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Yoshihiro Suzuki, Toshiroh Maruyama, Daisuke Sato, Takeshi Kanda, Tamo ...
2000 Volume 66 Issue 1 Pages
1-9
Published: January 15, 2000
Released on J-STAGE: February 01, 2008
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In this study, water quality and mass balances in the closed recirculating culture of Japanese flounder were examined. The closed system consisted of rearing thank, foam-separation and nitrification units, pH and temperature controlling units, and a circulation pump. Fish were fed commercial pellet diet for 90 days. Average values of oxygen saturation and turbidity in the rearing water through the culture were 96% and 3.1 TU, respectively. Ammonia was mostly kept at less than 1mg-N/l, and nitrate increased linearly according to the amount of diet supplied. It is estimated that 33% of dietary carbon (C) was accumulated in the fish, as well as 52% of nitrogen (N), and 26% of phosphorus (P). The carbon released as CO
2 was 63%. Nitrate in the rearing water corresponded to 28% of N-input, and 66% of P was settled in the nitrification unit as precipitate.
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Ichiro Aoki, Teisuke Miura, Nobuyuki Imai, Teruhisa Komatsu
2000 Volume 66 Issue 1 Pages
10-17
Published: January 15, 2000
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A frame-type midwater trawl with a mouth area of 16m
2 was developed to capture large larvae and juveniles of pelagic fish. Sampling was conducted in the waters around Izu Islands, central Japan, and off northeastern Japan in summer 1996 and 1997. Large larvae and juveniles (TL>30mm) which avoid small mouth nets, were captured. Though several species of pelagic fish were collected, Japanese anchovy Engraulis japonicus occurred predominantly. In some tows where thousands of anchovy larvae and juveniles were collected, the abundance of larger ones (TL>30mm) was estimated as about 70 inds./1, 000m
3. Total length of the largest fish collected were 80mm for anchovy, 37mm for Japanese sardine Sardinops melanostictus, 82mm for chub mackerel Scomber japonicus, and 48mm jack mackerel Trachurus japonicus.
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Tsutomu Sadakata
2000 Volume 66 Issue 1 Pages
18-24
Published: January 15, 2000
Released on J-STAGE: February 01, 2008
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From the analysis of monthly samples caught at different depths, the following results were obtained. The Northern Shrimp spawns eggs in March and April, and hatches larvae in January and February after a ovigerous period of about 10 months. The species spawns every other year. Similar characteristics were found for the ovigerous period and spawning interval among populations living in cold waters. The reproduction strategy of this species is to spawn many eggs per clutch in spite of its slow growth rate and late spawning age.
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Takashi Tojima, Nobuaki Arai
2000 Volume 66 Issue 1 Pages
25-32
Published: January 15, 2000
Released on J-STAGE: February 01, 2008
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Elemental analyses, using wave-length dispersive X-ray spectrometers, on the otolith of 1-year-old red sea bream, Pagrus major, from five areas in the Tsushima Warm Current showed the two fluctuation patterns of strontium L
α X-ray counts. The strontium X-ray counts in the otolith sections from the area off Nagasaki Prefecture were approximately constant while some slight fluctuations on the edge were found in a few otoliths. However, the counts in the otoliths from the area off Akita Prefecture distinctively increased with otolith growth and decreased after peaks were shown. Coefficients of variation of strontium X-ray counts of individuals were 5.84∿8.53% for fish from the area off Nagasaki Prefecture and 6.44∿13.40% for fish from the area off Akita Prefecture.
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Jun Nishikawa, Takeshi Sonoda, Izumi Sakurai, Masafumi Seto, Shigeru N ...
2000 Volume 66 Issue 1 Pages
33-43
Published: January 15, 2000
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Diets of flatfishes and other demersal fishes and relations between their assemblages and macrobenthos were investigated by examining stomach contents of 32 species of demersal fishes, and seasonal abundance of macrobenthos collected off the coast of Tomakomai. Flatfishes Hippoglossoides pinetorum, Pleuronectes herzensteini and Kareius bicoloratus fed exclusively on polychaete Onuphis holobranchiata through the year. Diet of other main demersal fishes Spirinchus lanceolatus, Eleginus grcilis, Myoxocephalus jaok, Podothecus sachi, Arctoscopus japonicus, varied in each season. They fed chiefly on juvenile fishes in June and August, Onuphis holobranchiata in August and September, Mysidacea and Macrura in December. There was considerable influence of seasonal abundance and size utilization of prey species in food selection of predators. Especially Onuphis holobranchiata recruited in summer and became an important food resource for many fishes.
