NIPPON SUISAN GAKKAISHI
Online ISSN : 1349-998X
Print ISSN : 0021-5392
ISSN-L : 0021-5392
Volume 77, Issue 5
Displaying 1-40 of 40 articles from this issue
Technical Achievement Award in Fisheries Science 2010
Originals
  • AKI MIYAGI, KAZUO AMAKASU, KOKI ABE, TOMOHITO IMAIZUMI, YOSHINORI MIYA ...
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 791-798
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      The purpose of this study was to clarify the change of the source level (SL) of a pinger implanted in a fish and its influence on the receiving distance of an ultrasonic biotelemetry system. A nondirectional transmitter was implanted in three southern bluefin tuna instead of a pinger and the SL of the implanted transmitter was measured from various directions for each tuna. As a result, it was confirmed that the SL changed according to the direction. The maximum decrease of the SL was about 34 dB and the decrease in the receiving distance was estimated to be about 460 m. Our results suggest that the SL and the receiving distance are decreased by implanting a pinger in a fish.
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  • SHINGO WATARI, MAKOTO ISHITANI, SHIGEYUKI ODA
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 799-808
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      A stock assessment of Japanese mantis shrimp Oratosquilla oratoria was conducted using research data sampled by small trawl vessel in the Buzen Sea, Seto Inland Sea, Japan, from 2007 to 2009. The fishing mortality coefficient estimated for every half-year from the 2007 year class suggested that the reduction of population by discard began soon after recruitment. The survival rate after one year of recruitment was estimated as 13.4%. The reduction of individuals before growing to the minimum landing size was large. The yield per recruit and spawning per recruit analyses show that to increase both catch and egg production, reduction of fishing effort until two years after settlement is effective. It is particularly important to reduce the fishing effort during the next summer after settling which includes high discard mortality.
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  • HIROSHI YAMAGUCHI, SHUICHI NISHIUCHI, SHIRO TAKAYANAGI, KAZUSHI MIYASH ...
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 809-821
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      We aimed to estimate the size selectivity of the shrimp pot for the northern shrimp Pandalus eous by the SELECT analysis method. Comparative fishing experiments were conducted by using shrimp pots of different mesh sizes (bar length: 13.99, 15.30, 16.84, and 19.13 mm) with control pots of 5.33 mm. We obtained size selective curves for non-ovigerous and ovigerous shrimps. The carapace lengths of 50% of the non-ovigerous shrimps caught (L50) with mesh sizes of 13.99, 15.30, 16.84, and 19.13 mm were 20.10, 22.75, 26.25, and 28.64 mm, respectively. The carapace lengths of ovigerous shrimps caught with a mesh size of 19.13 mm were significantly different from those of shrimps caught with a non-selective mesh size of 5.33 mm. Therefore, mesh size of less than 19.13 mm was nonselective for ovigerous shrimps. The L50 of ovigerous shrimps caught with a mesh size of 19.13 mm was 25.74 mm. The percentage changes in the total catch and income were calculated when mesh sizes of more than 15.30 mm were used: they decreased by 11.8% and 9.5%, respectively, when the mesh size was modified to 16.84 mm, while they decreased by 31.2% and 27.8%, respectively, when the mesh size was modified to 19.13 mm.
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  • KOH-ICHI FUJIWARA, TAKAHIRO USUKI, MORIHITO NEMOTO, MASAYA MATSUO, SYO ...
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 822-833
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      Effective release strategies for nigorobuna Carassius auratus grandoculis in Lake Biwa were investigated by release-recapture experiments of otolith marked nigorobuna with ALC. As a result, nigorobuna arrived at the juvenile stage exceeding approximately 16 mm in standard length and released to the Phragmites australis reed zone showed a rapid increase in survival rate. A remarkable decrease in the survival rate of stocked fish in the lake was observed in cases of 1) release to the reed-free lake shore, 2) reduction of the depth of flooded reed zone according to draw down of water level by artificial manipulation, 3) growth retardation of reed in spring by excessive cutting management of reed in winter, and 4) excessive release of nigorobuna larvae to a limited reed zone. Larvae-release techniques which overcome the problems and reed zone-independent release methods for nigorobuna should be developed in the future.
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  • MASAKI ICHIMURA, TAKASHI YANAGIMOTO, TAKANORI KOBAYASHI, TETSUJI MASAO ...
