The relationships among long-term variation in catches of Spanish mackerel (Scomberomorus niphonius) and main food organism such as common mackerel (Scomber japonicus), anchovy (Engraulis japonicus), and oceanic condition in Korean waters were analyzed using 40 years of time-series data from 1971－2010. In the 1990s, oceanic conditions around the Korean peninsula shifted to a warmer regime with higher SST (sea surface temperature). The total catch of Spanish mackerel in Korean waters increased dramatically since the early 2000s, and main fishing ground form into South Sea in winter season from December to January. From the results of correlation analysis, we found a significant relationship between the Spanish mackerel catch and environmental factor such as SST, common mackerel and anchovy catch in Korean waters.

This paper was concentrated on the distribution and the composition of lost fishing gear on the sea bed around yellow croaker fishing ground in the near sea of Jeju, Korea from April to October 2009 in order to improve the fishery environment. Recovering lost fishing gears was carried out total 10 times with a trawlnet along the isobath. As the result, it seems reasonable to conclude that the amount of lost fishing gear has a deep connection with the dip of the sea bed as well as the fishing gear scale, fishing ground and so on. The amount of recovered lost fishing gears were in order of gillnets, dragged gears, traps and ropes. In particular, traps were recovered almost every time within the survey area.

The forming of fishing ground and the population ecological characteristics of yellowtail, Seriola quinqueradiata, in the coastal waters off Gim-nyeong of Jeju Island were investigated. The stock of yellowtail, Seriola quinqueradiata, between Jeju Island and coastal areas of the East Sea is probably the same. Water temperature probably is a major factor for controlling distribution of yellowtails in deeper, offshore areas off Jeju Island. However, the major factor that determines aggregation of yellowtails in coastal areas of Jeju Island, especially off Gim-nyeong is probably strong tidal currents driven by distribution of yellowtails rather than hydrological conditions such as Yellowtails collected off Jeju Island were from 1 to 4yrs old and about 50% of them were 1-yr old, probably indicating overfishing. Jack mackerel was the major prey item for yellowtails off Gim-nyeong from October to March, suggesting concurrence of the two species.

The indirect target strength (TS) estimation method which uses the Kirchhoff ray mode model (KRM model) was discussed to apply for a biomass estimation in the water of mixed species. TS of 25 live scorpion fishes for 120kHz were measured by a tethered method and of others dominant 5 species in the marine ranching ground of Jeju coastal water including a scorpion fish were also estimated by KRM model. The measurement TS of scorpion fish well agreed with the theoretical values and the standard formula of scorpion fish was estimated as TS120kHz=20Log (L)-72.9 (r2=0.67). TScm values estimated on trial to each sample of dominant 5 species were from -69.3dB to -75.1dB at 120kHz and they were in the general range of swimbladdered fish. It was clarified that TS by KRM model can be used to estimate fish biomass estimation by increasing a sample number and is more effective under the condition that there is rare TS information for inhabiting species in mixed-species area.

This paper is to investigate the effect of the immersion time in the traditional hairtail hand line for developing the fishing methods and the fishing gear in the coast of jeju. The operating of 32 times was made with each different immersion time of hairtail hand line, and the relations between the catch and the immersion time were examined. As the result, targeted species rate was over 98% of total catch. From about 800 seconds after casting, the hooking rate was decreased and the bite loss rate was increased, it seems to be made by the decreasing factors of predators including the cutting of branch lines etc. In addition, it was supposed that the hooking rate and the bait loss rate had a deep connection with feeding time zone. The level of the correlation coefficient of the bait loss rate according to the immersion time was 0.54 at p≤0.01, in the case of the hooking rate, 0.59 was chosen after about 800 seconds. The hooking rate and the bait loss rate according to the hook number were not irrelevant to the fish school layer. Additionally, it was assumed that the bait loss rate was related to the depth of water.

This experimental study was carried out to obtain the base data for saving the man power in the fishing operation of largehead hairtail hand line by using the continuous type hand line system with a rotary device which could make a main line move automatically. In order to solve the twists and entangling on the main line happened during operating test, the resistance board was suspended at the end of the main line at sea. As the result, there were no problems of tangling and so on due to up and down moving of a main line. According to the control of a fixed angle of guide roller, it was possible to prevent the main line to be separated from a side roller and a guide roller. In addition, PVC tube between a guide roller and a side roller enabled a main line to be moved smoothly without any entanglement.

The underwater sound transmission system(USTS) was experimentally made to monitor the cetacean's appearance by telemetry, and then its system was tested to evaluate its performance from July to October, 2007 at the Kimnyeong berth and the dolphin's breeding ground of Pacific Land in Jeju island, respectively. The results showed that the sweep sound in the trial experiment and the whistle sound of bottlenose dolphin(Tursiops truncatus) were favorably received by telemetry. Therefore, we could confirm the USTS is able to monitor the cetacean's appearance in real time without direct observation at sea within effective range of code division multiple access(CDMA) communication method.

