets to be consolidated, the differences in range, speed, course, bearing and distance between their targets were estimated to obtain a clear standards for the consolidation of ARPA radar and AIS targets. The average differences between their ranges, their speeds and their courses were 2.06% of the average range, -0.11 knots with the averaged SOG of 11.62 knots, and 0.02˚ with the averaged COG of 37.2˚, respectively. The average differences between their bearings and between their positions were -1.29˚ and 68.8m, respectively. From these results, we concluded that if the ROT, COG, SOG, and HDG informations are correct, the AIS system can be improved the prediction of a target ship's path and the OOW(Officer of Watch) s ability to anticipate a traffic situation more accurately.

This paper describes on the real-time tracking of ship's dynamic behavior by AIS information in the coastal waters. The AIS data was received at a land station by using the antenna of AIS receiver mounted on the rooftop of the laboratory, Pukyong National University (PKNU), Busan, Korea, and stored as a NMEA format of serial output sentence of VDM(VHF Data-Link Message) and displayed on the ENC(Electronic Navigational Chart) of a PC-based ECDIS. In this study, the AIS receiver was mainly used to obtain the dynamic information that is necessary to evaluate and track the movement situation of training ship "KAYA" of PKNU in the coastal waters. The change of position with time for the ship turning under the rudder angle of port 30˚ was correctly tracked with the turning circle of 940 m in diameter on the ENC of a PC-based ECDIS. Then, the dynamic information of the AIS system was updated every 6.29 seconds under the turning situation for the speed of 10.9 knots and every 21.65 seconds under the situation running at the speed of 11.05 knots on the straight line route of 155˚, respectively. In case of AIS target tracking in the inshore zone behind large topographical obstructions, such as mountain and apartment buildings, the update rate of dynamic information was irregularly changed by the existence of land obstacles. However, the position tracking by AIS information under the situation existing no sea obstructions was achieved in real or near real-time and the instant presentation of course alternations for the ship was correctly monitored by using a PC-based ECDIS. From these results, we concluded that the PC-based ECDIS technology and methodology combined with the AIS information can be easily extended and applied to the surveillance and management for the fishing operation of fishing vessels in the coastal zone and in the EEZ fishing grounds.

Costal regions in Korea often suffer severe damages due to wave-induced disasters, storm surge disasters and so on. therefore, many engineers and researchers have devoted their energy to prevent these costal disasters. The development of artificial reefs including sunken vessels is one of their remarkable achievements and various kind of these artificial upwelling structures have been designed and applied. However, the flow characteristics around a Tetrapod under the water has not been investigated experimentally. So in this article, in uniform flow of circulating water channel and some different velocities, PIV measurement has been conducted on the flow characteristics behind a Tetrapod. The results were analyzed on the flow characteristics of both cases of a Tetrapod. Therefore, it can be concluded that the both cases have its own distinctive flow characteristics behind the bluff body; Case A has an steep upstream flow pattern. On the contrary, Case B has an developed downstream flow pattern in the near wake of the Tetrapod. The velocity gradient at position x=150mm of Case-A appears gently up and down But, the velocity gradient at the same position of Case-B appears better highly up and down.

This study standardized catch per unit effort(CPUE) of the Korean longline fishery, which has been used to assess the status of stock as an index of abundance, for bigeye and yellowfin tunas in the Indian Ocean. The Generalized Linear Model(GLM) was used to analyze the fishery data, which were catch in number and effort data collected each month from 1971 to 2007 by 5 × 5 degree of latitude and longitude. Explanatory variables for the GLM analysis were year, month, fishing area, number of hooks between floats(HBF), and environment factors. The HBF was divided into three classes while the area was divided into eight subareas. Although sea surface temperature(SST) and southern oscillation index(SOI) were considered as environmental factors, only SST was used to build a model based on statistical significance. Standardized CPUE for yellowfin tuna showed a declining trend, while nominal CPUE for the species showed an increasing trend.

