NIPPON SUISAN GAKKAISHI
Online ISSN : 1349-998X
Print ISSN : 0021-5392
ISSN-L : 0021-5392
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Volume 73, Issue 2
Displaying 1-23 of 23 articles from this issue
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Originals
  • Stocking effectiveness of Japanese Spanish mackerel Scomberomorus niphonius in the eastern Seto Inland Sea
    HIDEKI YAMAZAKI, HIROMASA TAKEMORI, AKIO IWAMOTO, SHIGENOBU OKUMURA, H ...
    2007 Volume 73 Issue 2 Pages 210-219
    Published: 2007
    Released on J-STAGE: April 03, 2007
    DOIhttps://doi.org/10.2331/suisan.73.210
    JOURNAL FREE ACCESS
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      In order to estimate the stocking effectiveness of Spanish mackerel Scomberomorus niphonius 36-40 mm (40 mm group) and 93-150 mm (100 mm group) in total length were marked on the otolith with alizarin complexone and stocked in the eastern part of the Seto Inland Sea in 2002 and 2003. Through a survey at the major landing markets in the area, the contribution rates of stocked fish to the total landings for 0 and 1 year-old fish were estimated to range from 4-42% and the total amount of landings from stocked fish ranged from 8.3 to 21.6 tons. Stock enhancement of Spanish mackerel was shown to substantially contribute to the fisheries production of this species. Recapture rates until 1 year-old fish were estimated at 0.89-15.75% and the economic efficiency ranged from 0.14 to 1.60, showing that stocking the 100 mm group in 2003 was profitable even for 1 year-old fish.
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  • Evaluation of a conventional otter board used in trawl fishery in Ise-wan Bay and proposal of a new design
    SHINTARO YAMASAKI, YOSHIKI MATSUSHITA, TOSHIHIKO KAWASHIMA, MINORU TOM ...
    2007 Volume 73 Issue 2 Pages 220-225
    Published: 2007
    Released on J-STAGE: April 03, 2007
    DOIhttps://doi.org/10.2331/suisan.73.220
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      To improve the otter board used with a semi-pelagic trawl net, we evaluated the conventional otter board used in Ise-wan Bay and compared the lift and drag characteristics with the following experimental otter board. The experimental otter board was designed to enable both semi-pelagic and bottom trawl operations along with a high lift-drag ratio. Results of model experiments indicated that the drag coefficient of the experimental otter board was smaller, and the lift-drag ratio of the experimental otter board was 1.41 times higher than those of the conventional otter board respectively at intended attack angles. In an experimental operation using a semi-pelagic trawl net, the otter board distance was 1.1-1.2 times wider than that of the conventional otter board.
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  • Improvement of larval survival rates by water agitation and medication in the seed production of snow crab Chionoecetes opilio
    TAKAYUKI KOGANE, KATSUYUKI HAMASAKI, SHIGEKI DAN
    2007 Volume 73 Issue 2 Pages 226-232
    Published: 2007
    Released on J-STAGE: April 03, 2007
    DOIhttps://doi.org/10.2331/suisan.73.226
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      Behavioral characteristics of snow crab Chionoecetes opilio larvae such as phototaxis and geotaxis in relation to their depth regulation were examined in the laboratory. Further, effects of agitation and bath treatment with sodium nifurstyrenate (NFS-Na) for larval rearing water on survival rates of larvae, rates of larvae which floated in the rearing water, and mortality rates of larvae which sunk to the bottom of the tank were investigated. The first stage zoeas floated in the upper layer of the rearing chamber showing positive phototaxis and negative geotaxis, however, almost all larvae of the later stages showed no reaction to a light stimulus and sunk to the bottom of the chamber. Larval floating rates and survival rates were improved by agitation and bath treatment with NFS-Na for rearing water; especially, survival rates significantly increased in the tanks with NFS-Na bath treatment.
