Aquaculture Science
Online ISSN : 2185-0194
Print ISSN : 0371-4217
ISSN-L : 0371-4217
Volume 51, Issue 3
Displaying 1-16 of 16 articles from this issue
  • Ken-ichi WATANABE, Tatsuya HOSHO
    2003 Volume 51 Issue 3 Pages 257-262
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    The stock of ayu, Plecoglossus altivelis in the Yoshino River consists of three types, the amphidromous hatchery form, landlocked form derived from Lake Biwa and the native amphidromous form. The number of the native amphidromous form was estimated by analyzing the frequency distribution of the rank line scale number of the upper lateral line. Each frequency distribution of the three types was normally distributed and each average was significantly different from the other types. By fitting the normal distributions to the frequency distribution of the rank line scale number of the caught samples in which the fish from three types were mixed, the ratio of the native amphidromous form was calculated. The Marqualdt method was used for fitting the normal distributions. The number of the native amphidromous form was calculated from the ratio and the number of released hatchery form and landlocked form. The estimated number of the native amphidromous form from year 1998 to 2002 was 3, 938, 000, 17, 147, 000, 16, 934, 000, 24, 630, 000, and 32, 628, 000, respectively. The method adopted here is considered to be effective for the stock abundance estimation in big rivers such as the Yoshino River.
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  • Kensaku AZUMA, Nobuo HORIKI, Nobuhiko TANIGUCHI
    2003 Volume 51 Issue 3 Pages 263-271
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    The annual stock fluctuation of ayu, Plecoglossus altivelis altivelis, was investigated through their larval and juvenile stage from November to May in the 1999, 2000 and 2001 year groups both in the coastal waters and in the Hidaka River of the central Wakayama Prefecture. The catches of juvenile ayu in coastal waters and the number of ayu migrating upstream the Hidaka River increased with the year group from 1999 to 2001. Thus the 2001 year group was considered to be a bumper year. Ayu larvae in the 2001 year group occurred abundantly in the surf zones around the mouth of the Hidaka River, and their sizes were larger than those of the other two year groups. These findings suggest that the amount of larval recruitment and the following larval growth rate in surf zones should correspond to the level of the stock of ayu population. We suppose that high larval mortality of ayu in the sea could occur before recruitment to surf zones, and extent of the mortality would be an important determinant for the year-class strength.
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  • Shinji KIRIHARA, Toshiki NAKAMURA, Masahiro NOTOYA
    2003 Volume 51 Issue 3 Pages 273-280
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    Relationship between the standing crop of Laminayia japonica and water temperature was investigated at the coast of Shiriyazaki, Shimokita Peninsula, Aomori Prefecture. Growing densities of the sporophytes of L.japonica were calculated from the number of plants at 53-70 points at depths of 2.5 m, 5 m, 10 m, 15 m, and 20 m from June to July of each year from 1984 to 2002. The water temperature was measured at a depth of 5 m. The significant negative relationship between their densities and the water temperature of January to March by 1% level was accepted. Among those, the growing densities of 1st year and 2nd year sporophytes (L1 and L2) indicated a value with the most significant simple correlation of -0.889 and -0.787, for the water temperature of the 5th pentad in January (Tc5) and of the 3rd pentad in March of the previous year (Tp15), respectively. As a result, applying these relationships to exponential regression equations, can be expressed as follows:
    L1=exp (11.600-1.024×Tc5) R=0.957
    L2=exp (7.523-0.983×Tp15) R=0.939
    The biomass of the 1st year sporophytes and the 2nd year harvestable sporophytes can be predicted from the water temperature of such period.
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  • Shinji KIRIHARA, Yoshikazu FUJIKAWA, Masahiro NOTOYA
    2003 Volume 51 Issue 3 Pages 281-286
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    Zoospore germlings of Kjellmaniella cyassifolia Miyabe were cultured at various temperatures (5, 10, 15, 20, 25°C) and light intensities (10, 20, 40, 80μmol/m2/s) under a photoperiod of 14 L: 10 D (light: dark) in a modified Grund medium for 6 weeks. Effects of temperature (5, 10, 15, 20, 25°C) on maturation of the gametophytes and growth of sporophytes were observed at a light intensity of 20μmol/m2/s for 13 weeks. Rapid growth of gametophytes were observed at 20°C and 80μmol/m2/s. However, the gametophytes did not mature and produce sporophytes at 20°C regardless of light intensities. Sporophytes were produced from the female gametophytes after fertilization at 5-15°C . Rapid growth of sporophytes in a flask and an aquarium was observed at 5°C. Sporophytes did not grow at 20°C and 25°C. The highest temperature for survival of the gametophytes and sporophytes was similar to those of Laminaria species in Hokkaido.