For environment-friendly fishery, the lead sinkers of octopus drift line were developed with the environmentfriendly sinker, and their characteristics and performance were investigated. To make the environmentfriendly sinker, the hydrate ceramic material was developed, and to increase the weight and strength, the iron power was added to it. The fishing hook was machine-made, and standardized, by using 60cm iron wire. For the manufacture of the sinker, the first, the mold was made, and then, hydrate ceramic material and water were quantitatively mixed. The mixture was poured into the mold prepared with a fishing hook already inserted, and had hardened for several hour, before it was taken out of the mold as a complete sinker. The sinkers were made in the 8 types ranging in weight from 150 to 500g, and their specific gravities were diverse from 2.871 to 6.637, which was 0.19 to 0.44 times lower than that of lead. The movement of the environment-friendly sinker by flume tank was possible in the weaker current speed than the similar lead sinker. In the coastal fishing grounds of Gangwon province, the comparison of catching efficiency was made between the improved fishing gears composed of the environment-friendly sinkers and artificial baits, and the current used fishing gears of lead sinkers and pig-fat baits. The result showed the tendency in which the improved fishing gears caught the bigger octopuses than the current used fishing gears. In the quantity and number of the fish catch per unit fishing gear, the improved fishing gear showed a little more catch than the current used fishing gear, regardless of the fishing area. However, the number of the improved fishing gears lost during fishing operation was similar to that of the current used fishing gears.

In order to develop the substitutive materials for natural baits of swimming crab pots, the fluorescent characteristics of the baits were analyzed, and the preference of fluorescent dyes were investigated by the mean entrapped catch number to the pots through the water tank experiments and fishing experiments. On the investigation of fluorescent characteristics by the 5 kinds of baits, mackerel, krill, manila clam, pig's fat and chicken's head which were used in substitutive baits for test in the UV long wave(365nm) area, it showed clear blue fluorescence in the skin of mackerel, shell of krill, manila clam and bill of chicken's head, and green fluorescence in the mackerel s muscle and internals, and yellow fluorescence in the pig's fat and chicken's head. On the investigation of fluorescent characteristics by the bait cages in the UV short wave(254nm) and long wave(365nm) area, it showed each green, red and blue fluorescence in the cylinderical or hexahedral red plastic bait cages which were painted each green, red and blue fluorescence dyes, but it showed yellowish green flourescence in the cylinderical or hexahedral red plastic bait cage which was painted yellow fluorescent dye. On the preference investigation of the fluorescent dyes of swimming crabs by the 5 kinds of the bait cages which were put the mackerel in the non-fluorescent red plastic cage(RFN), red, yellow, green and blue fluorescent plastic cages(RF, YF, GF, BF) each, nonfluorescent red plastic cage(RFN) was entrapped mean 2.0(6.7%), but blue fluorescent plastic cage(BF) was mean 5.0(16.7%) and it was more 2.5 times comparing to RFN, and red fluorescent cage(RF) was same level and green fluorescent cage(GF) was 50% of catch number comparing to RFN, and yellow fluorescent cage(YF) was entrapped nothing(F 46.324, P 〈 0.05). On the investigation of the entrapped catch number to the pots which were put the mackerel in the blue fluorescent hexahedral plastic cage(HP) and blue fluorescent silicon mackerel model cage(SM), HP was mean 3.4(11.3%) and it was a little more comparing to SM which was entrapped mean 3.2(10.7%)(t 0.775, P 〉 0.05). Fishing experiments on the preference investigation of swimming crabs by the pots which were put in the non-fluorescent red plastic cage(RFN) and blue fluorescent plastic cage(BF) were conducted 3 times. Mean catching number and weight of RFN were 71.7 ind.(18.3%) and 16.9kg(64.3%), and those of BF were 93.0 ind.(23.1%) and 19.8kg(64.5%), respectively.

Sea experiment for this study was carried out to develop a Trawl Escapement Net(TEN) using net material to improve the survival rate of undersized fishes that escaped from trawls in the Korean southern sea in May and November, 2005. Three kinds of Trawl Escapement Net(TEN) were examined to increase the escapement rate for fishes escaped from the TEN, and total catches in the codend and cover-net were investigated. The main catch species in the experimental fishing trials using a V shape TEN(A type) in May were Korean pomfret(Pampus echinogaster), slimy(Leiognathus nuchalis), gizzard shad(Konosirus punctatus), white croaker(Pennahia argentata) and smelt(Sillago sihama). In the experimental fishing trials using a V shape TEN with a protector for undersized fishes(B type) and a panel shape TEN with a protector(C type) in November, the main catch species were horse mackerel(Trachurus japonicus), sea pike (Sphyraena japonica), large-head hairtail(Trichiurus lepturus), kammal thryssa(Thryssa kammalensis), white croaker(Pennahia argentata), butterfish(Psenopsis anomala) and red gurnard(Lepidotrigla microptera). Most of large-sized fish species like Korean pomfret and Spanish mackerel could not escape through the TEN in the B type and C type. Catches of horse mackerel were highest in the experimental fishing of November and escapement rates for most fish species including horse mackerel were higher in the C type compared with B type.

