Aquaculture Science
Online ISSN : 2185-0194
Print ISSN : 0371-4217
ISSN-L : 0371-4217
Volume 35, Issue 4
Displaying 1-9 of 9 articles from this issue
  • Nobuhiro SUZUKI, Nobuo SAKURAI, Takuroh SUGIHARA
    1988 Volume 35 Issue 4 Pages 203-212
    Published: March 01, 1988
    Released on J-STAGE: September 07, 2010
    JOURNAL FREE ACCESS
    The egg, and larval development of the gobioid fish called “Urohaze”in Japanese, Glossogobius olivaceus are carried out on August, 1986. Hatched larvae are reared for a period of 380days. The spawning period extended from the beginning of August to the mid of September. The ripe egg immediately after insemination is pear in shape, measuring 0.75-0.81mm in long axis and 0.29-0.38mm in short axis, which a boundle of the adhesive filaments at its basal end and a cluster of small oil globules. The number of ripe eggs per spawning is ca. 60, 000. The egg membrane elongated to form a perivitelline space when the inflation ceases 30 minutes after insemination. The egg altered ellipsoid in shape which measured about 2.61mm in long axis and about 0.46mm in short axis. The incubation period was about 79 hours at a water temperature of 22.4-26.3°C. Soon before hatching, the tail of larva never attached to the basal end region of the egg-shell. This character is not shared with larvae of many other gobioid fishes during embryonic development. The newly hatched larvae measured from 2.27-2.37mm in total length (TL), averaging 2.34mm in TL and swim freely in an aquarium. At yolk absorption, 6days after hatching, the larvae attained 2.29-3.10mm in TL and started to practice feeding on the small rotifer, 100-150μm in size. Eleven days after hatching, the larvae are averaged 4.16mm in TL, the caudal notochord flex at 45° and rudimental the second dorsal, anal, caudal and ventral fins are formed. Twenty-five days after hatching the larvae reached the juvenile stage at 7.72-8.88mm in TL and were found to carry the bottom-life.On the 45th days, all scales appeared on the body. A clear black band which cuts across from the mid of lower and upper jaws to the mid of facial region is characteristic at the immature fish stage. The fish grew to 126.05-164.50mm in TL and some individuals became mature in one year. Almost fishes seem to become mature in two years and die of spawning.
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  • Hideo YAMANOI, Teruyuki SUGIYAMA, Katsusuke KATAYAMA
    1988 Volume 35 Issue 4 Pages 213-222
    Published: March 01, 1988
    Released on J-STAGE: September 07, 2010
    JOURNAL FREE ACCESS
  • Hisashi KUROKURA, Nobuyuki KURODA, Shogoro KASAHARA
    1988 Volume 35 Issue 4 Pages 223-228
    Published: March 01, 1988
    Released on J-STAGE: September 07, 2010
    JOURNAL FREE ACCESS
    Short necked clams Tapes japonica were reared by means of feeding with the suspension of mud which were collected from tidelands at the mouth area of the Ashida river. The clams fed with the suspension could survive longer than 19days, though the longest duration of survival was 13days in clams without feeding. Similar effect could be obtained by feeding with the filtrate of the suspension. There were clear differences in the effect of feeding among the muds from 4 different stations at the river mouth area. These differences could explain the difference in recovery which were observed in the releasing test at each station.
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  • Nobuo HORIKI
    1988 Volume 35 Issue 4 Pages 229-235
    Published: March 01, 1988
    Released on J-STAGE: September 07, 2010
    JOURNAL FREE ACCESS
  • Munenori MIYAKAWA, Kiyokuni MUROGA
    1988 Volume 35 Issue 4 Pages 237-243
    Published: March 01, 1988
    Released on J-STAGE: September 07, 2010
    JOURNAL FREE ACCESS
    The aerobic bacterial populations and flora of cultured rotifer (Brachionus plicatilis) and its ambient water were investigated at Hiroshima Prefectural Fish Farming Center from October to November in 1985.
    In an outdoor tank (150m3) for rotifer culture, the numbers of bacteria in rotifers were 107-108CFU/g on ZoBell's 2216e agar, 106-107CFU/g on BTB teepol agar and those of the tank water were 105-106, 103-104CFU/ml, respectively. In an indoor tank (4m3, heated), almost the same numbers of bacteria as in the outdoor tank were detected both in rotifers and water.
    The numbers of bacteria of rotifers were decreased to one tenth or one hundredth by a bathing in sodium-nifurstyrenate (10ppm, 1h) which was made after harvesting. In another experiment, rotifers were medicated before inoculation and after harvest, but the final bacterial population could not be lessened further.
    Changes in bacterial flora of rotifers were investigated throughout the course of a culture. As the result, generic composition was found to be relatively stable, Pseudomonas (61.7%) and Moraxella (17.4%) being the dominant groups.