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Yasuhiko Tago
2000 Volume 66 Issue 1 Pages
44-49
Published: January 15, 2000
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The upstream migration and the summer stay of adult masu salmon Oncorhynchus masou were investigated in the Jinzu River and the Shou River of the Hokuriku region from 1991 to 1995. The period of upstream migration estimated from the monthly fluctuation of the catch data of masu salmon in the Jinzu River was from February to June, and the peak was in May. The mean fork length of the migrants was 58.5±4.9cm and the mean body weight was 2.8±0.8kg, and the female occupied 74.7% of the total. In the fishing surveys using the drift net in the Shou River, the number of adult masu salmon caught at the pools of the middle reaches occupied 96.4% of total catch. Most of fish (80.2%) caught from the the Jinzu River had empty stomachs. These findings indicate that adult masu salmon migrates to a river and stays in the pools of the middle reaches during summer season, feeding rarely. For effective increase of masu salmon resources, the preservation and/or the reconstruction of larger and deeper pools in a river are very important.
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Takafumi Ito, Akio Kera, Hisashi Murata, Terutoyo Yoshida, Tadashi Sak ...
2000 Volume 66 Issue 1 Pages
50-54
Published: January 15, 2000
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To elucidate whether yellowtail Seriola quinqueradiata experimentally infected with the jaundice-causing bacteria suffer from severe oxidative stress, hemoglobin level in the blood, malondialdehyde (MDA), α-tocopherol (α-Toc) levels in the liver and plasma, and phosphatidylcholine hydroperoxide (PCOOH) level in the liver of the fish were analyzed after an intraperitoneal injection with the causative agent of bacterial hemolytic jaundice. The bacterial injection brought hemolysis and jaundice in the fish. The liver PCOOH and MDA levels and the plasma MDA level increased and the plasma α-Toc level decreased in the infected fish. These results suggest that yellowtail experimentally affected by the jaundice suffer from severe oxidative stress. We have recognized that severe oxidative stress led to induction of heme oxygenase catalyzing bilirubin synthesis in the liver of yellowtail. Therefore, we consider that the jaundice of yellowtail caused by the causative bacteria is due to the stimulation of bilirubin synthesis induced by severe oxidative stress.
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Masaharu Tsuji, Kazuo Ikeda, Hiromi Ohta
2000 Volume 66 Issue 1 Pages
55-61
Published: January 15, 2000
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When milt from the ayu Plecoglossus altivelis altivelis (Suborder Salmonoidei) was diluted with seminal plasma or artificial seminal plasma (ASP) consisting of 115.2mM NaCl+12.8mM KCl+1.6mM CaCl
2+0.6mM MgCl
2+20mM NaHCO
3 buffered with 20mM TAPS-NaOH at pH8.0, few spermatozoa initiated motility. The percentage of motility increased up to 35.9% with decreasing concentrations of potassium ions in ASP. Spermatozoa exhibited a high percentage of motility when they were diluted with isotonic nonelectrolyte mannitol solution. Adding KCl or NaCl to the mannitol solution (total osmolality of each solution was adjusted at 300mOsm/kg by decreasing the concentration of mannitol) decreased the motility in a dose-dependent manner (0-5mM in KCl and 0-105mM in NaCl, respectively). Calcium ions could overcome the inhibition of motility by potassium and sodium ions. Increases in calcium concentration in ASP increased the percentage motility up to 94.5% at 20mM. Acidification of ASP at pH 6.0 also induced a high percentage of motility (76.3%). These results indicate that ayu spermatozoa motility in the seminal plasma is suppressed with various ionic compositions (high concentrations of potassium and sodium ions, and low concentrations of calcium and hydrogen ions).
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Ryozo Sato, Nobuhiro Suzuki, Naoaki Kamiya, Akira Tsujigado, Kazuhiro ...
2000 Volume 66 Issue 1 Pages
62-69
Published: January 15, 2000
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We obtained 69, 168 naturally spawned eggs of the ocellate puffer from 11 sampling stations in the spawning ground off Anori, Mie Prefecture, using a skidnet on the 15th and 23rd April, 1993. Naturally spawned eggs were not distributed uniformly. The number of days reqired until hatching varied among the stations and was estimated to range from 4 to 10 days and a considerable number of parental fish were estimated to be involved in spawning. Fry from 4 stations were raised to an average standard length of 8.5∿11.9cm and then PGM isozyme in muscle and IDH isozyme in liver of fry were analyzed by horizontal starch-gel electrophoresis. The PGM-c gene frequencies of St. 4 and St. 10 in the eastern region were 0.806 and 0.816, respectively, whereas in the western region, St. 6 and St. 11 were 0.621 and 0.608, respectively. The IDH-N gene frequency of St. 4 was 0.707, in contrast that of St. 11 was 0.539. These results imply that two spawning groups, one in each of the eastern and western areas of this spawning ground exsisted. However, it is necessary to examine whether these spawning groups correspond to stocks. Moreover the number of parent fish spawned in the spawning ground were estimated to be at least 61 to 233 individuals from the frequencies of the rare genotypes and genes. These estimations obtained from isozyme analysis are supported by data on the distribution and hatching of naturally spawned eggs.