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  • Age, growth and maturity of the Japanese sardinella Sardinella zunasi caught in Bisan Seto of the Seto Inland Sea, Japan
    NAOKI ODA
    2007 Volume 73 Issue 2 Pages 233-243
    Published: 2007
    Released on J-STAGE: April 03, 2007
    DOIhttps://doi.org/10.2331/suisan.73.233
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      Age, growth and maturity of the Japanese sardinella Sardinella zunasi were estimated from scale readings, observations and measurements of gonads. Specimens were collected by angling and set net as well as from commercial landings. Scale rings were found to be formed once a year from September to October. The matured are at least 9.5 cm in standard length for both sexes and the spawning season extends from June to September and its peak is in August. By applying the maximum likelihood method to the standard length-at-age data, we found that von Bertalanffy's growth equation with seasonal changes is a better fit than any other type of growth model, i.e. SLt=12.53[1-exp {-0.6254(F(t)+0.534)}] F(t)=t-(1/2π) sin 2π(t-0.259) for males, and SLt=13.42[1-exp {-0.4990(F(t)+0.713)}] F(t)=t-(1/2π) sin 2π(t-0.287) for females, where SLt is standard length in cm and t is age in year. The growth of females is statistically higher than that of males. SLs at which 50% of specimens attain maturity were estimated by logistic analysis as 10.11 and 10.32 cm for males and females respectively.
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  • Seasonal changes of two Sargassum species: S. yamamotoi and S. kushimotense (Fucales, Phaeophyceae) at Shibushi Bay, Kagoshima, Japan
    HIROMORI SHIMABUKURO, FUKUHISA HIGUCHI, RYUTA TERADA, TADAHIDE NORO
    2007 Volume 73 Issue 2 Pages 244-249
    Published: 2007
    Released on J-STAGE: April 03, 2007
    DOIhttps://doi.org/10.2331/suisan.73.244
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      The seasonal changes in size of two temperate Sargassum species (Phaeophyceae), S. yamamotoi and S. kushimotense, were studied in Shibushi Bay, Kagoshima, Japan. In addition, the line-transect method was conducted to describe their population characteristics and the vertical distribution of the seaweeds. Both species were found on rocky shores in the upper subtidal zone (1.0 m to 2.5 m in depth), and they were never observed in sand and intertidal zones. Maximum lengths were observed in April with 244.0 cm for S. yamamotoi and 194.6 cm for S. kushimotense. They decreased in size from May through August after the reproductive structures matured. Regenerated shoots and newly grown germlings were observed in September and they increased in size from October through March. The maximum density of each population was observed in April with 20 shoots m-2 for the former and 90 main branches m-2 for the latter. However, the biomass of each species in that month was almost the same: 1752 g dry weight m-2 for the former and 1782 g dry weight m-2 for the latter.
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  • Effects of release strategy, CPUE and temperature on the total length at recapture of hatchery-produced ocellate puffer Takifugu rubripes in Ariake Sound
    YASUHARU MATSUMURA
    2007 Volume 73 Issue 2 Pages 250-255
    Published: 2007
    Released on J-STAGE: April 03, 2007
    DOIhttps://doi.org/10.2331/suisan.73.250
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      This study was conducted to examine the effects of release time, release size, release site, quality of seeds, CPUE of young-of-the-year and water temperature of the habitat on the growth of hatchery-produced ocellate puffer Takifugu rubripes released in Ariake Sound. The effects of seven factors on the fluctuations of the total length at recapture on November 1 (Y) of 23 release groups of seeds released based on the data of mark-recapture experiments from 1991 to 1995 and from 2000 to 2002 were examined by multiple regression analysis. The factors were as follows: the date of release in July (X1), total length at release (X2), release site (X3), CPUE (X5) and average surface water temperature of the habitat in July and August (X6) and in September and October (X7). The relationship of total length to these factors was follows:
      Y=-1.14X1+0.49X2-6.03X3+0.54X5-2.60X6+1.87X7+211.69
    The regression was significant at the 1% level. The calculated values of the total length follow the trend of fluctuations of the observed values. Thus, it is concluded that is necessary to release hatchery-produced ocellate puffer early in July and at a large size in Isahaya Bay and the innermost area of Ariake Sound to maximize the total length at recruitment.
