• Title/Summary/Keyword: shark

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Bycatch of sharks in Korean tuna longline fishery (한국다랑어연승어업에 있어서 상어류의 부수어획)

  • Moon, Dae-Yeon;Hwang, Seon-Jae;An, Doo-Hae;Kim, Soon-Song
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.43 no.4
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    • pp.329-338
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    • 2007
  • Data collected by on-board observers and from experimental surveys during 2004-2006 were analyzed to figure out the status of shark bycatch in Korean tuna longline fishery. Results obtained from 10 surveys indicated that 14, 13 and 1 species of shark were incidentally caught in Korean tuna longline fishery operated in the Pacific, Indian and Atlantic (Mediterranean) Ocean, respectively, and that shark bycatch accounted for about 29-31% of the total catch. Sharks brought aboard were processed in 3 ways; out of 1,127 sharks observed, 575 sharks (51.0%) were discarded after finning, 299 sharks (26.5%) were stored frozen after finning for future use and 253 sharks (22.4%) were released into the sea immediately after caught. The fin to body weight ratio of sharks was estimated to be about 4.7% which is similar to the guideline of 5% established by the international fisheries organizations. The underestimate of shark bycatch in Korean tuna longline fishery was significant because it was general practice that fishermen on-board did not count the discarded shark as a catch.

Effect of the Gonadotropin-Releasing Hormone (GnRH) on Induction of Maturation in White-Spotted Bambooshark Chiloscyllium plagiosum (성 성숙 자극호르몬방출호르몬(GnRH) 투여를 이용한 백점얼룩상어 (Chiloscyllium plagiosum)의 성 성숙 유도에 관한 연구)

  • Ki-hyuk Kim;Ji-min Jeon;Hye-na Moon;Jin Namgung;In-kyu Yeo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.56 no.3
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    • pp.309-314
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    • 2023
  • Shark populations are constantly decreasing owing to environmental destruction and overfishing; thus, sharks are now at risk of extinction, with 30.5% of species classified as endangered on the International Union for Conservation of Nature's Red List. Sharks are apex predators and keystone species in balancing the marine food chain; their extinction would create an imbalance in the entire marine ecosystem. Assisted reproductive technology is a last resort for protecting animals facing extinction. Here, as a proactive effort toward building a hormone-induced artificial insemination protocol for endangered wild sharks, we identified the possibility of germ cell maturation by administration of GnRH, a commercially produced synthetic salmon gonadotropin-releasing hormone, and calculated its optimum dosage and injection timing. The experiment was conducted on one shark species, Chiloscyllium plagiosum. Injections were administered in 24 h intervals to C. plagiosum females, and 0.2 mL/kg+0.2 mL/kg were the optimal doses. These doses effectively induced maturation and, and ovulation, and oocyte release. Our results confirm that GnRH is a suitable tool for shark hormone-induced artificial insemination and indicate that this method may facilitate the conservation of endangered shark species.

Cloning of various bioreactive genes from cartilage tissues of Scyliorhinus torazame (두툽상어 연골 조직에서 생리 활성 유전자들의 cDNA 클로닝)

  • 김지태;김명순;장은령;김영진;김규원
    • Journal of Life Science
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    • v.10 no.5
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    • pp.533-541
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    • 2000
  • Compared to mammal including human, many bioreactive genes that regulate various biological events has not been cloned and characterized yet in fishes, especially shark, Scyliorhinus torazame. In orther to isolate genes that regulate physiological processes in cartilaginors fishes, we performed reverse transcription-polymerase chain reaction (RT-PCR) using the RNA of cartilage tissues of Scyliofhinus torazame. The cloned partial genes were 86%, 80%, 73%, 84%, 75%, 79% identical to $\alpha$- actin, 90-kDa heat-shock protein, methyle-neterahydrofolate dehydrogenase-methenyltertrahydrofolate cyclohudrolase-formyltetrahydrofolate synthetase, ubiquitin, glutamine synthetase and connective tissue growth factor genes of human, respectively. They also have similar nucleotide sequence homologues with those of another species. These partial bioreactive genes elucidated in this study may support to studies of phylogenetic analysis based on evolutionary relationships between shark and other species.

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Distribution of the White Shark, Carcharodon carcharias and Other Sharks around the Korean Waters (한국 연근해 백상아리와 상어류의 분포)

  • Choi, Youn
    • Korean Journal of Ichthyology
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    • v.21 no.sup1
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    • pp.44-51
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    • 2009
  • Greate white sharks, Carcharodon carcharias, are found in almost all the temperate and tropical coastal waters around the world. There have been 19 appearances reported in Korean coastal waters since June 1996 and seven shark attacks have been reported. There are about 400 species of sharks in the world, and 41 species of them have been found in Korean coastal waters. Thirteen of them belong to the Carcharhinidae family, and five of them belong to the Squalidae family. Of these sharks, 15 species of them live off of the East coast, 18 species live off of the West coast, and the other 40 species are distributed around Jeju Island and the South coast. Eleven species of them, including the great white shark, live off of all the coastal waters of Korea.