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Akiyoshi Kamatani, Osamu Oku, Hisae Tsuji, Masaru Maeda, Yoshiaki Yama ...
2000 Volume 66 Issue 1 Pages
70-79
Published: January 15, 2000
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The distribution and seasonal change of phosphate, silicic acid and nitrate of Sagami Bay were studied from 1993 to 1994. The concentrations and the ratios of these three components in the waters located below the sub-surface layer were shown to be quite similar as those observed 15 years ago. This finding could be ascribed to the fact that the nutrients caused by the increasing coastal eutrophication to date are quickly washed out into the open ocean by the presence of a fairly strong current : the residence time of the waters in this bay being short. The nutrients in the euphotic zone were often depressed to less than the limiting level for phytoplankton growth when the seasonal thermocline set over. The potential importance of silicon for diatom growth was essentially sustained by the upwelling of silicic acid enriched sub-surface waters and/or by the river waters. It was thus concluded that the nutrient environments in Sagami Bay are still favorable for the maintenance of diatom ecosystems.
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Yukichika Okada, Tokio Wada
2000 Volume 66 Issue 1 Pages
80-87
Published: January 15, 2000
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The relationships between the number of parents, the egg production in the eastern area from the Shionomisaki of the Pacific water off Japan from 1978 to 1994, and the number of children, the cumulative egg production of progeny from 1978 to 1994 year-classes, of the Pacific stock of Japanese anchovy were investigated. We obtained the cumulative egg production of progeny from the egg production of the Pacific stock of Japanese anchovy divided by the ratio of relative annual fecundity estimated from past studies and the annual adult catch every year from 1978 to 1996. Reproduction relationships of 1978-1988 year-classes differed from 1990-1994 year-classes. The reproductive relationship of the former was constant when the stock abundance was low and that of the latter fluctuated when it was high.
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Hiromi Ohta, Tatsuya Unuma, Hiroyuki Nagoya
2000 Volume 66 Issue 1 Pages
88-96
Published: January 15, 2000
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Diluents for cool storage of milt and for artificial fertilization which induce a high percentage of motility of stored spermatozoa were examined. Milt was stored in artificial seminal plasma (ASP; NaCl+KCl=140mM, CaCl
2 1.6mM, MgCl
2 1.0mM and NaHCO
3 10mM buffered with 20mM TAPS-NaOH at pH 8.0) of various KCl concentrations (0 to 50mM) at 4°C for 10 days. The sperm motility was examined after dilution with DW (buffered with 10mM TAPS at pH 8.0) or 120mM NaHCO
3. Increasing the potassium concentration of ASP to 30mM increased the percent motility. The spermatozoa stored for two days in Ca-free ASP showed remarkably decreased motility. The motility of stored spermatozoa is also influenced by the pH of ASP. A 120mM NaHCO
3 solution induced a higher percentage and longer duration of motility of stored spermatozoa than DW. A 120mM NaCl solution and an artificial coelomic fluid also induced a higher percent motility; no significant differences in motility were detected among these three solutions. Adding 5mM IBMX (3-isobutyl-1-methylxanthine) to 120mM NaHCO
3 or 120mM NaCl failed to increase the percent motility. Changing NaHCO
3 concentration from 60 to 180mM induced no significant difference of percent motility either 5 to 7 sec or 15 to 17 sec after the dilution.
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Kengo Fukuda, Fuxiang Hu, Tadashi Tokai, Ko Matuda
2000 Volume 66 Issue 1 Pages
97-103
Published: January 15, 2000
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This paper describes the effect of aspect ratio on the lift and drag characteristics of the cambered plates in free stream. Nine types of model plates (camber ratio of 15%) with different aspect ratios (0.5∿6.0) were tested in a circulating water tank. The lift coefficient took the maximum value of 1.783 for the model plate with the aspect ratio of 1.0, while this decreased at the aspect ratios ranging from 1.0 to 3.0, but increased again gradually at aspect ratios over 3.0. However, the lift-to-drag ratio increased with increasing aspect ratio. These findings were consistent with the data of the Clark Y type airfoil by Zimmerman. Because maximum lift coefficient is more important than lift-to-drag ratio for the otter boards, a study for practical utility may be needed for the cambered otter boards with small aspect ratios of approximately 1.0.
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Koichi Kataura, Satomi Koseki, Hiroko Ogawa, Fumito Yamazaki, Yoshiaki ...
