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Volume 37, Issue 4
Displaying 1-14 of 14 articles from this issue
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Hiromi OHTA, Takahiro MATSUBARA, Kazushi IMADA1989 Volume 37 Issue 4 Pages 235-239
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSFor artificial fertilization in salmonids, the artificial coelomic fluid (ACF) consisting of 152.6 mM NaCl, 3.5 mM KCl, 2.3 mM CaCl2, 0.7 mM MgCl2, and 5 mM NaHCO3, which corresponds in ionic constituents to the coelomic fluid (CF) of salmonids, has been used to wash off yolk contaminants from eggs to raise the fertilization rate. For the purpose of improving the isotonic solution, motility of spermatozoa of the masu salmon, Oncorhynchus masou, was compared between CF and ACF.
The time until all spermatozoa had ceased their forward movement was longer in ACF (346.5±16.4 sec) than in CF (263.5±15.8 sec), while the percentage of motile spermatozoa was significantly higher in CF than in ACF during the time from 15 to 120 sec after dilution. The speed of movement of spermatozoa was also higher in CF than in ACF at 30 and 60 sec after dilution. The results indicate that a relatively small number of spermatozoa could continue their forward movement for a long time in ACF. The moving distance index, which was calculated from the total amount of the mean velocity × time × % motility, in ACF was about one-half that in CF. It is concluded that ACF of masu salmon lacks some element, which favours the motility of spermatozoa in CF.View full abstractDownload PDF (2674K) -
Kinuko ITO, Susumu YOSHIDA, Ayako SUZUKI, Teiji KARIYA1989 Volume 37 Issue 4 Pages 241-246
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
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Riichi KUSUDA, Hiroyuki NAGOYA, Masami HAMAGUCHI1989 Volume 37 Issue 4 Pages 247-251
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSChanges in serum of bluefin tuna Thunnus thynnus with growth were studied by cellulose acetate membrane, polyacrylamide gel and agarose gel immunoelectrophoresis to clarify the immunological properties of the fish. The level of total serum protein was not related to the growth of bluefin tuna, however, the composition changed with growth. Some components of serum protein increased with sizes over 25 to 30 cm of fork length and 0.55kg of body weight.View full abstractDownload PDF (3929K) -
Moritsugu YONAMINE1989 Volume 37 Issue 4 Pages 253-257
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
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Minoru TANDA1989 Volume 37 Issue 4 Pages 259-265
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe starvation resistance of hatchery-reared flounder Paralichthys olivaceus was studied in rearing experiments. The sizes of fish used in these experiments were 20mm-100mm in total length. It was estimated that the irreversible point of the 23.4mm TL group was about 8 days without food. Death from starvation occurred earlier in the fish of smaller size, ie the mean survival days were prolonged in proportion to the increase of body length. The relationship between mean survival days and total length was showed by the following formura:
D=0.593×L-2.82 (D: mean survival days, L: total length in mm) .
Based on the supposition that the irreversible point was about 80% of the mean survival days, we estimated the days of permition in starved condition from this formula: 7.2 days in 20mm TL and 12.0 days in 30mm TL.
The 7 days of starvation affected the growth rate of juveniles in the 28.2mm TL group. The growth rate of the group which resumed feeding after 7 days of starvation was 0.97mm per day while that of the group which resumed after 3 days of starvation was 1.56mm per day.
The relationships between body length and body weight were showed by the two formulae:
(1) BW (mg) =0.0619×BL (mm) 2.380
(2) BW (mg) =0.0493×BL (mm) 2.663
The former is based on length and weight at death in a starved condition and the latter shows the normal condition. From these formulae we estimated that death due to starvation occurred when the body weight of juveniles was about half the normal weight.View full abstractDownload PDF (770K) -
Nobuhiro SUZUKI, Nobuo SAKURAI, Takuro SUGIHARA1989 Volume 37 Issue 4 Pages 267-274
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe underyearling fish of the oriental body Acanthogobius flavimanus in reproduction under laboratory condition grew to a mature size and sexual characters appeared within about a year after artificial insemination. While the fish exhibited an apparent ovarian maturity under such natural condition as water temperature from 14 to 11°C, the subject did not appear under a water temperature of 20°C.