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 834-844
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      “Sakemasu” collected in the Nemuro Strait was identified as a hybrid between chum salmon Oncorhynchus keta and pink salmon O. gorbuscha using analyses of mtDNA and nuclear DNA. The nucleotide sequences of ATPase6, NADH3 of mtDNA and ITS1, ITS2, and Aromatase B-1 of nuclear DNA of O. keta and O. gorbuscha were compared to construct species specific primers (SSP). The combined results of SSP-PCR analysis of mtDNA and nuclear DNA indicated that six individuals from eleven “Sakemasu” are hybrids between chum and pink salmon. Some morphological features of crossbred “sakemasu” were mixed with parental traits.
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  • AKIHIKO IMAI, TAKASHI IWASAKI, HIROSHI HASHIMOTO, YOSHIRO HIRATA, KATS ...
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 845-852
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      To understand the mechanism of the initial swim bladder inflation of greater amberjack Seriola dumerili larvae, we reared larvae from two days after hatching (DAH) in tanks in which the water surface was sealed with liquid paraffin. This treatment prevented the larvae from access to air through the water surface. Furthermore, we examined the ontogenetic development of larval swim bladders. Percentages of larvae with inflated swim bladders were very low in tanks with the sealed water surface compared with those in the tanks in which the oil film was removed from the water surface. A swim bladder was formed as a protuberance from an upper portion of the intestine. A pneumatic duct which connected the swim bladder to the intestine was observed in larvae of 3 DAH. The pneumatic duct was obstructed and separated from the swim bladder in larvae of 5 DAH. Our experiments revealed that a mouth-opened larva of greater amberjack inflates its swim bladder by gaping air from the water surface and introducing it into the swim bladder through the pneumatic duct from 3 to 4 DAH.
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  • KOH-ICHI FUJIWARA, SHUICHI KITADA
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 853-861
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      Near the shoreline of the well-developed reed zone of Lake Biwa, the dissolved oxygen concentration is remarkably low, but the water temperature is high and microcrustaceans which are preyed on by larval nigorobuna Carassius auratus grandoculis are abundant. Larval nigorobuna aggregate actively around this water area. Factors affecting this aggregation behavior were examined using two kinds of avoidance/preference test apparatus. Our examinations proved that larval nigorobuna do not avoid hypoxic water, but prefer high-temperature water, avoid heavily shaded environments, are strongly attracted to microcrustacean, and prefers the shoreline water containing an abundance of microcrustaceans in the reed zone over the outer-edge water with few microcrustaceans. It is important to take account of the ecological and environmental factors for developing breeding grounds of nigorobuna and selecting effective release sites for its stock enhancement in Lake Biwa.
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  • MASAYUKI YAMAMOTO, TAIZOU NAGANO, HIROYASU MAKINO, YUTAKA UETA, HIROSH ...
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 862-870
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      Natural infections of adult Neoheterobothrium hirame, a haematophagous monogenean parasite, on Japanese flounder Paralichthys olivaceus in the central Seto Inland Sea off Kagawa Prefecture, Japan, were monitored from 1997 to 2010. N. hirame was found for the first time in the survey area in 1998, and the prevalence rapidly increased annually, reaching a peak level of 52.4% in 2000, then remained at the high level until 2005, and subsequenty suffered a sharp and constant decline until 2010. Occurrences of severely anemic fish were rare and condition factors of the affected fish were not related to N. hirame infection. Whereas the prevalence and intensity of the parasite were statistically irrelevant to the sex or age of the host, they were significantly higher in winter and spring than in summer and fall, indicating a seasonal fluctuation. The prevalence and intensity in the survey area were lower than those reported in the western sea of Japan, which might be affected by environmental factors and biological features of Japanese flounder in this area, including drastic seasonal changes of the water temperature, higher than 25℃ in summer and lower than 10℃ in winter, and differences in their habitat in the Seto Inland Sea between 0-year-old naïve fish and one- to two-year-old infected fish.
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  • AKIHITO TERAI, FUSAICHI YAMAMOTO, TOMOTAKA OHASHI, HARUHIKO TOYOHARA
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 871-875
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      With the aim of utilizing the oyster shells which are generally discarded in shell culture, we have developed an efficient precipitator to clarify muddy water from a baked oyster shell.
       We examined the effect of baking temperature (200℃, 300℃, 400℃, 500℃, and 600℃) on the effect of precipitation and found that 400℃ was the most effective baking temperature to produce a precipitator. The efficiency of precipitation was evaluated as the precipitation ability of the baked shell in muddy water containing kaolin. Precipitators made of shell baked at temperatures below 300℃ were more efficient under slow stirring conditions, while those baked at temperatures above 500℃ were more effective under fast stirring conditions. Precipitators made of shell baked at 400℃ were effective under both stirring conditions. The specific surface area and grain size of the shell reduced with the increase in baking temperature. This is possibly because 400℃ is a suitable baking temperature for both generating the small grain size that is effective for flock formation and realizing a large specific surface area necessary for the physical strength of the flock.
