NIPPON SUISAN GAKKAISHI
Online ISSN : 1349-998X
Print ISSN : 0021-5392
ISSN-L : 0021-5392
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Volume 77, Issue 3
Displaying 1-45 of 45 articles from this issue
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Prize Winners of the Japanese Society of Fisheries Science Awards 2010
The Japanese Society of Fisheries Science Award 2010
Scientific Achievement Award in Fisheries Science 2010
Originals
  • Catch of soft-shelled male snow crab Chionoecetes opilio by Danish seiners in the waters off Kyoto Prefecture and their survival ratio after release at sea
    ATSUSHI YAMASAKI, TOSHIAKI MIYAJIMA, KUNIHIRO FUJIWARA
    Article type: Originals
    2011 Volume 77 Issue 3 Pages 372-380
    Published: 2011
    Released on J-STAGE: October 06, 2011
    DOIhttps://doi.org/10.2331/suisan.77.372
    JOURNAL FREE ACCESS
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      This paper describes the estimation of catch in number of soft-shelled males Chionoecetes opilio caught by commercial Danish seiners and their survival ratio just after release at sea during the snow crab fishing season (Nov.-Mar.). Soft-shelled males are sexually non-functional with low commercial value. Soft-shelled males caught by Danish seine were put in experimental traps, and soaked in the fishing ground for about six hours, then retrieved to the research vessel for observation of their survival/mortality. Mean total catch in number of soft-shelled males was estimated at 168,400 individuals in the waters off Kyoto Prefecture based on the fishermen's log-books received in 2006-2008. The estimated number of soft-shelled males is approximately 1.7 times higher than that of hard-shelled males. The survival ratio of soft-shelled males released was estimated at 14.8-95.9% for small size (90-109 mm CW), 5.0-89.8% for medium size (110-129 mm CW), and 0-62.5% for large size (≥130 mm CW). If landings of soft-shelled males were prohibited, the mean survival rate during the soft-shelled male fishing season (Jan.-Mar.) would be as high as 83.6%. This suggests that the protection of soft-shelled males leads to an increased abundance of hard-shelled males resulting in higher economic benefit.
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  • A new method for decreasing the rate of nuclei expelled from post-operative pearl oysters Pinctada fucata in tanks at constant temperature
    TAKASHI ATSUMI, TAKASHI ISHIKAWA, NARIAKI INOUE, RYO ISHIBASHI, HIDEO ...
    Article type: Originals
    2011 Volume 77 Issue 3 Pages 381-386
    Published: 2011
    Released on J-STAGE: October 06, 2011
    DOIhttps://doi.org/10.2331/suisan.77.381
    JOURNAL FREE ACCESS
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      We examined the relationship between the rate of nuclei expelled and variation in water temperature. Pearl oysters had been implanted with a mantle graft and a nucleus. Then oysters were kept for 14 days either in tanks with seawater at constant temperature, or in tanks in which the water temperature was periodically varied. The rate of nuclei expelled from oysters exposed to varying water temperature was significantly higher than that from oysters kept at constant temperature. In a second experiment, implanted oysters were kept for 14 days, either in a closed recirculating tank at constant temperature or suspended from a raft in Ago Bay. The rate of nuclei expelled from oysters kept in the sea was significantly higher than that from those maintained in the recirculating tank. These results suggest that keeping post-operative pearl oysters in a tank at constant water temperature reduces the rate of nuclei expelled.
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  • Early life ecology of nigorobuna Carassius auratus grandoculis in reed zone of Lake Biwa and physiological adaptation to the environment
    KOH-ICHI FUJIWARA, TAKAHIRO USUKI, MORIHITO NEMOTO, SHUICHI KITADA
    Article type: Originals
    2011 Volume 77 Issue 3 Pages 387-401
    Published: 2011
    Released on J-STAGE: October 06, 2011
    DOIhttps://doi.org/10.2331/suisan.77.387
    JOURNAL FREE ACCESS
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      The early life ecology of nigorobuna Carassius auratus grandoculis was investigated in order to determine the requirements for developing breeding grounds and effective release sites for its stock enhancement in Lake Biwa. Larval nigorobuna within the well-developed reed zone swarmed actively near the shoreline immediately after release and began to leave the reed zone when they grew to the juvenile stage of approximately 16 mm in standard length. Zooplankton used as food for the larvae were abundant near the shoreline in the reed zone, but there was remarkably little dissolved oxygen. It was confirmed that the larvae have a high hypoxia tolerance and due to their low body specific gravity could easily rise to the water surface where oxygen readily dissolved. The results indicate adaptation of the larvae to the hypoxic environmental condition. It was thought that hypoxic water areas function as feeding sites and as refuges for the larvae.
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  • Softening of fish meat and changes of muscle protein by freeze-thaw enzyme infusion
    TAKAHIRO NAGAI, TAKAHIRO FUKUMA, SAYAKA NAKATSU, KENYA SHIBATA, KOJI S ...
    Article type: Originals
    2011 Volume 77 Issue 3 Pages 402-408
    Published: 2011
    Released on J-STAGE: October 06, 2011
    DOIhttps://doi.org/10.2331/suisan.77.402
    JOURNAL FREE ACCESS
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      We examined softening of cod and squid meat with freeze-thaw enzyme. Commercial protease for food processing was impregnated into the cod and squid meat under reduced pressure after freeze-thaw. Samples were removed from the enzyme solution and reacted at 10°C for 20 hours. The samples were heated at 95°C for 10 min before measuring the hardness. The hardness of cod and squid meat reached 5×104 N/m2 or less and their original shape did not change. The cod and squid meat, into which enzyme was infused, became substantially soft depending upon heating from 40°C to 60°C. SDS-PAGE revealed that their muscle proteins were decomposed by heating. The amount of free amino acid of the softening cod meat increased compared with that before processing. In particular, remarkable increase was observed in proteinogenic amino acid. This technique could be useful for softening fish and squid meat for elder persons and those under nursing care.
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  • Distribution of coliforms and Escherichia coli at fishing ports
    JUN YOKOYAMA, HISAE KASAI, ATSUMI FURUYA, MAMORU YOSHIMIZU
    Article type: Originals
    2011 Volume 77 Issue 3 Pages 409-415
    Published: 2011
    Released on J-STAGE: October 06, 2011
    DOIhttps://doi.org/10.2331/suisan.77.409
    JOURNAL FREE ACCESS
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      To control the hygienic conditions of fishery products from catching to landing and processing, both qualitative and quantitative bacterial observations at fishing ports must be considered. Thirty-six fishing ports in Hokkaido, northern Japan, were selected and the distributions of coliform bacteria were studied at these sites. Coliforms were observed from all fishing ports, and Escherichia coli were observed from 30 fishing ports. Especially, in relation to the number of coliform bacteria and E. coli, fishing ports which are located near a river show higher levels than any other fishing ports.
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