Preparation of Shark Byproduct Extract and Gellan Gum based Antibacterial Film Containing Green Tea Extract

  • Bak, Jing-Gi;Kim, Jin;Ohk, Seung-Ho
    • Biomedical Science Letters
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    • v.28 no.1
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    • pp.50-57
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    • 2022
  • In this study, we tried to examine the possibility of developing a dental product such as tooth decay prevention and oral hygiene by manufacturing a natural polymer film for oral use. Natural polymer films were prepared from shark byproduct extract (SBE) and gellan gum (GG). As an antibacterial substance, the antibacterial activity of green tea extract against tooth decay-causing bacteria was measured. An film was prepared by adding green tea extract to the composition of SBE and GG. The mechanical, solubility, moisture content and antibacterial function of the prepared film were investigated in detail. Also, the incorporation of GTE into the SBE/GG film improved the physical performance of the film. Increasing the content of GTE improved the antioxidant and antibacterial properties of the film. Formulation of antimicrobial SBE/GG film containing green tea extract was established and these results evidently showed potential for cavity prevention products application.

Comparative Studies on the Enzymatic Properties of Trypsins from Cat-shark and Mackerel -1. Purifications and Reaction Conditions of the Trypsins- (복상어와 고등어의 Trypsin에 관한 비교 효소학적 연구 -1. Trypsin의 정제와 반응조건-)

  • PYEUN Jae-Hyeung;CHO Deuk-Moon;HEU Min-Soo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.24 no.5
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    • pp.273-288
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    • 1991
  • To elucidate the physiological and biochemical differences between chondrichthyes and osteichthyes, the properties of the specific digestive enzymes in cat-shark, Cephaloscyllium umbratile, and mackerel, Scomber japonicus, were studied. Homogenous trypsin proved through the disc-electrophoresis, SDS-PAG electrophoresis and gel filtration was obtained from the pancreas of cat-shark by $50-70\%$ saturated ammonium sulphate fractionation, DEAE-Sephadex A-50 column chromatography, benzamidine-Sepharose 6B affinity chromatography and Sephadex G-75-120 gel filtration. Two types of trypsins were also obtained from the pyloric caeca of mackerel by $30-70\%$ saturated ammonium sulphate fractionation and the slightly modified procedure from the method adopted in the purification of cat-shark trypsin. The two trypsins, designated trypsin A and B, were proved their homogeneity by disc- and SDS-PAG electrophoresis and gel filtration. The molecular weights of the trypsins were estimated to be 31,700 for cat-shark trypsin, 30,000 for mackerel trypsin A and 29,000 for mackerel trypsin B by SDS-PAG electrophoresis, but those were estimated to be 21,500 for cat-shark trypsin, 23,700 for mackerel trypsin A and 21,500 for mackerel trypsin B by gel filtration. The trypsins exhibited their optimum conditions at pH 9.0 and on temperature ranged from $45^{\circ}C\;to\;50^{\circ}C$ for cat-shark, and at pH 8.0 and a temperature of $50^{\circ}C$ for mackerel trypsin A and B, respectively. The cat-shark trypsin was stable at pH 10.0 and the temperature below $10^{\circ}C$, whereas the mackerel trypsin A and B, were stable in the range over pH 7.0 to pH 9.0 below $10^{\circ}C$ and at pH 8.0 below $35^{\circ}C$, respectively. The mackerel trypsins were severely inhibited by some heavy metal ions such as $Ag^{2+},\;Cu^{2+}\;and\;Hg^{2+}$ compared to cat-shark trypsin. All of the enzymes were also inhibited by antipain, leupeptin, TLCK(tosyllysine chloromethyl ketone) and SBTI(soybean trypsin inhibitor) remarkably. The inhibitory effects of PMSF(phenylmethane sulphonylfluoride), DFP(diisopropyl fluorophosphate) and benzamidine were indicated that these enzymes belong to serine-proteases.

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Physicochemical Comparison of Two Different Shark Meats Used for Preparation of Dombaeki (돔배기용 상어육의 이화학적 성분 비교)

  • Kim, Eun-Ok;Yu, Myeong-Hwa;Lee, Ki-Teak;Kim, Seon-Bong;Choi, Sang-Won
    • Food Science and Preservation
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    • v.15 no.5
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    • pp.711-718
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    • 2008
  • Dombaeki, a traditional salted shark meat, has been widely used as a customary religious food in the Daegu-Gyeongbuk area of Korea. Two different sharks, Sphyrna zygaena (SZ) and Isurus oxyrinchus (IO) are traditionally used to prepare Dombaeki. Chemical components, lipid classes, fatty acid levels, and sterol compositions of meats prepared from the two sharks were investigated. There were no significant differences in chemical composition between the two dried shark meats. Major amino acids in shark meat were leucine, lysine, arginine, proline, isoleucine, valine, phenylalanine, glutamic acid, and asparagine, which together accounted for about 40% of total amino acids. Levels of amino acids in IO meat were higher than in SZ meat. Major fatty acids in the two shark meats were palmitic ($C_{16:0}$), stearic ($C_{18:0}$), oleic ($C_{18:1}$), arachidonic ($C_{20:4}$), and docosahexanoic (DHA, $C_{22:6}$) acids, which accounted for about 80% of total fatty acids. Notably, IO meat showed higher amounts of DHA (31.8%) and eicosapentanoic acid (EPA, 1.8%) than did SZ meat. The two shark meats showed similar dry weight levels of total lipids, with triacylglycerols, free fatty acids, sterols, and phospholipidscomprising on average 5.0, 2.0, 13.0 and 63.0% of total lipids, respectively. The dominant classes of phospholipids were mainly phosphatidylcholine (PC) and phosphatidylethanolamine (PE). PC content in the two shark meats was higher than that of PE, although the differencewas not great. The major fatty acids in phospholipids were myristic, palmitoleic, stearic, and docosanoic acids. Total volatile basic nitrogen content and the pH of SZ meat were lower than those of IO meat, whereas the Hunter's 'a' and 'b' values of SZ meat were higher than those of IO meat. These results suggest that shark meat may be useful as a functional food to prevent several degenerative diseases.