2000 Volume 66 Issue 1 Pages
104-109
Published: January 15, 2000
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It has previously been reported that under fluorescent light, chlorophyll α dissolved in ethanol decomposed with a concomitant formation of several new components, as measured by high performance liquid chromatography, developed green color for a long term. In the present study, we tried to find another material appropriate for the extraction of chlorophyll-related compounds, preferably with green color. Thus the comparison was made on yield, color, and odor of ethanol-extracted chlorophyll-related compounds among unsalted and salted brown seaweeds and some vegetable sources. Consequently, ethanol-extracted chlorophyll-related compounds from the salted brown seaweed, Konbu Laminaria japonica were much better at conferring the greenish color together with a pleasant odor, when combined with seasoning extractive from the Konbu. In addition, the ethanol-extracted chlorophyll-related compounds from the salted Konbu, Laminaria japonica were found to contain several similar components which can be assumed to be allomerized products of the chlorophyll molecule.
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Kayoko Kasahara, Chieko Osawa
2000 Volume 66 Issue 1 Pages
110-117
Published: January 15, 2000
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Characteristic volatile components of roasted semi-dried horse mackerel were investigated by comparison with the following samples : (1) roasted semi-dried yellow sea bream and sardine, (2) three roasted fishes, (3) three boiled fishes, (4) three semi-dried fishes and (5) three raw fishes. The Maillard reaction and the lipid oxidation were then studied to elucidate the production mechanisms of the characteristic volatiles by roasting. 2-Methylpropanal, 2-methylbutanal and 3-methylbutanal were identified as the main characteristic components of three roasted semi-dried fishes by gas chromatography and gas chromatography-mass spectrometry, and the peak areas of these components were larger than those of the three roasted fishes. These components were found to be produced by the Maillard reaction during heating and to contribute to the roasting odor partially. On the other hand, propanal and 2-ethylfuran, which were identified in the roasted sun-dried horse mackerel and the semi-dried sardine, were thought to be produced by lipid oxidation. Moreover, 2-methylpropanal and 3-methylbutanal were increased by adding valine and leucine, and masked the rancid odor.
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Chitari Ono, Sadaaki Yoshimatsu, Satoshi Matsuoka, Yoichi Yoshida
2000 Volume 66 Issue 1 Pages
118-119
Published: January 15, 2000
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Takumi Fukuda, Hisashi Kurokura, Takayoshi Ueda
2000 Volume 66 Issue 1 Pages
120-121
Published: January 15, 2000
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Takafumi Ito, Akio Kera, Hisashi Murata, Terutoyo Yoshida, Tadashi Sak ...
2000 Volume 66 Issue 1 Pages
122-123
Published: January 15, 2000
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Toshiie Sakata
2000 Volume 66 Issue 1 Pages
125-126
Published: January 15, 2000
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Hiromichi Okuda
2000 Volume 66 Issue 1 Pages
127-128
Published: January 15, 2000
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Hideo Kato
2000 Volume 66 Issue 1 Pages
129-130
Published: January 15, 2000
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Shinya Fuke
2000 Volume 66 Issue 1 Pages
131-132
Published: January 15, 2000
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Toshiaki Ohshima
2000 Volume 66 Issue 1 Pages
133-134
Published: January 15, 2000
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Keiko Hatae
2000 Volume 66 Issue 1 Pages
135-136
Published: January 15, 2000
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Hiroaki Saito
2000 Volume 66 Issue 1 Pages
137-138
Published: January 15, 2000
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Akihide Takiguchi
2000 Volume 66 Issue 1 Pages
139-140
Published: January 15, 2000
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Toshiyasu Yamaguchi
2000 Volume 66 Issue 1 Pages
141-142
Published: January 15, 2000
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Emiko Okazaki
2000 Volume 66 Issue 1 Pages
143-144
Published: January 15, 2000
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Masahiko Kitagawa
2000 Volume 66 Issue 1 Pages
145-146
Published: January 15, 2000
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Yoshinobu Hiraoka
2000 Volume 66 Issue 1 Pages
147-148
Published: January 15, 2000
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Shuichi Kitada
2000 Volume 66 Issue 1 Pages
150-151
Published: January 15, 2000
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Masahide Kaeriyama
2000 Volume 66 Issue 1 Pages
152-153
Published: January 15, 2000
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Yasushi Harada
2000 Volume 66 Issue 1 Pages
154-155
Published: January 15, 2000
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Misao Arimoto
2000 Volume 66 Issue 1 Pages
156-157
Published: January 15, 2000
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Yoshiharu Matsumiya
2000 Volume 66 Issue 1 Pages
158-159
Published: January 15, 2000
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