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  • TETSUYA NISHIKAWA, ICHIRO IMAI
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 876-880
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      The seasonal changes in cell density and cell size of the harmful diatom Eucampia zodiacus were investigated for seven years (April 2002-March 2009) in Harima-Nada, the eastern part of the Seto Inland Sea, Japan. Vegetative cells of E. zodiacus were detected year-round in water columns, and the restoration of cell size occurred once in autumn every year just after reaching the minimum cell size. Average cell densities of the E. zodiacus population in autumn had a significant negative correlation with the integrated number of days during the period from restoration cell size to peak of the bloom. It was considered that vegetative cells of E. zodiacus observed in autumn play an important role as seed populations in winter and early spring blooms. Therefore, it is proposed that the time of “nori” bleaching occurrence can be predicted by monitoring the cell size restoration and the mean cell density of E. zodiacus in autumn in Harima-Nada.
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  • YOICHRO HAMA, YOSHIMASA TSUNEDA, RYOKO SUGIMOTO, HIROKI NAKAGAWA
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 881-886
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      By the extraction of dried sheets of susabinori, Porphyra yezoensis, with 80% EtOH at 75℃, the solvent soluble pigments and low molecular weight compounds were removed. The decolorized nori samples were dried, and were crushed with a Wonder Blender to obtain fine powders. Constituent monosaccharides of the polysaccharides in the powders were liberated quantitatively by anhydrous mercaptolysis, as described previously. The liberated monosaccharide diethyl dithioacetal derivatives were trimethylsilylated and then analyzed by GLC. The derivatives of galactose, 6-O-methylgalactose, 3,6-anhydrogalactose, xylose, mannose, and glucose were detected in all nori samples tested. Individual polysaccharide contents were calculated from the amounts of corresponding component monosaccharides. Namely, porphyran contents were obtained from the sum of the amounts of galactose, 6-O-methylgalactose, and 3,6-anhydrogalactose, and xylan, mannan, and starch contents were obtained from the amounts of xylose, mannose, and glucose, respectively. Contents of the polysaccharides except for starch increased with growth of nori blade, and the increments in porphyran and xylose were significant. In addition, ratios of 3,6-anhydrogalactose and 6-O-methylgalactose in porphyran increased with prolonged cultivation period. It is apparent that the polysaccharide contents and the properties of porphyran respond to the growth of nori blade.
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  • YURI TAKEUCHI, HIDEHITO TAKAHASHI
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 887-895
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      The change of tissue strength in prawn by heat treatment (boil, retort (121℃, F0=6)) was studied. The physical and chemical properties of prawn after heat treatment were measured by X-ray computerized tomography (CT), scanning electron microscopy (SEM) and environmental scanning electron microscopy (ESEM), and chemical analysis for percentage of gelatin in collagen. According to the results of the strength of muscular tissue, the retorted sample was the softest. By measurement of X-ray CT, the muscle density of the retorted sample was lower than that of the boiled sample. The muscle fibers of raw and boiled samples were wrapped by connective tissue, but the retorted sample was partially-removed was viewed under ESEM. The gelatinization rate of collagen in the retorted sample was higher than that of the boiled one. It is suggested that the softness of prawn tissue by sterilization is caused by gelatinization of collagen.
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  • HITOMI SUZUKI, MASAYA KIMOTO, YUTA YOSHIZOE, TOSHIHIRO TSUNEYOSHI, NOB ...
    Article type: Originals
    2011 Volume 77 Issue 5 Pages 896-901
    Published: 2011
    Released on J-STAGE: October 11, 2011
    JOURNAL FREE ACCESS
      A DNA analysis method has been developed for detecting the mixing of foreign species of eel among about 100 putative all Anguilla japonica eels, with high accuracy and low cost at the level of commercial products. Allele specific PCR (AS-PCR) assay was used to detect the non-A. japonica allele by using primers that match the 3′ end nucleotides of the mitochondrial DNA cytochrome b gene sequence of all known eel species except A. japonica. Foreign species specific PCR products, if obtained, were subjected to restriction fragment length polymorphism (RFLP) assay to quickly identify the species from the difference of digestion fragment patterns by using Rsa I and Hinf I as the restriction enzymes.
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