To clarify the effect of water temperature on the gonadal maturation of this species, the changes in GSI and gonadal histology of the adult fish caught from the Odawa Bay, in Kanagawa Prefecture were examined for 52 days from November 1987 to January 1988 under the two water temperature conditions. Female fish GSI increased during the period and GSI of the fish in rearing under such natural condition as water from 14 to 11°C reached especially a high value. The ovaries have been occupied with large yolk globule stage oocytes. Under a water temperature condition of 20°C, the oocytes underwent regression. On the other hand, GSI values of males increased during the period and each GSI value in the two water temperature conditions was almost equal. In testicula histology of both conditions, numerous sperms were present in the lumens.
These facts suggest that water temperature plays an important role in ovarian maturation of this species.View full abstractDownload PDF (5263K) -
Shigehisa YAMASAKI, Hachiro HIRATA1989 Volume 37 Issue 4 Pages 275-280
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSRelationships between ammonium, nitrate, and organic nitrogen concentration in the culture medium of Nannochloropsis sp. (marine Chlorella) was studied in order to know the depletion of the nutrients by recycling process in an artificial ecosystem culture of rotifer. Desorption rate of ammonia from the culture medium to air due to aeration was also estimated to observe nitrogen budget of the culture. In both Exp. 1 and 2, ammonium sulphate and urea were mixed into 20‰ salinity natural filtered seawater as medium. Whilst, in Exp. 3, shark silage was used as nutrient. Nannochloropsis sp. was inoculated initially at 2×106 cells/ml. Desorption of ammonia was determined at pH values of 6.5, 8, 9, and 10.
The reduction of the ammonium concentration was more rapid than other types of nutrient. Decreasing concentration of organic nitrogen and nitrate were abserved once the ammonium concentration was lower than 100 μg-at/l. The percentage of organic nitrogen increased up to 80-85% of the total nitrogen and became constant on the 5-7th day of the culture period. Desorption rate of ammonia rose exponentially as pH increased. Desorption of ammonia within the first 5 days of the culture experiment of Nannochloropsis sp. was 0.9%in average of the initial nitrogen content of the culture medium. It could be considered that the nitrogen concentration which was required to maintain high nitrogen content of Nannochloropsis sp., was existed.View full abstractDownload PDF (778K) -
Masaru AMIO, Tatsuo HAMANO, Hideo HAMASAKI, Takashi HANADA, Hirotoshi ...1989 Volume 37 Issue 4 Pages 281-288
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSSpirochete bacteria of Cristispira were found to be present in the crystalline style of 26 bivalves, from intertidal and freshwater habitats, and included commercially important species. The number of Cristispira per style (NC) and their density in numbers per 1mm3 of style volume (DC), together with length of style (LS) and body fatness (FA) (calcufated as 100×meat wet weight/shell weight), were investigated as possible indices indicating the vitality of bivalves. NC, DC, and LS for a coastal clam Ruditapes philippinarum decreased in low salinity media where the vitality of this species declines. However, FA increased by osmosis. In a freshwater clam Corbicula leana, NC and DC rapidly decreased in a low dissolved oxygen medium (20% of saturated oxygen tension) which is unfavourable for this animal, though LS and FA were unchanged. Correlation coefficients for these vitality indices of R. philippinarum and a direct measure of vitality, the degree of burrowing into a sand bed, were comparatively high (rs=0.43-0.51) except for LS (r=0.32) . Of the four indices, DC was most suitable for indirectly indicating the vitality of bivalves. Further NC and FA would also be useful indicators of vitality when clams of similar sizes are studied in stable and favourable environments.View full abstractDownload PDF (1012K) -
Katsumi HIRANO, Yutaka SAKAI, Masato AKAZAKI1989 Volume 37 Issue 4 Pages 289-296