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  • Katsumi HIRANO, Hirotoshi KAWANO
    1988 Volume 35 Issue 4 Pages 245-252
    Published: March 01, 1988
    Released on J-STAGE: September 07, 2010
    JOURNAL FREE ACCESS
    The investigation was conducted on the size of a marine Chlorella cell exerted on the feed intake of Rotifers to obtain the following results.
    (1) The number of Chlorella cells did not almost increase during a light period but markedly increase during a dark period.
    (2) The average cell volume of Chlorella showed a large value of 10-18μm3 in the light period but became small in the dark period to show a value of 8-9μm3.
    (3) The average cell volume of Chlorella was 9.78μm3 when pH of culture water was 7.5-8.0 and 12.90μm3 when 9.0-9.5.
    (4) The feed intake quantity (cells/Rotifer/6 hr) of rotifers was 5200cells to Chlorella of 8μm3 and 8100cells to Chlorella of 12μm3.
    (5) When the average cell volume of Chlorella largely changed, the feed intake rate became lower and the maximum feed intake rate was 52.8% when the change rate was 106%.
    (6) The size of Chlorella always changed in a culture tank for the culture of rotifiers in the presence of Chlorella and it was considered that the feed intake rate of Chlorella, which had a proper size for rotifers, and a change rate of 106% was highest.
    (7) The density of rotifers and the average cell volume of Chlorella were participated in the feed intake quantity of Chlorella.
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  • Shigehisa YAMASAKI, Hachiro HIRATA
    1988 Volume 35 Issue 4 Pages 253-257
    Published: March 01, 1988
    Released on J-STAGE: September 07, 2010
    JOURNAL FREE ACCESS
    Optimum food consumption rate, which maintains lower pollution of culture water and higher growth rate of rotifer, was estimated on the basis of food energy distribution and water quality. Immediate dissolved oxygen demand (IDOD) was used as an indicator of the water quality.
    In the first experiment, rates of food consumption and growth were determined. Five aqualia with different density levels of marine Chlorella sp.; 0.5, 1, 3, 5, and 8×106 cells/ml, were prepared and maintained at the particular density by periodical addition of concentrated algae. Rotifers were inoculated at the density of 50ind/ml. In order to maintain the selected density, rotifers were harvested every morning. At the same time, 30% of the culture medium was changed. The rate of aeration was 400ml/min. Water temperature, salinity, pH and light were adjusted at 20±1°C, 20‰, 7.5 and 100lx (15L: 9D), respectively. The experimental period was 2 weeks with an acclimation time of 4 days.
    In the second experiment, oxygen consumption rate of rotifer and IDOD were determined at each of the previously determined food densities. A respirometer of automated type was used for the measurement. The duration of each recording cycle for the culture medium with and without rotifer was 30 min. IDOD was calculated by subtracting physico-chemical oxygen consumption of the DO probe, rubber stopper, and surface of the chamber from the recorded DO value. Each group of rotifers was cultured in a 5l conical tank, under the same environmental condition as that of the first experiment. Rotifers were acclimated to the experimental conditions for 4 days. After changing the culture medium with filtered sea water, DO was recorded for 24h.
    IDOD values related to culture age increased linearly with the regressive gradients being steeper at densities above 3×106 cells/ml. The growth rate of rotifer increased rapidly within the food densities between 0.5 and 3×106 cells/ml and became constant at higher densities. Energy loss values showed the same tendency as the growth rate. On the other hand, food conversion rate increased up to 3×106 cells/ml but decreased rapidly at higher algal densities. It can be deduced that above this density (3×106 cells/ml) water becomes polluted faster, due to an increase in energy loss. The optimum food consumption rate for L-type rotifer was estimated to be around 357% of the body dry-weight per day at the food density of 3×106 cells/ml. This value corresponds to about 70% of the saturated rate of food consumption.
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  • Mitsuyuki HORIUCHI, Akira KUWAHARA, Takehisa SOUMA, Minoru NAKATA
    1988 Volume 35 Issue 4 Pages 259-263
    Published: March 01, 1988
    Released on J-STAGE: September 07, 2010
    JOURNAL FREE ACCESS
    The availavility of ammonia water long-hour bath for the control of pseudodactylogyrosis in cultured eels (Anguilla japonica) was investigated.
    The parasites, Pseudodactylogyrus anguillae, obtained from the gills of infected eels were completely killed in vitro by 24h treatment of 15.6ppm ammonia at 25°C. Satisfactory anthelmintic effect was obtained when the infected eels were bathed in 15ppm ammonia for 18h at 25°C. The maximum safety concentrations of ammonia for bath on eels were 39.5ppm in two culture water at different pH (6.6 and 7.4) .
    The results in this study suggested that the ammonia water long-hour bath might be one of the effective methods for controlling pseudodactylogyrosis in eel culture ponds.
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  • Takeshi TABARU, Tsukasa NASU, Osamu ISHIBASHI
    1988 Volume 35 Issue 4 Pages 265-270
    Published: March 01, 1988
    Released on J-STAGE: September 07, 2010
    JOURNAL FREE ACCESS
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