In order to replace sardine baits for octopus pot, an efficacy experiment to lure with alternative bait (fermented skate or chicken skin in artificial crab or northern clam) pots and sardine pot were conducted in a circular water tank. The soaking time of the sardine bait was divided into two categories: six days or less and seven days or more. The behavioral response of octopus to the artificial bait pots and sardine pot were investigated. In the comparison of the luring effects between pots with fermented skate inside artificial crab or northern clam and sardine pot, the pot with artificial crab + fermented skate had better results than the other pots in the section distribution (31.6%) and the number of times the pot was entered into (20.0%) (p > 0.05). In the comparison of the luring effects between pots with chicken skin inside artificial crab or northern clam and sardine pot, the pot with northern clam + chicken skin had better results than the other pots in the section distribution (22.6%) and number of times the pot was entered into (55.6%) (p < 0.05). The results were also better compared to those of pot with artificial crab + fermented skate. From these results, it seems that in the luring effect aspect, sardine bait can be replaced with artificial bait consisting of chicken skin inside northern clam.

This study investigated the luring effect of the sardine bait, which is used to catch octopus with pot, as the preliminary study for the development of alternative bait for octopus pot. The soaking time for bait was divided into “5 days or less” and “11 days or longer” The number of times octopus entered the pot with bait and the empty pot was investigated under dark adaptation and light adaptation processes and the distribution of tank section was investigated under light adaptation process. The case of “11 days or longer” sardine soaking time showed higher rate of distribution in the section of pot with bait compared to the case of “5 days or less” In the case of “5 days or less” soaking time, the number of times the octopus entered the pot with bait was similar to that it entered the pot without it even during dark adaptation and light adaptation. However, in the case of “11 days or longer”, the octopus entered the pot with bait more quickly than the pot without bait and more frequently during dark adaptation hours. There were cases where the octopus did not enter any pot. In the case of “5 days or less”, with less decomposition of baits, the octopus entered the empty pot more during light adaptation process, and it appeared that the pot was used as a hideout.

In this study, the entrapped number is investigated on the UV light with different illuminance to fluorescent bait cage for swimming crab in order to find the appropriate illuminance which has the best attraction effect of fluorescent bait cage for pots. In addition, preference to the light, arrival time and residence time at light area are compared and analyzed to fluorescent bait cage and non-fluorescent bait cage for American lobster at the UV light and ordinary light according to the illuminance condition. Pot with red non-fluorescent bait cage at the no lighting (<0.01lux), pot with blue fluorescent bait cage at the 20W UV lighting (0.16lux) and pot with blue fluorescent bait cage at the 30W UV lighting (0.22lux) were soaked for 6 hours and the entrapped number of swimming crab was examined. The mean entrapped number of swimming crab in pot with red non-fluorescent bait cage at the no lighting (<0.01lux) was 1.0, but the mean entrapped number of swimming crab in pot with blue fluorescent bait cages at the 20W UV lighting (0.16lux) and 30W UV lighting (0.22lux) were 1.4 and 0.4, respectively (P<0.05). The rate of preference to the blue fluorescent bait cage at the UV lighting shows 1.6-4.8 times higher than that of preference to the red non-fluorescent bait cage at the ordinary lighting. In addition, The rate of preference to the blue fluorescent bait cage at the UV lighting is higher when the illuminance of ordinary light is same as or is lower than that of UV light (P<0.05). However, the preference to the light depending on gender shows no significant difference (P>0.05). The arrival time to UV light area of lobster is shown as 1.2-2.4 times faster than that to ordinary light area. Generally, it is shown that arrival time to UV light area is faster than the arrival time to ordinary light area when the illuminance of ordinary light is the same as or lower than that of UV light (P<0.05). However, arrival time to the light area depending on gender shows no significant difference (P>0.05). The residence time at UV light area of lobster is 1.2-1.7 times longer than that at ordinary light area. The residence time depending on different illuminance of ordinary light and genders showed no significant difference (P>0.05).