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSOccurrences of fish larvae and juveniles were examined from April to November, 1985 in the estuary of Kaeda River, Miyazaki Pref., Japan. Temperature and salinity varied in 18.2-29.6°C and 20.30-34.35‰, respectively. The fish collected from the estuary totaled 1, 890 specimens which are composed of 31 species. Predominant species were Mugil sp., Sicyopterus japonicus, Favonigobius gymnauchen, Gobius sp. 6, Gerres oyena and so forth, which were found from spring to summer. The collected fish were divided into three groups by change of mean total length and the period of their occurrence: Group A, species which the mean total length varied in every month; Group B, did not vary in every month; Group C, found only once throughout the investigation. Further, the fish were divided into four groups by environmental complexes: Group I, species which were found in low temperature and salinity; Group II, in high temp. and low sal.; Group III, in high temp. and slightly high sal.; Group IV, in low temp, and high sal. A complex fish founa was found especially during the June and August with a high diversity index. The fauna was found relatively similarly through mid-summer to early autumn.View full abstractDownload PDF (722K) -
Takuya OHTANI1989 Volume 37 Issue 4 Pages 297-301
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSZoeae of the fiddler crab, Uca arcuata, were kept until the metamorphoses to the juvenile crabs. The egg size was 0.26 to 0.30mm in the diameter, which is relatively larger one of its kinds in the identical genus. The zoeae born from one female totaled to 51, 000 to 64, 000 in the number. I fed Brachionus to the 1st-3rd stage zoeae, and Artemia nauplii from the 3 rd zoea stage to the swimming megalopa one. An artif ical food was given to the megalopae after their landing. The zoeae took 11 to 19 days (5 substages) for the molt to the megalopae. The metamorphoses to the juvenile crabs occured 10th to 16th day of the megalopa stage. When the exposed mud-substrate to the air was set up in the rearing tanks, the swimming megalopae spent 4 to 5 days within the water and then landed to dig the burrows for the molt to come. However, unless the swimming megalopae faced the exposed mud-substrate to the air, they were not molted to the juvenile crabs, although they survived for 28 days within the water.View full abstractDownload PDF (559K) -
Relationships between LC50 values and exposure period to pesticides in fish toxicity testYasuhiro NISHIUCHI1989 Volume 37 Issue 4 Pages 303-305
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESS -
Changes in susceptibility of carp to several pesticides with growthYasuhiro NISHIUCHI1989 Volume 37 Issue 4 Pages 307-309
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESS -
Hachiro HIRATA1989 Volume 37 Issue 4 Pages 311-316
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSWater pollution in aquaculture has become a serious problem all over the world, recently. We have then studied how to maintain the homeostasis of ecosystem in hatcheries and coastal fish farms. Some laboratory and field studies conducted by our group are briefly introduced in this paper.
A feedback culture system was conducted for maintaining the homeostasis of ecosystem in the culture of zooplankton (Brachionus plicatilis and Tigriopus japonicus) . In this respect, marine algae (Chlorella hirataii and Enteromorpha intestinalis) were cultured using excess nutrients produced in the zooplankton culture. Homeostasis of ecosystem in the culture waters was maintained for 485 days. The ratio of plant and animal harvested in this culture was calculated to be 2 : 1. This means algae can be harvested 2 times higher than the cultured animals.
In the field works, results of the evaluation conducted throughout the area were publicized in a map form on dissolved oxygen content (DO map) which is resemble to the weather map and it environmental standard score (ESS), to inform the fishermen on the environmental status of their culture area. This evaluation is quite strict judgement on fishermen awareness on keeping a good water environment in their culture area. Even though, many were reluctance at the beginning, but they are getting familiar and realize about it consequences for a better cultured fish prices.
In order to remove the excess nutrients from the seawater, 56 cages were placed in the fish farm, and sterile Ulva sp. was cultured in these cages.View full abstractDownload PDF (649K) -
1989 Volume 37 Issue 4 Pages 317-326
Published: December 20, 1989
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSDownload PDF (1156K)
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