In this study it will be discussed how to solve the problem of discomfort from rolling motion on the fishing boats. Most discomfort is caused by the short cycle of rolling due to the light weight of the boats. The light weight is due to the FRP material which dries a boat. A way to improve the feeling of boarding by using fish hold was researched. The experiment was done on experimental fishing boat made by FRP in Jeju. An existing fish hold was designed and manufactured through the rolling test and that was used for a marine experiment. The rolling condition of the U-tank boat ideally designed was compared to that of an existing fishing boat using the same conditions. The experiments were carried out two times on the stop engine in the outward Sehwa fishing port, which the experimental data had analysed for effects of rolling reduction to compare the U - tank with the of exiting fish hold. The results were confirmed that the U-boat tank in the roll period and GoM were more safe than the existing fish hold and the average amplitude and significant of rolling angles were decreased relatively.

Acoustic telemetry technique is one of useful tools to get behavioral information of the free-swimming fish. In this study, we conducted acoustic telemetry using coded acoustic transmitters to compare behavior characteristics between wild and cultured black seabream Acanthopagrus schlegeli, one of target species to promote resource in the marine ranching area. Two wild fish and five cultured fish were released in the marine ranching area after tagging surgically. Three of cultured fish were domesticated using the remote acoustic conditioning system for 3 weeks before being released. Two wild fish stayed at the released point for 2 hours and 9 days, respectively. One of wild fish was found about 10.8km away from the released point after 5 months. Two cultured fish stayed at the released point for 6 days and 75 days, respectively. One of acoustic conditioned fish stayed at the released point for 131 days and then was found about 10.1km away from the released point after 25 days. Others stayed at the released point during this study period(159 days).

This study was performed to estimate biomass and to provide management plan through population ecological characteristics, including growth parameters, survival rate, instantaneous coefficient of natural and fishing mortalities, and age at first capture of hen clam, Mactra chinensis, in the Dong-li self-regulatory community of Busan. The von Bertalanffy growth parameters estimated from a non-linear regression were SH∞=86.24mm, K=0.12/year, and = -1.37year. Survival rate(s) of the hen clam was 0.515. The instantaneous coefficients of natural mortality(M) was estimated to be 0.232/year and fishing mortality(F) 0.432/year for hen clam. The current biomass of the hen clam in the study area was estimated to be 713mt and the acceptable biological catch(ABC) was estimated under various harvest strategies based on F0.1 and F40%.

Estimation of the gear shape and cross section of sweep at mouth of a bottom trawl net was described and applied to the field experiments obtained with the Scanmar system. The shape of the trawl net from wingend to the beginning of codend was assumed to be part of an elliptic cone of which the cross section was ellipse, and that of the float rope be of form yf=afxbf. In case of a bottom trawl with warp 180m long, the radius of ellipse, the cross section of sweep at mouth, the eccentricity of the ellipse, the inclination angle of float rope and the contribution of the side panel to net height were estimated in accordance with towing speed. The horizontal radius of the upper ellipse increased with increasing towing speed, the eccentricity of it became slightly bigger as increasing the towing speed which meant the shape of it being flat. And the inclination angle of the float rope was about between 7 and 12 degrees in case of the above bottom trawl.

The fundamental data on the catch fluctuation in the rectangular set net according to the tide age were developed based on the catches recorded from the year 1986 to 2004 in the coastal waters of Hamdeok, Jeju. Total catch by the rectangular set net had a deep connection with the tide age. In particular, during increasing tide, total catch were reduced gradually from the neap tide to the high tide. As it turned out, the slope of total catch declined by degree and showed a correlation coefficient of determination of 0.76. On the contrary, in the case of decreasing tide, there was little sign of rise in total catch. In particular, large catch seemed to occur at the next tide to the neap tide. In the relation between the catch and the tide age, the level of the correlation coefficient chosen at p≤0.05 decreased in the order rabbitfish(-0.84) and horse mackerel(-0.71), while the significance of other dominant species were not selected.