NIPPON SUISAN GAKKAISHI
Online ISSN : 1349-998X
Print ISSN : 0021-5392
ISSN-L : 0021-5392
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Volume 75, Issue 2
Displaying 1-31 of 31 articles from this issue
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  • Effect of water flow on 3-dimensional underwater shape of pelagic longline with midwater float
    MICHIRU SHIGA, DAISUKE SHIODE, YOSHINORI MIYAMOTO, KEIICHI UCHIDA, FUX ...
    2009 Volume 75 Issue 2 Pages 179-190
    Published: 2009
    Released on J-STAGE: April 16, 2009
    DOIhttps://doi.org/10.2331/suisan.75.179
    JOURNAL FREE ACCESS
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      A midwater float system for pelagic longlines was developed to reduce sea turtle incidental catch and to improve tuna catch efficiency. This paper presents changes in the three-dimensional shape of the pelagic longline with midwater float by water flow. The 3-dimensional underwater shape of the pelagic longline with a mainline of 180 m length in one basket was measured, using an ultrasonic positioning system and GPS buoy, and simultaneously the water currents at 11 depth levels (from 10 m to 60 m at 5-m intervals) were measured by an acoustic Doppler current profiler. The whole longline gear drifted in the direction of the current at the same depth where the mainline was located, because the mainline was most influenced by the drag of the water flow. Similarly, the hook of the branch line was shoaled in the current direction. Due to the current component parallel to the mainline, the mainline was skewed downstream, and the slack of the downstream part in the mainline became large while the upstream part of the mainline was shoaled. Especially, when a large difference was found in the current direction and velocity between the vertical depths, complicated 3-dimensional deformation occurred on the mainline.
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  • Effectiveness of Paddy Fields as an Initial Growth Environment for Larval and Juvenile Nigorobuna Carassius auratus grandoculis
    SHIGEFUMI KANAO, TAISUKE OHTSUKA, MASAYOSHI MAEHATA, NORIYASU SUZUKI, ...
    2009 Volume 75 Issue 2 Pages 191-197
    Published: 2009
    Released on J-STAGE: April 16, 2009
    DOIhttps://doi.org/10.2331/suisan.75.191
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      Carassius auratus grandoculis larvae and juveniles were released in paddy fields near Lake Biwa. Later, they were periodically collected and subject to growth analysis of total length (TL) and body weight (BW). As a result, daily growth rates in both TL and BW reared in paddy fields were high in comparison to those of fish reared in fishery ponds and raised naturally in reed zones of Lake Biwa. The survival rate of C. a. grandoculis in paddy fields increased with lower population density. Meanwhile, daily growth increments shifted from an increase to a decrease at 11-24 days of age in TL, and at 15-44 days of age in BW. Therefore, paddy fields are considered to be highly effective as an initial growth (until about 40 days of age) environment for C. a. grandoculis.
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  • Survival, growth, density and standing stock of underyearling white-spotted charr Salvelinus leucomaenis from eyed eggs stocked in a Japanese mountain stream
    TOMOYUKI NAKAMURA, TAKAHIDE DOI
    2009 Volume 75 Issue 2 Pages 198-203
    Published: 2009
    Released on J-STAGE: April 16, 2009
    DOIhttps://doi.org/10.2331/suisan.75.198
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      We stocked eyed eggs of the white-spotted charr Salvelinus leucomaenis in fish-uninhabited reaches of the Kirizushisawa Stream of Kinu River, Tone River System, central Japan in January 2005 and 2006 using the Vibert box technique and surveyed the incubation rate, survival rate, growth, density and standing stock of the underyearling charr from the eyed eggs between August and November. In each year, the incubation rates were 93.2 and 99.0% and survival rates from eyed egg to November were 5.6 and 3.6%. The average standard length and body weight were 57.4 mm, 3.8 g and 60.3 mm, 3.8 g, and density and standing stock per 1 m2 water surface were 0.67 fish, 2.6 g and 0.48 fish, 1.8 g in November for each year, respectively. The number of eggs/fish decreased exponentially from January to November in both years.