The paper presents investigations on to which degree the sinking speed of longlines is influenced by type of bait, bait sinking orientations and anchor weights. The main aim of this study is to obtain further insight in the ocean current displacement phenomena in demersal longlining. The sinking speed is one of the main factors deciding the current displacement. In an ongoing project, sinking speed experiments with longlines with 6 kg and 10 kg anchor weights have been carried out in the Trondheim fjord. The longlines used in the first experiments were rigged without bait and hook. The results of these experiments with two different anchor weights have revealed only a slight difference in the sinking speed, except for the part near to the anchors, even though the sinking speed of longlines in general is supposed to be much influenced by the anchor weights. The reason for the obtained result is supposed to be that the experiments have been carried out at relative shallow waters. Further studies have included bait sinking experiments in the flume tank. The experiments showed that the drag coefficient of "fillet type (flat)" bait varied from 0.763 to 1.735, while it for "elliptic type" bait varied from 0.62 to 1.483. Other activities have included calculation of the sinking speed of longlines as a function of the established resistance coefficients of bait of various shape and size for commercial longlining. The calculated sinking speed of a longline with the fillet type bait was found to be 12.4 to 16.5% lower than for a longline without bait.

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.

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.

In order to evaluate the biodegradability of bait used in the pot for swimming crab, water tank experiments were conducted. Mackerel is the most commonly used natural form of bait to catch the swimming crabs, and therefore was used in this experiment for the biodegradability according to the manufacturing process of the bait. From the biodegradability test on chemical oxygen demand(COD), total nitrogen(T - N), total phosphorus(T - P), ammoniac nitrogen, nitrite nitrogen and nitrate nitrogen per unit weight of the bait based on the production rate and the accumulated amount of pollutants, it was concluded that the smaller the size of the mackerel pieces, the higher the production rate and accumulated amount of organic matter and nutrients which was unfavorable to water pollution. The amount of pollutants released from the intestine of the tuna was similar with that from the whole mackerel. For the operation period of 111 days, the accumulated concentrations of tested pollutants from the tuna which were 67.3 mgCOD/g d, 86.4 mgT N/g d, 3.1 mgT - P/g d, were almost half comparing with those from the mackerel which were 65.7 - 94.4 mgCOD/g d, 83.8 - 109.4 mgT - N/g d, 3.1 - 5.2 mgT - P/g d. The amount of pollutants released from the intestine of the tuna was slightly less than that from the mackerel that was cut into 8 pieces. but more than that from the mackerel which was not cut into pieces. Therefore, it can be concluded that the key factor in determining water pollution potential is not the kind of bait, but the processing or preparation method used.

The crayfish-shaped artificial bait for octopus drift line is manufactured, into which is made to insert ordinary bait. The effects of the artificial bait are confirmed through the analysis of octopus' behavior in the laboratory in comparison with the existing bait of pig-fat skin, and the investigation of the octopus catch on the sea, and in addition, the examination of the water quality in relation to the bait to be inserted into the artificial bait is done together. The artificial bait is red in color, 10.5cm in the length of the body, and 29g in weight. The octopus behavior in relation to the bait in the laboratory has shown a good result in which more than 30% of the octopuses rushed to the artificial bait. In the analysis of the octopus sitting time by the bait, the octopus stayed longer with the artificial bait(63.7%) than the pig-fat skin(25.1%). The octopus sitting time at the artificial bait inserted with frozen squid(48.8％, 44.6％) is shown to be longer than that of the pig-fat skin(36.9％) or boiled fish paste(21.2％). In the analysis of sitting frequency to the bait, the case of the artificial bait(total 17 times) was more than that of the pig-fat skin(total 3 times), and the case of the artificial bait with frozen squid attracted the octopuses more frequently than that of the pig-fat skin or the boiled fish paste. In the field experiment, the fishing boat A(Manseon-ho, 1.22tons) caught the total 93 octopuses, while the fishing boat B(Ilho-ho, 0.73tons) caught the total 154 octopuses, all of which weighed less than 9.0kg. In the comparison with the total catch, the case with the artificial bait was a little higher than that of the pig-fat skin(**p < 0.05). In the analysis of the water quality in relation to the baits, the COD showed the descending order of frozen squid(0.57mg/g), boiled fish paste(0.18mg/g), and pig-fat skin(0.10mg/g), and the case with frozen squid was the highest and the case of the pig-fat skin, lowest. The total phosphorus, like the COD, showed the highest in frozen squid(0.02mg/g), and in case of the total nitrogen, unlike the COD, the pig-fat skin was shown to be the highest(0.006mg/g).