제주도 연안 정치망의 여름철 주 어획대상인 잿방어를 실험어로 하여, 음향을 이용한 어군행동 제어, 음향순치 등 바다목장 조성을 위한 어군의 관리, 사육, 어획기술에 이용할 기초자료를 제공할 목적으로 육상수조에서 수중 가청 저주파음과 전기충격을 이용하여 음향 학습 시킨 후, 주파수와 음압을 변화시켜가면서 잿방어의 섬전도를 도출 하여 심박간격의 변화로부터 청각문턱치, 청각임계비를 측정하였다. 자연환경소음에서 잿방어의 청각문턱치는 측정 주파수 80∼800 HZ의 수중 가청음을 모두 인식하였고, 측정 주파수 200∼500 HZ 에서 청각 감도가 양호하였으며, 측정 주파수 300 Hz에서 평균 음압 94.5 dB, 표준편차 4.5 dB로 가장 낮은 청각문턱치를 보였다. 평균 음압을 65 dB, 70 dB, 75 dB의 3단계로 변화시킨 백색잡음 방성으로 측정한 잿방어의 청각임계비는 측정 주파수 80, 100, 200, 300, 400, 500, 800 HZ에서 각각 평균 음압 45.9, 52.8, 42.5, 36.4, 38.6, 39.4, 44.4 dB이었다. 측정 주파수 300 HZ, 400 HZ 그리고 500 HZ 에서는 백색잡음 중에서 측정음을 식별하는 능력이 다른 측정 주파수에 비하여 우수했다. 잿방어가 주파수 300 HZ의 수중 가청음을 충분히 인식하기 위해서는 최저 100 dB 이상의 음압 강도가 펼요하며 환경 소음이 존재하는 환경에서는 소음 스펙트럼 음압 레벨보다 약 35 dB 이상 크게 방성할 펼요가 있다.

제주도 연안 정치망의 어획성능을 향상시키기 위한 어구구조개량과 조업방식의 생력화에 대한 기초자료를 제공할 목적으로 현재 제주도 연안정치망 어장에 부설하여 조업을 행하고 있는 각망어구와 낙망어구의 어획성능을 비교하기 위해서 두 어장의 3년(1997~1999년)간 어획량을 분석하였는데, 그 결과는 다음과 같다. 1. 1997~1999년까지의 3년간의 총어획량은 각망어구가 18.7톤 낙망어구가 36.5톤으로 낙망구의 어획량이 2배 정도 많았다. 2. 1997~1999년까지의 오징어, 전갱이, 독가시와 방어의 어획량은 전체적으로 각망어구보다 낙망어구의 어척량이 1.8배 정도 많았다. 3. CPUE는 각망어구에서는 전갱이가 10.01k 오징어가 20.5kg, 독가시치가 18.0kg 방어가 2.2kg이며 낙망어구에서는 전갱이가 57.5kg, 오징어가 30.0kg, 독가시치가 25.0kg, 방어가 4.7kg였는데 전반적으로 낙망어구의 CPUE가 높게 나타났다. 4. 유어율은 각망어구에서는 전갱이가 64%, 오징어가 79%, 독가시치가 39% 방어가 14%이고 낙망어구에서는 전갱이가 18%, 오징어가 85%, 독가시치가 40%, 방어가 14%로 전체적으로는 각망어구의 유어율이 높게 나타났으나 여기서의 어획량은 낙망어구가 높게 나타났다.

An underwater speaker was made of a moving coil driver unite of usual speaker, acryl-boards, polyester resin, rubber and castor oil and it's frequency characteristics was measured in range of 250~600Hz in air water tank and sea. The results of measurements are follows: 1. Transmitting and receiving frequency of measurement frequency were similar in air, water tank and sea. 2. The input and output wave forms of a manufactured speaker which is not water-proof in air were similar to each other in 300~450Hz, but other frequencies showed distorted wave forms. 3. The input and output wave forms of an underwater speaker in water thank and sea were similar to each other in 250~600Hz. But output wave forms showed combination waves with very low frequency. 4. Transmitting and receiving frequency wave forms and resisting pressure of an underwater speaker at 80m in the depth of water were in good condition. Therefore it can be possible to use it as an underwater speaker.

제주도 성산 연안 지역에 서식하는 오분자기의 생식주기를 조사하기 위하여 2006년 5월부터 2007년 4월까지 채집된 개체를 대상으로 생식소지수와 생식세포 발달단계, 황색 과립세포 출현양상과 생식상피의 형태변화를 조사하였다. 생식소지수(GI)의 월별 변화는 암컷과 수컷 개체 모두 유사한 경향을 보였다. 암컷 GI는 2006년 5월 에서 6~8월 으로 최대값을 보였고, 9월 으로 감소하였다가 10월 증가한 후 2007년 4월까지 낮은 값()을 유지하였다.