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Volume 44, Issue 1
Displaying 1-17 of 17 articles from this issue
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Katsumi HIRANO, Yukio IWATSUKI, Fumitaka MIMURA, Masao YAGI, Shigeyuki ...1996 Volume 44 Issue 1 Pages 1-6
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe number of Ayu, plecoglossus altivelis going upstream through the central fishway of Iwakuma weir in the Gokase River, Miyazaki Prefecture, was investigated for 3 years. There were large differences in the numbers of fish moving upstream among the three years. However, the peak time of the upstreaming occurred at 14-18 o'clock during a period from the last ten days of April to the middle of May. Upstreaming was frequently observed when water temperature in the fishway was in the range of 15-20°C and the flow in the lower stream of the fishway was abundant. The numbers of upstreaming fish on fine days were larger than that on rainy days. Further, upstreaming fish were more numbers on the days near new moon than near full moon.View full abstractDownload PDF (549K) -
Benjamin J. GONZALES, Osamu OKAMURA, Nobuhiko TANIGUCHI1996 Volume 44 Issue 1 Pages 7-15
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSAdult Repomucenus huguenini were caught in the wild and allowed to spawn spontaneously in tanks. Spawning occurred almost every day, late in the afternoon and into the night, for 54 days. R. huguenini spawned within a restricted time (17: 00-21: 00) of the day at a relatively wide range of light intensity (2.5-105.0lux) . The eggs averaged 0.67 mm in diameter, being the same as that of congener R. beniteguri, but larger than that of confamilial P. enneactis. Hatching took place 18 h after spawning at 25.8-26.0°C in mid-autumn. The newly-hatched prolarvae measured 1.0 to 1.2 mm TL (mean, 1.03 ± 0.072 mm) . Most of the one-day-old prolarvae had an elongated caudal fin membrane considered to be species specific specialized larval character.View full abstractDownload PDF (906K) -
Izumi SAKURAI, Shigeru NAKAO1996 Volume 44 Issue 1 Pages 17-23
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe spatial distribution of planktonic larvae of the Japanese surf clam Pseudocardium sachalinensis at Tomakomai, Hokkaido, was studied in relation to the coastal water conditions. The umbo stage larvae, with 0.20-0.24-mm-long shells, were distributed mainly in the 5 m depth layer 400-1, 200 m off-shore. The full-grown stage larvae, with shells>0.24 mm long, were distributed patchily near the bottom 800-1, 600 m off-shore, and there were significant positive correlations between the larval density and water salinity or density. The relationship between the mean number of larvae and the coastal water conditions suggested that the major factor responsible for the appearance of the full-grown stage larvae was the existence of water with a salinity>33 or density>1025.5kg/m3.View full abstractDownload PDF (812K) -
Shuuji TSUJI, Masahiro MUNEKIYO, Masashi ITANI, Akio DOUKE1996 Volume 44 Issue 1 Pages 25-30
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESS -
Mikio NAKAMURA, Shigeru YASUGI, Fumiko TAKAHASHI, Akira SHINAGAWA, Shi ...1996 Volume 44 Issue 1 Pages 31-35
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe brackish water bivalve, Corbicula japonica, was found to tolerate exposure to salinities ranging from 0 to 35 psu at 15°C. Gradual exposure to different salinities resulted in equilibration of the body fluid with the external medium, indicating that this species is a euryhaline osmoconformer.
Salinities ranging from 1.5 to 22 psu were not lethal for C. japonica acclimated to either 10°C or 25°C. At a high salinity of 32 psu, bivalves survived a longer period of time after acclimation to low temperature as compared to high temperature. In addition, adults were more tolerant of concentrated media than juveniles.View full abstractDownload PDF (580K) -
Stefanos PALATZIDIS, Shigehisa YAMASAKI, Hachiro HIRATA, Takehiko IMAI1996 Volume 44 Issue 1 Pages 37-43
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe use of different green seaweeds (Ulva pertusa Kjellman, Ulva fasciata Delile, and Enteromorpha intestinalis Link) for the culture of sea hare Aplysia juliana from immaturity to adult stage was examined during a period of 130 days under laboratory conditions. Specimens at the start of the experiment ranged in size from 0.07 to 0.08 g wet weight. All the seaweeds tested were suitable foods for the sea hare and promoted growth rates: for E. intestinalis, 0.14 g/day; for U.fasciata, 0.12 g/day; and for U. pertusa, 0.10 g/day. Spawning activity was first detected on the 15th, 18th and 29th days of culture when Aplysia were fed E. intestinalis, U. fasciata and U. pertusa, respectively. Total egg production was higher using E. intestinalis (25.1 g in dry weight per animal) when compared to Ulva (20.8 g for U. fasciata and 10.8 g for U. pertusa) . A positive correlation was found between temperature and egg production after the first 10 days of egg-laying. Food consumption of Ulva by Aplysia was significantly (p≤0.01) higher than that of Enteromorpha. Consumption rate of U. pertusa by Aplysia was 22.4 % of its mean body weight per day, whereas it was 14.6 % for U. fasciata and 8.5 % for E. intestinalis. The following conclusions were obtained from the results: 1. food consumption followed the order U. pertusa>U. fasciata>E. intestinalis; 2, the gross assimilation efficiency values of A. juliana for each algal diet including the total weight of eggs produced in the measure of total growth were 31.6 % for Enteromorpha, 18.9 % for U. fasciata and 10.1 % for U. pertusa; 3. A. juliana has potential to control the plagues of macro algae such as Ulva and Enteromorpha, usually present in semi-intensive or extensive aquaculture facilities.View full abstractDownload PDF (787K) -
