• Korean Journal of Ichthyology
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• v.20 no.2
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• pp.105-111
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• 2008

A pelagic tuna longline research cruise in the eastern and central Pacific Ocean from September to October of 2006 was conducted to compare catch rates with the use of different hook type and bait combinations. Traditional tuna hooks (J 4) and three circle hook types (C15, C16, C18), along with five bait types (chub mackerel (CM), jack mackerel (JM), milkfish (MF), sardine (SD), and squid (SQ)) and hook number as a proxy for hook depth were evaluated for their effect on bigeye tuna catch rates (fish per 1,000 hooks) using Generalized Linear Models (GLMs). Results from 28 sets indicated significant differences in bigeye catch rates between individual longline sets and hook number. The GLM explained 33% of the deviance in bigeye catch rates with these two factors. An alternative model formulation included bait type which had a small effect (explaining 2.7% of the deviance) on catch rates. Hook type had a negligible and non-significant effect in the GLMs. These results indicate that all of the hooks and baits tested are equally effective at catching bigeye tuna and that hook number (depth) was the paramount operational factor in explaining bigeye tuna catch rates.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.3
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• pp.240-246
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• 1995

The responses of red tile fish, Branchiostegus Japonicus to a longline gear were examined in an experimental tank using two video cameras, in order to know hooking mechanism and improve longline hook. In attraction stage, the fish swim to upstream direction slowly just above the bottom toward the baited hook. The majority of the fish then biting the bait incompletely, after the biting, the fish made a backward swimming with low intense, and the bait was usually spitting out when snood was stretched. In most case, hooking took place at the moment the fish made jerk or rush after the bait wallowed. The behaviour sequence closely related to hooking are chewing and jerking or chewing and rushing. According to the field experiments, the tested hooks of long shank show very low catching efficiency compared to the traditional hook with short shank, and the hooked position of the traditional hooks were oesophagus or stomach but the tested hooks were mouth in the most cases. For catching efficiency, desirable hook shape were inferenced inner-curved point and short shank because its ease to swallow. The shape and demensions of a porposed hook were determined in consideration of mechanized gear handling and hooking performance.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.1
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• pp.1-8
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• 2004

The single line hook fishery for giant pacific octopus, Parotopus dofleini is one of the important in coastal Kangwon-do of Korea, where was caught an average of 4,000 ton during the period of 1996~2000. The fishing gear is consisted of a single buoy line, a buoy and a hook. In this study, the responses of giant pacific octopus to single line hook gear were examined in an experimental tank using a video camera in order to know hooking mechanism and improve hook. Giant pacific octopus tend to envelop the bait with their arms by rush or slowly swimming towards it. When they rush to the bait, they show much feeding behaviour as withdrawing after enveloping the bait using two arms. But when they approach with slowly swimming to bait, they show feeding behaviour as stopping after enveloping the bait using one arm. and then, the highly hooking rate appeared more often in the case of latter then former. The average feeding time on a sardine, giant pacific octopus and pork fat showed the range of 1 to 30 min, 10 to 50 min, and 50 min to over 1 hour, respectively. This indicates that it takes longer time for giant pacific octopus to eat the tough meat than the soft meat. The performance concerned with hooking showed that the 'B' type hook with a short shank was more favorable than the 'A' type hook with a long shank. However, the 'A' type hook has the advantage of easy dropping out caught octopus, compared to the 'B' type.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.75-76
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• 2000

연승은 설치방법에 따라서 부연승과 저연승, 그리고 입연승으로 나누고 있고, 저연승은 주로 저층성어류를 대상으로 하여 양끝에서 닻으로 고정을 하며 어구의 중간에도 적당한 간격으로 추를 달아서 낚시는 원칙적으로 땅에 닿도록 하고 있다. 그러나, 어종에 따라서 눈의 구조와 물체를 분별하는 능력이 서로 다르고, 이로 인해서 낚시에 매달린 미끼를 쉽게 알아볼 수 있는 방향이 또한 다르다. 즉, 시축(Visual axis)에 따라서 고기가 미끼를 습격하는 방향이 대체로 정해진다고 볼 수 있다. (중략)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.2
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• pp.106-113
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• 1987

The Alaska pollack longline operations, which consist of baiting, shooting, hauling and arrangement of hooks, are dependant on manual labour up to the present. The automation against this traditional way is necessary to eliminate the manual operations and to reduce crew. We have developed a prototype longline system suitable for Alaska pollack longline gear, which is composed of an automatic baiting machine, an automatic line hauler, a hook cleaner and storage rails. The automatic bailing machine driven by hydraulic power is precise baiting method controlled sequentially, and the automatic line hauler is to haul up the mainline by means of hydraulic power and at the same time to split every hook and to carry it onto storage rail automatically. A series functioning tests on shooting and hauling apparatus were carried out in the laboratory and at sea. The results obtained are as follows ; 1. As for the baiting machine, the exciting time of solenoid which operates a directional valve, bait feeding and cutting time, is shortened according to the increase of pressure, and also, after cutting the bait, the over-rotated angle of the blade increased in accordance with the increase of pressure. 2. The baiting efficiency is about $90\%$ when using sand lance (Hypoptychus dybowskii), and the most proper pressure of the hydraulic circuit in feeding and cutting the bait is between $13\;kgf/cm^2\;and\;20\;kgf/cm^2$. 3. The hook splitting rate of the automatic line hauler is about $95.5\%$ regardless of hauling speed and materials of snood. 4. The case of unseparating hook is appeared when the snood gets entangled or the hook is sticked in the mainline.