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  • Reproductive ecology of the neptune whelk Neptunea polycostata with special reference to maturity size, reproductive cycle, and sex ratio
    KATSUAKI FUJINAGA, YASUTAKA OYAMA
    2007 Volume 73 Issue 2 Pages 256-262
    Published: 2007
    Released on J-STAGE: April 03, 2007
    DOIhttps://doi.org/10.2331/suisan.73.256
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      The reproductive ecology of the neptune whelk, Neptunea polycostata, was investigated in Erimo, Hokkaido, from April 2000 to April 2001. Special emphasis was placed on maturity size, reproductive cycle (seasonal change in body organ index), and sex ratio. The sexual maturity size was 120-130 mm shell height in the male and 150-160 mm shell height in the female. The main copulation period was surmised to be from February to May. On the other hand, spawning was estimated to take place from March through August. Sex ratio changed seasonally. The shell height frequency distribution differed between male and female. From the data that the proportion of males sharply decreased after the maturity size of females (155 mm in shell height), the difference is considered to be also caused by the difference in mortality rate between male and female, besides the difference in growth between the two sexes.
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  • Estimation of mortality coefficient of flathead flounder Hippoglossoides dubius from tag recoveries in the western Sea of Japan
    ATSUSHI YAMASAKI, NAOKI YAGISHITA
    2007 Volume 73 Issue 2 Pages 263-269
    Published: 2007
    Released on J-STAGE: April 03, 2007
    DOIhttps://doi.org/10.2331/suisan.73.263
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      In order to estimate the mortality coefficients of flathead flounder Hippoglossoides dubius in the western Sea of Japan, a total of 2,928 tagged ones were released in the waters off Kyoto Prefecture in April 1994, 1995, 1996 and 1997. Using the maximum likelihood method with the recoveries every 1-fishing year term after released in each tagged group, total mortality coefficient was estimated to be 0.596 year-1 for 1994, 1996 tagged groups, and 0.455, 0.835 year-1 for 1995, 1997 tagged groups. Assuming appropriate values of survival rate just after release and rate of reporting of tag recoveries, ranges of fishing coefficient (Ft) and natural mortality coefficient (Xt) for tagged groups were estimated to be 0.159-0.393 year-1 and 0.236-0.449 year-1, respectively. It was suggested that high values of dispersion diminishing coefficient are contained in Xt.
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  • Contribution of hatchery-reared red sea bream Pagrus major to the commercial landings in Kagoshima Bay, Japan
    HIROTOSHI SHISHIDOU, SHUICHI KITADA
    2007 Volume 73 Issue 2 Pages 270-277
    Published: 2007
    Released on J-STAGE: April 03, 2007
    DOIhttps://doi.org/10.2331/suisan.73.270
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      Stocking effectiveness of red sea bream Pagrus major in Kagoshima Bay was estimated based on fish market surveys from 1989 to 2004. Mixing rates of nostril deformity fish, a characteristic of hatchery reared red sea bream, in fish investigated were 8.0-73.5% in number from 1989 to 2004. Estimates of recapture rate of up to 8+ year-old fish for releases from 1989 to 1995 were estimated at 2.6-12.2%. Economic efficiency for these releases was evaluated at 1.4-10.4. The recent decrease in recapture rates and economic efficiency was considered to be caused by some technical problems such as dwarf size at release without cage rearing around release sites due to budgetary cutbacks.
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  • Post-stocking dynamics of landlocked ayu Plecoglossus altivelis traced by a mitochondrial SNP marker
    HIROSHI IWATA, HIROHIKO TAKESHIMA, YASUHIKO TAGO, KATSUTOSHI WATANABE, ...
    2007 Volume 73 Issue 2 Pages 278-283
    Published: 2007
    Released on J-STAGE: April 03, 2007
    DOIhttps://doi.org/10.2331/suisan.73.278
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      We developed a novel single nucleotide polymorphism (SNP) marker on the control region of the mitochondrial genome of the ayu Plecoglossus altivelis; the marker can distinguish nucleotides A or G at a specific nucleotide site at which amphidromous and landlocked stocks of ayu are differentiated by different predominant nucleotides. The mitochondrial SNP marker was used to genetically trace landlocked ayu fish released into the Sho River (Toyama Prefecture) which was also inhabited by a native amphidromous population. Larvae, juveniles, and adults were collected throughout a year from the fluvial and marine habitats within and around the river, and subjected to DNA analysis. Mixing rate of landlocked stock was estimated for each life-stage on the basis of the frequency of the specific nucleotides at the SNP site. Though the estimation suggested considerable loss of landlocked ayu after release, mixing of drifting larvae reproduced by females of landlocked ayu was traced in the early spawning season. However, no evidence of survival in the offspring of the landlocked form was found from fish in the marine stage. The landlocked ayu was confirmed to be ineffective in the stock enhancement by releasing.
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