Shigenori SUZUKI, Atsushi OHNO1996 Volume 44 Issue 1 Pages 45-52
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe population dynamics of the S-type rotifer, Brachionus plicatilis rotundifarmis, was investigated in the laboratory. Eggs were obtained by strongly stirring egg-carrying females. The eggs were then inoculated in a 30-l polycarbonate tank containing 20-l seawater at a density of 30 eggs/ml. Unicellular algae, Nannochloropsis oculata, was given as food organism for rotifers hatched in the tank. Observation of the propagated rotifer population was carried out every 3 hrs until 120 hrs after the time the eggs were inoculated. The average life span of the rotifer population was estimated to be 43.1 hrs; interval from hatching to first spawning, 21 hrs; and time required for hatching, 11-12 hrs. The mortality was relatively low from hatching to sexual maturation, increasing repidey after intensive spawning.View full abstractDownload PDF (779K) -
Shigehisa YAMASAKI, Hachiro HIRATA1996 Volume 44 Issue 1 Pages 53-57
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSDissolved inorganic carbon, accumulated in the rotifer culture, was measured to ascertain the possibility of recycling it in an ecosystem culture. In the ecosystem culture, the marine rotifer Brachionus plicatilis is used as consumer whereas the alga Nannochloropsis sp. served as primary producer. Those organisms are cultured in separated tanks. The experiment was performed employing rotifer and Nannochloropsis, individually as well as in combination, with and without aeration. The treatments included: 1) rotifer + Nannochloropsis + aeration; 2) rotifer + Nannochloropsis; 3) Nannochloropsis + aeration; and 4) Nannochloropsis alone. Results of the experiment indicated increses of dissolved inorganic carbon (DIC) as high as 2.56 mM/l in treatment 1 and 2.70 mM/l in treatment 2, whereas treatments 3 and 4 showed lower levels of 1.30 and 1.77 mM/l, respectively, during 6 days of culture. Furthermore, the total bicarbonate and carbonate were quantified as 93, 86, 78, and 85% of DIC in treatments 1, 2, 3, and 4, respectively. It can be concluded that a portion of the carbon which was supplied to the rotifer is recycled in the ecosystem culture.View full abstractDownload PDF (472K) -
Noboru MURASE, Masaharu OHGAI1996 Volume 44 Issue 1 Pages 59-65
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSMonthly changes in growth and maturation of Ecklonia kurome Okamura at a depth of 10 m off Nagashima in Seto Inland Sea, Yamaguchi Prefecture, were studied between September 1992 and September 1993. Maximum and minimum standing crop of the E. kurome community were recorded in August and December, respectively. Growth of adult plants as measured by wet weight increased from February through August and decreased from September through December. Maximum plant and central lamina lengths were observed in May. Longest primary pinna reached a maximum in June. Their lengths were minimum in December. Young plant growths were rapid from December through April. Soni formation was observed from September through December in the majority of plants with one growth ring or more. The dry weight per unit area of the primary pinna and the central lamina was highest in October.View full abstractDownload PDF (784K) -
Yukio UETA, Itaru KITAKADO1996 Volume 44 Issue 1 Pages 67-72
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSSelection of the form of spawning bed by oval squid, Sepioteuthis lessoniana, was studied by use of three different types of man-made spawning beds, e. g. fiberglass reinforced plastics (FRP) type, steel type and mid-water cage type, settled in the coastal waters of Tokushima Prefecture in 1991. Underwater observations of egg capsules were carried out by SCUBA diving during a period from May 1991 to July 1994. The number of egg capsules laid on the man-made spawning bed was ranked by the bed type as, FRP type > mid-water cage type > steel type. Moreover, the number of egg capsules laid on the man-made FRP spawning bed of the narrow space type, was much more than that on the wide type in the same material. The results obtained suggest that spawners prefer relatively narrow spaces for egg-laying.View full abstractDownload PDF (2260K) -
Maher SAMET1996 Volume 44 Issue 1 Pages 73-77
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe fine structure of the gill filaments of the Kuruma prawn, Penaeus japonicus, exposed to air were studied with transmission electron microcopy, and were compared to normal gill filaments. After 12h of 14°C air exposure, electron microscopic examinations of the gill filaments did not show any changes except in the configuration of the mitochondria. Contrasting with normal mitochondria, which show well developed cristae and an electron dense matrix, mitochondria in the air exposed prawns had collapsed and rearranged cristae. The normal mitochondria were called energized and the modified, non energized. During aerial exposure, oxygen supply to the metabolically active mitochondria decreased in the collapsed gills, electron transfer and ATP formation could not be harnessed efficiently, thus resulting in the modified mitochondria.View full abstractDownload PDF (3739K) -
Tatsuya UNUMA, Takeshi YAMAMOTO, Toshio AKIYAMA1996 Volume 44 Issue 1 Pages 79-83
Published: March 20, 1996