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  • Yukihiko SERISAWA, Hiroshige MURAKAMI, Jiro TANAKA, Masakazu AOKI, Yos ...
    2003 Volume 51 Issue 3 Pages 287-294
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    In April 2001, sporophytes of Ecklonia cava and Eisenia bicyclis (Laminariales, Phaeophyta) were collected from within two haphazardly-placed 1 m2 quadrats at each depth of 0, 2.5, 5, 10, 15, 20 and 23 m off Touji, Shimoda, Shizuoka Prefecture, Japan. The combined biomass of E. cava and E. bicyclis was 0.13-1.50 kg d.w./m2, maximal at 0-2.5 m depth and minimal at 23 m depth. Density of E. cava gradually increased with the depth from 20 ind./m2 at 2.5 m depth to 49 ind./m2 at 20 m depth. Conversely, the density of E. bicyclis decreased with the depth from 31 ind./m2 at 0 m to 4 ind./m2 at 2.5 m depth. E. cava and E. bicyclis co-occurred at 2.5 m depth. The mean values of stipe length and diameter of E. cava were minimal at 23 m depth (17.2 cm and 11.0 mm, respectively) and maximal at 2.5 m depth (91.5 cm and 23.2 mm, respectively) . The mean values of primary blade length of E. cava ranged 22.0-29.1 cm irrespective of the depths. The mean values of stipe length, stipe diameter and arm length of E. bicyclis were 45.3 cm, 27.1 mm and 6.8 cm, respectively. Other seaweeds surrounding or within the marine forest were also surveyed at each depth. A total of 68 species were identified: 8 Chlorophyta, 26 Phaeophyta, and 34 Rhodophyta. The number of species was greater at≥15 m depth.
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  • Katsunori TACHIHARA, Emi OBARA
    2003 Volume 51 Issue 3 Pages 295-306
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    The Mozambique tilapia, Oreochromis mossambicus is one of the species introduced to Okinawa Island. This species breeds widely in the rivers of the island. In order to understand the biological aspects of O. mossambicus under the natural conditions of the island, a detailed observation of early morphological development was done under rearing conditions. The development of O. mossambicus was studied; it consisted of an embryonic phase of approximately 88 hours and 30 minutes, a free embryonic phase of about 12 days, followed by the juvenile period. The embryo became free-swimming on the sixth day of the free embryonic phase. The osteological development using enzyme-cleared specimens indicated that after reaching the juvenile stage, development of almost basic bones was complete 25 days after hatching.
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  • Katsunori TACHIHARA, Emi OBARA
    2003 Volume 51 Issue 3 Pages 307-313
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    The Mozambique tilapia, Oreochromis mossambicus is a species intentionally introduced as a source of low cost protein or as bait fish for skipjack angling in Okinawa Prefecture. This species has recently been found to breed widely in natural rivers of the Ryukyu Islands. The growth and life history of O. mossambicus were studied between May 1996 and August 1997 at the Genka River on Okinawa Island, Japan. Analysis of the marginal increments of 263 otoliths showed an annulus was formed between May and July, corresponding to the reproductive periods. Maximum ages of 14 years for females and 8.5 years for males were obtained for the Genka River population, and patterns by the von Bertalanffy formula growth were described as Lt=276.9 {1-exp (0.63 (t-0.38) ) } for males and Lt=237.6 {1-exp (-0.26 (t+1.32) ) } for females, respectively.