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  • Age and hatching date of Japanese common squid, Todarodes pacificus, in waters around Hokkaido
    KENJI SAKAGUCHI, TORU SATO, MASAKI MITSUHASHI, HIDEAKI KIDOKORO
    2009 Volume 75 Issue 2 Pages 204-212
    Published: 2009
    Released on J-STAGE: April 16, 2009
    DOIhttps://doi.org/10.2331/suisan.75.204
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      Statolith increment analysis was applied to 1,421 specimens of the Japanese common squid, Todarodes pacificus, to estimate the age and hatching date. Samples were collected during May-November in 2001 and 2002 in the waters around Hokkaido. Two hatching groups were observed in waters around Hokkaido: November- to December-hatched T. pacificus and February- to May-hatched T. pacificus. During May-September, November- and December-hatched squid predominated in the Sea of Japan off Hokkaido and in waters off southern Hokkaido. Squid that hatched in February-May were predominant in waters off southern Hokkaido and the Pacific coast off eastern Hokkaido during August-October, and during October-November in the Okhotsk coast off Hokkaido and the Sea of Japan off Hokkaido. It was found that between August and September, both hatching groups occurred in waters off southern Hokkaido.
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  • Simple method to identify two species of hairtails, Trichiurus japonicus and T. sp.2, in Shikoku Island
    SHIN ICHI YANAGAWA, SEI ICHI WATANABE
    2009 Volume 75 Issue 2 Pages 213-218
    Published: 2009
    Released on J-STAGE: April 16, 2009
    DOIhttps://doi.org/10.2331/suisan.75.213
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      A morphological method was developed to distinguish the two species of hairtails Trichiurus spp. (Trichiuridae) distributed in Shikoku Island. A total of 2,179 specimens of Trichiurus japonicus and T. sp.2. were collected from coastal waters off Ehime prefecture and Kochi prefecture from January 2004 to February 2006. The relationship between preanal length (PL) and total length (TL) was expressed as the linear discriminant function z=0.133 PL+59.6 TL/PL-207. The rate of misidentification of fish was 2.0% compared to the identification based on the previous criterion proposed by Nakabo (yellow dorsal fin and light-colored bottom of oral cavity for fresh specimens). Condition factor of T. sp.2 was higher than that of T. japonicus, and the range of condition factors was 13.81-22.66 and 9.88-18.02, respectively. Furthermore, comparing the condition factors, the misidentification rate was only 0.4%. This identification method may be applicable for past studies which measured only fish body without precise species identification.
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  • Improvement of species- and size-separation in SURF-BRD with high encounter probability of marine organisms
    YORITAKE KAJIKAWA, TADASHI TOKAI, FUXIANG HU
    2009 Volume 75 Issue 2 Pages 219-229
    Published: 2009
    Released on J-STAGE: April 16, 2009
    DOIhttps://doi.org/10.2331/suisan.75.219
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      SURF-BRDs which is composed of a pair of rectangular net panels (front panel (FP) with square mesh of 80 mm mesh size, rear panel (RP) with diamond mesh of 27.5 mm mesh size) and two fish vents, was developed for small-scale shrimp beam trawling to separate species and size of fish by the probability of marine organisms encountering the two panels and the mesh selectivity. In this study, the BRD-mounting arrangement and net plan were both improved to maintain the heights of BRD and net mouth for the purpose of more effective separation. As a result of a fishing experiment with the improved BRD trawl, the height of the improved BRD was about 1.7 m, which is much higher than the 0.4 m height of the prototype SURF-BRD. Therefore, the probability of encountering Lizardfish Saurida spp. and Cinnamon flounder Pseudorhombus cinnamoneus became higher, achieving more effective size separation of these species by mesh selectivity of the FR. While small crabs were eliminated through the vent after passing through the FP, most small shrimps, which were the main target species, were caught in the codend.
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  • Effects of culture density on the growth and fecal production of the oyster Crassostrea gigas
    TAMIJI YAMAMOTO, HAJIME MAEDA, OSAMU MATSUDA, TOSHIYA HASHIMOTO
    2009 Volume 75 Issue 2 Pages 230-236
    Published: 2009
    Released on J-STAGE: April 16, 2009
    DOIhttps://doi.org/10.2331/suisan.75.230
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      The effects of culture density on the growth and fecal production of the oyster Crassostrea gigas in Hiroshima Bay were estimated using a numerical model expressing physiological processes of the oyster by changing the rate of water exchange into and out of the cultivation raft. While the individual-based growth of oyster was higher with decreasing culture density, total production was highest with 850 wires per raft. The individual-based fecal production increased with decreasing culture density, but the total amount of fecal production was highest with 950 wires per raft. From these results, it was concluded that 850 wires per raft was the appropriate cultivation density under the environmental conditions of Hiroshima Bay with no consideration of sediment deterioration.