멸치는 남해안에서는 여러 단계의 크기의 것이 혼획되는데, 가다랭이 미끼용으로는 채장 6-7m의 것이 알맞으므로, 이 크기의 것을 가급적 언중 확보하기 위해서는, 그 분포상을 조사하여 적정 자원이 가장 많이 출현하는 해역을 알 필요가 있다. 또, 멸치의 크기에 따라 상품가치도 크게 다르므로 멸치 어업을 합리적으로 운영하기 위해서나, 자원의 관리를 위해서도 채장 조사는 중요하다. 여기서는 멸치어업이 주로 이루어지는 7월부터 12월의 한국 동남 해역에 있어서의 멸치의 분포상에 관하여 조사한 것을 보고한다

한국 연안에서는 연간 5~8만m/t정도의 멸치가 어획되고 있으나 주 어장은 경남 일원을 중심으로 남해안이다. 따라서 남해안의 어황변동을 예보할 수 있으면서 어업경영의 합리화에 크게 이바지 할 수 있을 것이고, 그에 따라 황멸치의 수급 계획 수립에도 크게 도움이 될 것이다. 여기서 먼저 1971~77년 7년간의 수온, 부유생물, 강수량과 열수지를 조사, 계산하고 그 해 봄철의 강수량을 조사하면 그 해의해황이 예측될 수 있고 그에 따라 멸치의 어황도 예보할 수 있을 것으로 기대된다

재래식 권현망의 천장망을 제거하고 옆판 위 언저리에 뜸을 장치한 어구에 의하여 활멸치의 어획을 시험하고, 동시에 이렇게 어획한 멸치를 버팀대를 써서 축양조를 예인하는 방법으로 축양 시험을 실시한 결과 대략 다음과 같은 결론을 얻었다. 축양개시 15일후의 생잔률은 최고 약 71%여서 다른 어구. 어법에 의한 생잔률 보다는 낮지마는, 권현먕 어구 자체가 한국의 멸치 어업에서는 가장 보편화된 어구이므로, 2차적으로 활멸치를 어획하는데는 충분한 실용성이 있다고 보아진다.

朴.李등 (1972)이 축양 시험을 할 때에는 축양조 이외에 소형의 예인조를 따로 썼으나, 예인조에서 축양조로 이송이 번거로우므로 업계에서는 축양조를 바로 예인하는 방법이 쓰이고 있다. 그러나, 축양조를 바로 예인하면 앞면의 망지가 뒤로 밀려서 축양조 내부의 용적이 작아지고, 또 예인중 축양조의 속도가 갑자기 느려지면 멸치는 유영 관성으로 말미암아 뒤로 밀린 망지 위로 올라가서, 비늘이 벗겨져서 폐사율이 높아진다. 이를 개량하기 위해 먼저 $\frac{1}{15}$크기의 모형 축양조를 만들어서, 회류수조에서 4가지 방식으로 예인시험을 실시하고, 그 중 합리적이라고 생각되는 2가지 방식을 다시 해상에서 실물시험을 실시하여, 실용상의 문제점을 규명함과 동시에, 축양조의 예인속도는 빠르게 하면서도 축양조 내부의 유속을 느리게 하는 방법도 고안했다