• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.4
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• pp.210-216
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• 2006

The circle hook experiments were conducted to compare the catch rates of target and bycatch species between J hook and circle hooks in the tuna longline fishery of the eastern Pacific Ocean between $1^{\circ}48'S-7^{\circ}00'S\;and\;142^{\circ}00'-149^{\circ}13'W$ from July 15 to August 12, 2005. In the target species group no significant differences among 3 types hook, between size 4.0 traditional tuna hooks(J-4) and size 15 circle hooks(C15), and between C15 and size 18 circle hooks(C18) were revealed, but significant differences were found between J-4 and C18. In the bycatch species group significant differences were found among 3 types hook, between J 4 and C15, and between J-4 and C18, but no significant differences were revealed between C15 and C18. Large circle hook(C18) had the lowest catch rate for tunas and for other fishes, and the small circle hook(C15) had lowest rate for billfishes and sharks. The length distributions for bigeye tuna are very similar for the 3 hook types. There were very slight differences in length size between hook types in the bycatch species.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.4
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• pp.344-355
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• 2011

We conducted experiments to compare the catch rate of bigeye tuna and yellowfin tuna between circle hooks and straight shank hook in the Korean tuna longline fishery at the eastern and central Pacific Ocean from 2005 to 2007. We analyzed difference of fork length, survival and hooking location between a circle hook and a straight shank hook for both tunas, respectively. There was no difference in the mean fork length size of yellowfin tuna caught on the two type of hook but bigeye tuna was significant. In case of survival, there was no difference between two hook type, but the difference of hooking location was significant for both species. We also analyzed to find determinants of both tunas catch rate using generalized linear models (GLMs) which were used latitude, longitude, year, month, depth, hook type, bait type and so on as independent variables. Spatial factors, latitude and longitude, and temporal factors, year and month, affected catch rate of bigeye tuna and yellowfin tuna. And also, depth such as a marine environment factor was influenced on catch rate.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.313-318
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• 1999

This study is aim to evaluate of the flexure toughness of fiber reinforced concrete with ring type steel fiber. The experiment proceeding ASTM C 78 is performed to make a comparision between the ring type flber and the double-hook type fiber which is recently come in to use. The size of the test specimen is 10$\times$10$\times$35mm and the flexture test is proceeded by third-point loading method. The test lasts until 2mm deflection and the loading speed is 0.01mm/min by deflection control. From the experimental results, the specimens with ring type fiber of 30kg/㎥ and 30mm diameter of ring circle show much higher toughness indices than those of the double-hook type fiber of 30kg/㎥ and 30mm long.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.2
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• pp.157-164
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• 2009

The National Fisheries Research and Development Institute (NFRDI) conducted a circle hook experiment to compare the catch rates of target and bycatch species between J hook and circle hooks in the tuna longline fishery of the Eastern Pacific Ocean, which is located between $9^{\circ}13'S-1^{\circ}36'N$ and $126^{\circ}00'-138^{\circ}21'W$. Sampling was conducted from September 20 to October 23, in 2006. In this survey, we collected shark data to obtain the ratio of fin weight to body weight of sharks. Overall, 413 sharks belonging to 9 species were caught on 62,464 hooks. The total weight of the sharks caught was 11,093 kg. The ratio of wet fin weight to body round weight of sharks by species ranged from 3.7% to 7.7%, while the mean was 5.4%. The total ratio of wet fin weight to the dry fin weight of sharks ranged 0.38 to 0.70 and the mean value was 0.53. The ratio of dry fin weight to the body round weight of the sharks was estimated to be 2.86%.

• Fisheries and Aquatic Sciences
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• v.25 no.12
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• pp.589-600
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• 2022

Longline fishery targeting tunas and tuna-like species is known to produce a significant amount of catch not only for the target species, but also for ecologically related species like sharks, marine turtles, sea birds and marine mammals. Recognizing this seriousness, tuna related regional fisheries management organizations (t-RFMOs) have established conservation and management measures (CMMs) to reduce bycatch and/or interaction with ecosystem vulnerable species including sea turtles and are obliged to implement bycatch mitigation measures and guidelines on safe release to their member countries. Along with development and strengthening of those measures, various case studies have been conducting to verify the effectiveness of bycatch mitigation for ecologically related species. This study examines the background and progress on developing CMMs of t-RFMOs and regulation programs of the United States related to sea turtles, which have recently become one of the main issues, and reviews case studies on sea turtle bycatch mitigation measures to find out the effectiveness of reducing bycatch rate and impacts to the fisheries. In order to respond the consultation process on certification determination with the United States, it was confirmed the current status of implementation on related measures conducted by Korean tuna longline fishery based on scientific observer data and survey for captains. Even though all Korean tuna longline fleets belong to the deep-set longline fishery (100-300m), which is not subject to the obligation of those mitigation measures, they are voluntarily implementing both measures, use of circle hook and whole finfish bait, regardless of which RFMO's Convention area they operate. And the national regulatory and management programs for sea turtle bycatch prevention adopted by Republic of Korea seems to be comparable in effectiveness to that of the United Stated. However, Korea needs to take preemptive measures in establishing sustainable fisheries, including the protection of the marine ecosystem and environment, as stronger requests are anticipated to be made by the international community on this matter.

• Korean Journal of Microbiology
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• v.43 no.4
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• pp.243-249
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• 2007

The centromere is a highly differentiated structure of the chromosome that fulfills a multitude of essential mitotic and meiotic functions. Alphoid DNA (${\alpha}$-satellite) is the most abundant family of repeated DNA found at the centromere of all human chromosomes, and chromosomes of primates in general. The most important parts in the development of Human Artificial Chromosomes (HACs), are the isolation and maintenance of stability of centromeric region. For isolation of this region, we could use the targeting hook with alphoid DNA repeat and cloned by Transformation-Associated Recombination (TAR) cloning technique in yeast Saccharomyces cerevisiae. The method includes rolling-circle amplification (RCA) of repeats in vitro to 5 kb-length and elongation of the RCA products by homologous recombination in yeast. Four types of $35\;kb{\sim}50\;kb$ of centromeric DNA repeat arrays (2, 4, 5, 6 mer) are used to examine the stability of repeats in homologous recombination mutant strains (rad51, rad52, and rad54). Following the transformation into wild type, rad51 and rad54 mutant strains, there were frequent changes in inserted size. A rad52 mutant strain showed extremely low transformation frequency, but increased stability of centromeric DNA repeat arrays at least 3 times higher than other strains. Based on these results, the incidence of large mutations could be reduced using a rad52 mutant strain in maintenance of centromeric DNA repeat arrays. This genetic method may use more general application in the maintenance of tandem repeats in construction of HAC.