• Proceedings of the Korean Aquaculture Society Conference
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• 2006.05a
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• pp.29-30
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• 2006

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.4
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• pp.305-317
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• 2003

Underwater shape and hook depth in tuna longline gear are important factors to decide fishing performance. It also should be considered that management and analysis of hooked rate data from hooked fish species and sizes, and each fishing would be used as a reference data in the future fishing. In this research, after analyzing underwater shape of tuna longline gear by current direction and speed using simulation, experiments were executed in flume tank to verify accuracy of the analysis. Also using the depth of each hook from the simulation, a database system was setup to process the data of bait and hooked fish species. The results were as follows；1. When the attack angle and the shortening rate are fixed, a decrease of the hook depth is proportion to an increase of current speed. 2. When the shortening rate and current speed are fixed, a decrease of hook depth is proportion to an increase of attack angle. 3. When the attack angle and velocity of flow are fixed, a decrease of hook depth is proportion to an increase of shortening rate 4. As a result of comparison between the underwater shape by simulation and that by model gear, the result of the simulation was very close to that of model gear within $$ {\pm}3%$$ 3% error range. 5. In this research, hooked rate database system using hook depth of simulation can analyze the species and size of fish by the parameter; bait. hook depth, so It could be helpful to manage and analyze the hooked data on the field.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.4
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• pp.312-316
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• 1982

With an object to obtain an indication on the efficiency of the saury baits for tuna longline, frequencies of the saury heads found in the tuna stomachs were analysed by the equations developed from tile binomial distribution. Four factors were introduced into the equations : The hooking rate, p; rate of not being hooked q; rate of the effective baits retained in the stomachs of the captured tuna r; and the rate of tile previously taken baits retained in the tuna stomachs, t. The best estimates of $\frac{p}{p+q^t}$ and r are empirically obtained as follows. Yellowfin tuna: $\frac{p}{p+q^t}$=0.789, r=0.598 Bigeye tuna: $\frac{p}{p+q^t}$=0.810 r=0.608, Albacore tun : $\frac{p}{p+q^t}$=0.838, r=0.621.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.4
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• pp.317-322
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• 1982

The biting behaviors of tuna were studied based on the remains of saury (Cololabis saira), which was used as bait, in the stomach contents of tuna. The saury remains were classified into four segmental groups (A-segment: Whole fish; B-segment: anterior partion with head: C-segment: middlepart without both head and tail: D-segment : posterior part without head). The tuna stomachs were independently named and grouped into three subsamples according to bait segments remaining in the stomach. The subsamples have the extra number of the stomach-naming segments and the distributions of the bait tegments are biased from tile random distribution. The distribution of the bait segments except the extra segments are hypothetically assumed to be random, and was subjected to the chi-square test of significance. The inferred conclusions are as follows:1. Most of the tuna having the B-segment had previously taken the C and/or D-segment. 2. The catchability of the yellowfin tuna having the B-segment seems higher than that of the fish having the A-segment in the stomach. 3. Tuna which had two or more bait heads should have taken the extra bait heads without being hooked detaching the head from the hook by biting the Posterior porting of tile bait.

• Journal of Aquaculture
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• v.20 no.2
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• pp.90-95
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• 2007

Artificially-produced juvenile black sea bream, Acanthopagrus schlegeli (total length $10.4{\pm}1.1\;cm$, body weight $18.7{\pm}3.4\;g$) were released into the Gamak Bay in Korea. And their initial feeding habits and body compositions were compared with those of cultured fish (CUL) for a period of one month after release. The released black sea bream commenced feeding on the 1st day after release, and predation rate was more than 80% during the sampling period. The stomach content of fish was composed of mainly fishing bait and krill in fish sampled on 15th days after release; however, its content changed to the natural organisms such as algae and small crustaceans when the fish was sampled on 20th days after release. Crude lipid content of carcass of fish in the sampling station A (SA) were lower than that of fish in the initial, sampling station B (SB) and CUL for the 5th and 10th days after release. Carcass n-3 HUFA composition, total amino acid and essential amino acid contents of released fish showed high trend compared to that of cultured fish in 30th days after release. The released fish have the ability to adjust their feeding habits and biochemical metabolism to the natural environment within a short period even though they showed preference to artificial feed in the early days after release.