Anti-arthritic Effect of a New Diet-Supplement Containing Red Ginseng Extract and Glucosamine Complex (홍삼추출물과 글루코사민 복합제제의 관절염에 미치는 영향)

  • Jeong, Choon-Sik;Hyun, Jin-Ee;Kang, Min-Hee;Sim, Joon-Soo;Son, Mi-Jin;Jung, Sang-Hoon;Kim, Jong-Hoon;Lee, Kwang-Seong;Kim, Yeong-Shik
    • Korean Journal of Pharmacognosy
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    • v.34 no.4 s.135
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    • pp.327-334
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    • 2003
  • We evaluated the anti-arthritic effect of a new diet-supplement product containing red ginseng, glucosamine, shark cartilage, ascorbic acid and manganese chloride for the relieving arthritic symptoms. Anti-inflammatory activities of the aqueous extract of red ginseng (250 and 500 mg/kg), glucosamine (240 mg/kg) and shark cartilage (240 mg/kg) were tested individually on vascular permeability and carrageenan-induced paw edema. Glucosamine and shark cartilage showed the inhibition of vascular permeability by 29.6 and 32.9%, respectively. Red ginseng (500 mg/kg) and shark cartilage showed the inhibition of carrageenan-induced paw edema at 0.5, 1, 2 and 3 hr. The supplement (red ginseng mixture: RGM) composed of red ginseng (43.5%), glucosamine (25.0%), shark cartilage (25.0%), ascorbic acid (5.0%) and manganese chloride (1.5%) was prepared and its inhibitory activities including vascular permeability and carrageenan-induced paw edema were comparable to anti-inflammatory drugs such as diclofenac and ibuprofen. It was also tested on adjuvant-induced arthritis in rats as one of chronic arthritic tests and Randall-Selitto assay as an analgesic test. RGM showed the inhibition against the swelling of rat paws induced by Mycobacterium tuberculosis at a dose of 1,500 mg/kg. Determination of cytokines of the sera sampled from arthritis-induced animals indicated that RGM increased the levels of $interferon-{\gamma}$ and interleukin-6, representing the immunostimulatory effect by red ginseng. RGM treatment moderately reduced the production of NO in RAW 264.7 cells in a dose-dependent manner. Taken together, these results support that RGM can be applicable for the improvement of arthritic as a new diet-supplement.

3D Elastic Contact Analysis of Sharkskin Surface Pattern (상어 표피 형상의 3차원 탄성접촉해석)

  • Kim, Tae Wan
    • Tribology and Lubricants
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    • v.28 no.6
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    • pp.297-302
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    • 2012
  • We conducted 3D elastic contact analysis of a sharkskin surface pattern for the characteristic assessment of biomimetic shark skin structure pattern for engineering applications. Rough sharkskin surfaces of similar size with real shark skin scales are generated numerically. Under the assumption of the contact of a plate on the generated sharkskin surface, contact performances such as contact pressure, real contact area, and surface separation are evaluated.

Physical Property and Extraction of Squalene and Alkoxyglycerol from Shark Liver Oil (상어간유에서 스쿠알렌과 알콕시글리세롤의 물성 및 추출)

  • Lee, Su Il;Heo, Hyo Jung;Row, Kyung Ho
    • Korean Chemical Engineering Research
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    • v.49 no.5
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    • pp.617-622
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    • 2011
  • A simple method has been successfully applied to extract squalene and its byproducts alkoxyglycerol from deep-sea shark liver oil. GC-MS was used to determine the extraction amount of the squalene and alkoxyglycerol, and the content of them in rough product and refined product were compared. The physical property of squalene was identified by measuring the pH value, peroxide value and iodine value. Under optimum extraction conditions, the amount of squalene and alkoxyglycerol increased 35.0% and 21.9%, respectively, while the amount of fatty acid decreased from 61% to 4%, especially, the amount of palmitic acid and oleic acid remarkably decreased. Large amount of peroxide and acid were removed from shark liver oil after refining process. Because squalene contains lots of double bond, so the value of iodine is much higher than squalane.