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  • Tomoyuki NAKAMURA, Norio ODA
    2003 Volume 51 Issue 3 Pages 315-320
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    The Japanese bagrid, Pseudobagrus tokiensis, which is a vulnerable species in Japan, was observed to make spawning migrations into a paddy field ditch in the Naka River system, Tochigi Prefecture, central Japan in 1999 and 2000. A lot of fishes ascended the ditch, of which P. tokiensis accounted for 17.7 and 15.4% in number in 1999 and 2000, respectively. Pseudobagrus tokiensis ascended the ditch from early May to late August and the number of them was highest in early July. For mature P. tokiensis, the body size was larger in males than females and the sex ratio was biased to females. Most P. tokiensis ascended the ditch during the night and the number of them increased on rainy days. These results show that paddy field ditches may play a role as the spawning habitat of P. tokiensis and their spawning migration occurs nocturnally, being stimulated by precipitation.
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  • Ken-ichi YAMAMOTO, Takeshi HANDA, Kenji FUJIMOTO
    2003 Volume 51 Issue 3 Pages 321-326
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    The differences in tolerance to low-salinity among Red, Blue and Black (color pattern) of the Japanese common sea cucumber, Apostichopus japonicus were examined from the ventilation in the respiratory tree. Red, Blue and Black showed no effect of low-salinity to 30‰, because the ventilation remained almost constant. When the salinity decreased below 30‰, the exhalation and inhalation volume per stroke, and the ventilation volume per min decreased in Red, Blue and Black, though the respiration frequency per min and the inhalation frequency per one cycle of ventilation were similarly almost constant. From these results, it was judged that there was fundamentally no differences among Red, Blue and Black in the ventilation. However, the effect of salinity on ventilation cessation was higher in Red than in Blue or Black.
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  • Seiji KATAKURA, Morinobu OHTA, Masato JIN, Yasunori SAKURAI
    2003 Volume 51 Issue 3 Pages 327-335
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    Captive juvenile walleye pollock, Theragra chalcogramma, were immersed for 24 hours in different solutions of oxytetracycline (OTC), alizarin complexone (ALC), and alizarin red S (ARS) to determine which solutions can be used to mark their otoliths. Otoliths were successfully marked with a 25 ppm solution of ALC and 200 to 1000 ppm solutions of ARS, but, they were not marked with 100 to 400 ppm solutions of OTC. Otolith, scale, dorsal-fin ray, and subopercle marks were identified in captive yearlings one year after they were marked with ALC and ARS. Observations on otolith marks showed that annual ring patterns differed between captive and wild fish. Captive age-1 fish, which were reared under stable water-temperature, photoperiod and feeding conditions for one year, and had higher growth rates than wild fish, did not form an annual ring. Considering its low toxicity, good quality of marks, and relatively low cost, ARS is considered the most reliable immersion method of the three analyzed for marking juvenile walleye Pollock.
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  • Masayuki YAMAMOTO, Motohide TOCHINO
    2003 Volume 51 Issue 3 Pages 337-342
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    To understand juvenile fishes and halfbeak Hyporhamphus sajori eggs removed by the marine environment-improving ship in the central Seto Inland Sea, we examined the quantity and composition of floating objects. The annual amount of floating objects removed by the ship was about 1, 300 m3 from April 1995 to March 1999. The volume increased in spring, peaked in July, and decreased in autumn and winter. The major items of the floating objects were seaweeds and sea-grass in spring and sea-grass and reed Phragmites australis in summer. Juvenile fishes were hardly removed by the ship. The halfbeak eggs clung to floating seaweeds appeared from April to June. The number of eggs per kg of marine-algae was 500-16, 000. The weight of marine-algae removed from April to May was about 41, 000kg. These results suggested that about 320 million halfbeak eggs per year can be removed by the ship.
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  • Koh-ichi SATOH, Masashi MAITA, Akira WAKATSUKI, Shinichi MATSUDA
    2003 Volume 51 Issue 3 Pages 343-348
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    Feeding experiments were conducted to establish the effective use of extruded pellet (EP) in the adult yellowtail, Seriola quinqueradiata. Fish were fed two types of commercial EP, medium fat type (CL 23%, EP-MF) and high fat type (CL 28%, EP-HF) during July to December. Two feeding trials were carried out during the years 2000 and 2001. Growth performance and feed utilization in these fish were compared with those of fish fed raw-fish diet. In the summer season when the water temperature rises above 24°C, the daily growth rates (DGR), daily feeding rates (DFR) and feed efficiencies (FE) in fish fed on the two pellet types were not different from those in fish fed on raw-fish diet. On the other hand, DGR of fish fed EP were significantly lower than that of fish fed the raw-fish diet in the fall season. Though the DFR in the EP-fed groups were significantly lower than that of the raw-fish fed group in the fall season, FE was not significantly different. Therefore, it was suggested that proper feeding regimes had to be developed to improve growth of fish fed EP in the fall season. There was no growth difference between yellowtail fed high and medium dietary lipid levels, thus no clear conclusion was made which lipid level is suited for adult yellowtail.