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  • Storage of sea urchin gonad in oxygenated sea water
    YASUNORI KINOSHITA, TAKEYA YOSHIOKA, SYUN-ICHI MIYAZAKI, SANAE KATO, K ...
    2009 Volume 75 Issue 2 Pages 237-243
    Published: 2009
    Released on J-STAGE: April 16, 2009
    DOIhttps://doi.org/10.2331/suisan.75.237
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      Changes in the contents of ATP related compounds in the gonad of sea urchin Strongylocentrotus nudus stored in artificial seawater were investigated. A gradual decrease of ATP content was followed by an accumulation of HxR and Hx during storage, while total nucleotide content decreased from 2.6 to 1.2 μmol/g in 8 days indicating a leaking of the compounds from the gonad. The ATP content relative to the sum of ATP related compounds was used to show the ATP content of the gonad. Turbidity of seawater used for storage, a commercial sensory freshness index of gonad of sea urchin, also increased during storage. The increase in turbidity seemed to correspond to the decrease in relative ATP content. The effect of oxygen volume filled in the storage bag on the change in the relative ATP content of gonad and on the turbidity increase of seawater was studied. Decrease in the relative ATP content and turbidity development were both suppressed by an increase in filled oxygen volume. Almost no increase in the marine bacteria population was observed during the storage under any conditions. It was concluded that storage of sea urchin gonad in oxygenated sea water was an effective method for main taining freshness.
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  • Histochemical properties of eosin-Y positive components proposed as an index for judging the quality of katsuobushi
    TATSUHITO YOSHIOKA, NOZOMU OGINOME, SHINICHI SASAKI, MASAKAZU YOSHIDA, ...
    2009 Volume 75 Issue 2 Pages 244-249
    Published: 2009
    Released on J-STAGE: April 16, 2009
    DOIhttps://doi.org/10.2331/suisan.75.244
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      Histochemical properties of eosin-Y positive component (EPC), which was proposed as an index for judging the quality of katsuobushi, were examined in terms of immunohistochemistry using anti-actin, -myosin, -lactate dehydrogenase (LDH), and -myoglobin polyclonal antibodies or antiserum. EPC was reacted with four antibodies and the reactants were detected dominantly in the intracellular compartmentation of muscle cell in the katsuobushi manufactured from raw materials caught by pole and line (KPL) and in the intercellular space of muscle cell in the katsuobushi manufactured from raw materials caught by purse seine (KPS).
       Immunohistochemical analysis with anti-laminin polyclonal antibody revealed the existence of a significant number of cells with unclear endomysium, suggesting cell disruption, in KPS in comparison with KPL.
       These results suggested that EPC was mainly composed of myofibrillar and sarcoplasmic proteins such as actin, myosin, LDH and myogloblin, and that the reduction of the intracellular EPC in KPS was caused by the spillage of EPC from the intracellular compartmentation of muscle cell to the intercellular space resulting from endomysium disruption being due to unknown factors in the manufacturing process of KPS.
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  • Heated gel forming ability of walleye pollack frozen surimis of various grades, as measured by physical properties of heated gel and its dependence on protein concentration
    SEIICHI KITAKAMI, YURIKO MURAKAMI, KOSAKU YASUNAGA, YOICHI ABE, NOBORU ...
    2009 Volume 75 Issue 2 Pages 250-257
    Published: 2009
    Released on J-STAGE: April 16, 2009
    DOIhttps://doi.org/10.2331/suisan.75.250
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      From ten lots of walleye pollack frozen surimis of various grades, the heated gels of different protein concentrations were prepared by adding 0-150% water. Breaking strength (BS), breaking strain (bs), and gel stiffness (Gs=BS/bs) were measured, and the effect of the protein concentration of the heated gel on their physical values was analyzed. The results were as follows: (1) Of all the surimis tested, the BS and Gs of the heated gel increased exponentially with the increase in the protein concentration of the heated gel. (2) The maximum values of BS and Gs of the heated gels formed without addition of water were higher in the order of SA>FA>A>KA>2nd grades of frozen surimi. (3) When BS was plotted against Gs, there was a close, positive correlation among those of the heated gels from the ten lots of frozen surimis of various grades. These results indicated that the heated gel forming ability, as measured by BS and Gs levels of the heated gel and its dependence on the protein concentration, is a useful parameter for judging the quality of walleye pollack frozen surimi.
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