Released on J-STAGE: December 10, 2010
JOURNAL FREE ACCESSThree purified diets each containing testosterone, estrone, or estradiol at the level of 4.55×10-6 g steroid/g wet diet and an ethanol-treated diet as a control were fed to juvenile sea urchin, Pseudocentrotus depressus for 29 days to examine their influence on growth and food utilization. The sea urchins treated with estrone showed significantly higher body weight than the control group (p < 0.05) . Food intake and feed efficiency in the estrone-treated group were the highest among the four groups. The growth of the sea urchins treated with testosterone was slightly higher but not significantly different from that of the control group. Estradiol had no effect on growth and food utilization of juvenile sea urchin.View full abstractDownload PDF (495K) -
Yasuhito SUZUKI, Akihiro TAKEMURA1996 Volume 44 Issue 1 Pages 85-90
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSSingle or combined hormone treatments were made in the tiger puffer, Takifugu rubripes, in order to compare their effects on induction of oocyte maturation and ovulation. Fifteen mature females (2.5 to 7.8 kg), which were caught with fixed nets around the coast of Fukui Prefecture between April 26 and May 10, 1993, were divided into four experimental groups: human chorionic gonadotropin (HCG) group (200 IU/kg HCG at day 0 and 1000 IU/kg at day 3), HCG+chum salmon pituitary extract (HCG+SP) group (500 IU/kg HCG and 10 mg/kg SP at day 0), LHRHa (LHRH) group (0.7 to 1.0 mg/kg LHRH at day 0), and control (1 ml/kg saline) . Oocyte maturation and ovulation were observed in all the surviving fish of the HCG and HCG+SP groups and part of the LHRH group. No ovulatory effect was observed in the control group. These results suggest that HCG and SP were both effective for induction of ovulation of this fish. Number and diameter of eggs from the successfully ovulated fish ranged from 279, 000 to 792, 000 and from 1.21 to 1.30 mm, respectively. Large differences in hatching rate (0 to 83 %) were recognized among batches.View full abstractDownload PDF (1896K) -
Akira MIZUTA, Kazuo TABATA, Hirokazu KANAO1996 Volume 44 Issue 1 Pages 91-98
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSIn order to investigate the conditions for acceleration of testicular maturation of sex reversed gynogenetic females (phenotypically males) Hirame, Paralichthys olivaceus, due to long photoperiod and low water temperature treatments, these two groups were reared under the following different conditions. One group was reared under twice long photoperiod and low water temperature treatments with an 8 month short photoperiod during these treatments (group A) . The other group was reared under twice long photoperiod and low water temperature treatments with a 6 month short photoperiod during these treatments (group B) . The control group was reared under both natural temperature and photoperiod. Their testicular maturation was assessed from gonadsomatic index (GSI) and histological section.
Although GSI increased due to long photoperiod and low water temperature treatments, the testicular maturation was observed only in group A after a second treatment from histological investigation. Further, it was observed that these cysts had been filled with spermatogonia before the second treatment. From these results, it was suggested that at least an 8 month short photoperiod before the next treatment had to be taken for the acceleration of testicular maturation of sex reversed gynogenetic females (phenotypically males) Hirame due to long photoperiod and low water temperature treatments.View full abstractDownload PDF (11310K) -
Hironobu KOMAKI1996 Volume 44 Issue 1 Pages 99-104
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSGrowth and morphological development of red sea bream, Pagrus major larvae at 18, 21, 24°C were compared under laboratory conditions. Growth rate increased and the size of metamorphosis to the juvenile stage decreased with increasing rearing temperature. External body proportions of fish reared at 18°C resembled those of wild fish. Preanal length, head length, eye diameter and body depth of red sea bream reared at higher temperatures were proportionally larger than those measured 18°C. Other characteristics were relatively unaffected by water temperature. These results suggested that rearing temperature had marked effects on morphological development during larval growth.View full abstractDownload PDF (749K) -
Atsushi HAGIWARA, Yoshioki OOZEKI, Cheng-Sheng LEE1996 Volume 44 Issue 1 Pages 105-112
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe effects of food density on survival, growth and yield were examined for milkfish, Chanos chanos larvae up to 15 days after hatching. Four food densities from 0.1 to 20 rotifers/ml and two stocking densities (15 and 30/l) were tested in two trials. Survival and growth rates did not differ significantly between the two stocking densities. The highest larval survival and growth were obtained at the highest food level. Individual dry weight and survival rate were significantly and positively related to the rotifer density. From the analyses of total amount of food input (rotifers plus phytoplankton) and net growth (harvest minus stocked) in each 30-liter tank, feeding of more than 3.24 mg dry weight per liter was necessary to achieve positive net growth.View full abstractDownload PDF (691K) -
1996 Volume 44 Issue 1 Pages 113
Published: March 20, 1996
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSDownload PDF (22K)
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