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  • Younseong HEO, Reiko FUSEYA, Masashi YOKOTA, Seiichi WATANABE
    2003 Volume 51 Issue 3 Pages 349-354
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    Horizontal starch gel electrophoresis was used to analyze the genetic variation and relationship between the Japanese swimming crab Charybdis japonica, C. annulata, C. feriata, C. miles, C. lucifera, C. anisodon, C. bimaculata and C. natator. Twenty one specimens of Ovalipes punctatus were collected from East China Sea to use as an out group in genetic relationship analysis. Sixteen allozymic loci of 11 enzymes were examined using muscle tissue. Gene substitution was found at 8 loci, AAT, G3PDH, GPI, IDHP-1, IDHP-2, LDH, MDH-1, and MDH-2 out of 12 loci in 8 Charybdis species. Genetic analyses showed that Nei's genetic distances were ranged 0.065-0.359 between C. japonica and genus Charybdis.
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  • Makoto HADO, Masanori OKAUCHI, Noboru MURASE, Yuzuru MIZUKAMI
    2003 Volume 51 Issue 3 Pages 355-360
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    The transient expression of β-glucuronidase (GUS) genes in protoplasts of Porphyra yezoensis was examined using the ribulose-bisphosphate-carboxylase/oxygenase (Rubisco) gene promoter. The DNA fragments which contained the Rubisco gene promoter sequences were ligated with the GUS gene of plant vector pBI 221. When these vectors were introduced into Protoplasts, dark blue cells could be detected after the histochemical assay for GUS activity. The GUS activity was also detected by quantitative assay with a chemiluminescent substrate. The effective expressions of the GUS gene were obtained under the electroporation conditions of 200 to 300 V field strength, 47 ms pulse length and 0.03μg/ml vector DNA concentration. The agarose culture of protoplasts was more effective than the liquid culture to obtain high expression rate of the introduced GUS gene. In addition, high expression rates of introduced genes were observed at 4 to 5 days after the electroporations. These results show some of the technical conditions for the transient expression of GUS gene in P. yezoensis.
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  • Takanobu GOTO, Hiroki SUGIYAMA, Hiroyuki FUNATSU, Yuko OSADA, Shusaku ...
    2003 Volume 51 Issue 3 Pages 361-362
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    Hepatic cysteinesulfinate aminotransferase activity was studied in fish. Fish liver homogenates were incubated with a reaction mixture containing cysteinesulfinate, 2-oxoglutarate, PLP, NADH, and lactate dehydrogenase for 15 min at 25°C. NADH oxidation was monitored at 340 nm and defined as the enzyme activity. The highest enzyme activity was observed in yellowtail followed by that in red seabream. The lowest level of activity was observed in bluegill. However, the enzyme activities were distributed over a narrow range from 115-430 nmol/min/mg protein. These observations suggest that transamination is a common pathway for cysteinesulfinate metabolism in fish.
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  • Tadashi ISSHIKI, Motohide TOCHINO, Taizou NAGANO
    2003 Volume 51 Issue 3 Pages 363-364
    Published: September 20, 2003
    Released on J-STAGE: March 09, 2010
    JOURNAL FREE ACCESS
    This paper aimed to report successful cases of treatment of Neoheterobothrium infection in Japanese flounder, Paralichthys olivaceus with 8% NaCl-supplemented seawater. In a hatchery in Kagawa Prefecture, Japan in 1999 and 2000, brood stocks of Japanese flounder underwent severe anemia. To maintain the seed production, the naturally infected flounder with the causative parasite, Neoheterobothrium hirame, were treated by 8% NaCl-supplemented seawater bathing for 5 min at 17 and 20°C, resulting in detachments of both immature and adult worms, and recovery from anemia in the host fish, with no death of the host fish during and after the treatment. These observations assumed that the NaCl-supplemented seawater bathing is an effective treatment of Neoheterobothrium infection in Japanese flounder.
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