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Volume 70 (2004)
- Issue 6 Pages 853-
- Issue 5 Pages 667-
- Issue 4 Pages 496-
- Issue 3 Pages 276-
- Issue 2 Pages 123-
- Issue 1 Pages 1-
Volume 70, Issue 2
Displaying 1-12 of 12 articles from this issue
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Originals
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HARUO YAMAGUCHI, TOSHITAKA NISHIJIMA, HIROKAZU NISHITANI, KIMIO FUKAMI ...2004 Volume 70 Issue 2 Pages 123-130
Published: 2004
Released on J-STAGE: June 03, 2005
JOURNAL FREE ACCESSIn eutrophic coastal environments in Japan, red tides have caused mass mortality of cultured and wild fish. It is known that the concentration of organic phosphorus is usually higher than that of inorganic phosphorus in such seawaters, and that many phytoplankton produce alkaline phosphatase (AP). To elucidate the contribution of organic phosphorus to the growth of red tide phytoplankton, organic phosphorus utilization and AP production of Karenia mikimotoi, Skeletonema costatum and Heterosigma akashiwo were examined. K. mikimotoi and S. costatum used organic phosphorus compounds (phosphomonoesters, ADP, and ATP) as a sole phosphorus source. These phytoplankton produced AP under orthophosphate concentration of less than 0.2 and 0.25 μM, respectively, and their AP activities were 115 and 0.273 fmol/cell/min, respectively. It was shown that these phytoplankton have sufficient potential AP activity necessary for the uptake of phosphorus to maintain saturated growth. On the other hand, H. akashiwo used ADP and ATP, but not phosphomonoesters, as phosphorus sources; AP production was not found. It is suggested that organic phosphorus contributes to the outbreaks of red tide in eutrophic coastal seawaters.View full abstractDownload PDF (440K) -
—Studies on the fishery management of northern shrimp Pandalus eous in the waters off Noto Peninsula, the Sea of Japan-IV—TSUTOMU SADAKATA2004 Volume 70 Issue 2 Pages 131-137
Published: 2004
Released on J-STAGE: June 03, 2005
JOURNAL FREE ACCESSThe age of sex change from male to female is estimated by two methods: One is a theoretical calculation based on the results obtained so far, or a practical observation of samples caught by a research vessel. The obtained results are as follows. The optimum age of sex change was calculated to be around 5 years old. The actual age of sex change in the waters off Noto Peninsula were 4, 5, and 6 years old. According to the year class, the first age of sex change varied annually with 4 or 5 years old. Namely, in copulation and spawning areas, the size of sex change tended to be small as the mean carapace length of the breeding population was small. The breeding population consisting of small individuals was most conspicuous when the number of females was fewer than that of males due to the sex change from male to female. So in this species, the size of sex change may vary owing to the population structure influenced by fishing pressure or recruitment of year class strength. At that time the small size of sex change is supposed to make the age of sex change lower.View full abstractDownload PDF (344K) -
MASAHIKO MIZUSAWA, ICHIRO AOKI, RYUJI YUKAMI, KEN-ICHI UTAGAWA, ISAMU ...2004 Volume 70 Issue 2 Pages 138-144
Published: 2004
Released on J-STAGE: June 03, 2005
JOURNAL FREE ACCESSOtolith microstructure was used to determine extrusion date, planktonic larval duration and settlement size of the juvenile black rockfish Sebastes inermis collected at two sites, Sajima and Kaneda Bay located along the coast of Miura Peninsula, central Japan. Early life histories of juveniles from the two locations were different. Juveniles from Sajima and Kaneda Bay were mainly extruded in February and in January, respectively. The duration of the planktonic period for Sajima (28-68 d) was significantly shorter than for Kaneda Bay (51-109 d). The back-calculated settlement size for Sajima (9.1-19.5 mm) was significantly smaller than for Kaneda Bay (12.0-26.1 mm). Sajima juveniles exhibited larval growth rates higher both during the planktonic period and after settlement than did Kaneda Bay juveniles. The growth rate during the planktonic period had an inverse correlation with planktonic larval duration within and between locations, indicating that individuals with faster growth had shorter planktonic durations than those with slower growth. These results suggested that respective groups might be distributed in the two study sites.View full abstractDownload PDF (383K) -
TATSUNARI MORI, SETSUO SAITO, CHIHARU KISHIOKA, KATSUTOSHI ARAI2004 Volume 70 Issue 2 Pages 145-151
Published: 2004
Released on J-STAGE: June 03, 2005
JOURNAL FREE ACCESSThe optimum conditions for inducing triploidy and gynogenesis by cold and pressure shock in barfin flounder Verasper moseri were examined. The sperm of barfin flounder was genetically inactivated by the dose of 10 mJ/cm2 UV irradiation. Triploids were induced by applying cold shock treatment with −1.5°C at 9 min after fertilization for 90 min duration. In this condition, hatching rate relative to the control was 29.2% and triploidy rate was 90.9%. Meiotic gynogenetic diploids were obtained by fertilizing eggs with UV-irradiated sperm and subsequent cold shock (−1.5°C) at 3-9 min after fertilization for 60-90 min duration and pressure shock (650 kg/cm2) at 7 min after fertilization for 6 min duration. Mitotic gynogenetic diploids were obtained by pressure shock (650 kg/cm2, 6 min) and applied at 150-240 min after fertilization.View full abstractDownload PDF (541K) -
TETSUO YAMADA, SHUNJI KAJI, MITSUGI WATANABE, EMIKO HASEGAWA, TATSUHIR ...2004 Volume 70 Issue 2 Pages 152-158
Published: 2004
Released on J-STAGE: June 03, 2005
JOURNAL FREE ACCESSAfter their release into natural waters at a small inlet in the Seto Inland Sea, two groups of juvenile red sea bream, Pagrus major, reared under either low- or high-intensity light were studied to clarify changes in behavior and population size. Released fish showed two behaviors: aggregation and solitary. The low-intensity light group showed predominance over the high-intensity light group both in the number of solitary individuals and the spatial distribution area in the small inlet. Differences in these characters between the two rearing groups caused differences in the number of individuals able to win territories in the process of behavioral shift from aggregation to solitary type during 4-5 days after release.View full abstractDownload PDF (431K) -
CHIZUKO NAGAOKA, YOSHIKAZU YAMAMOTO, SAYAKA EGUCHI, NOBUYUKI MIYAZAKI2004 Volume 70 Issue 2 Pages 159-167
Published: 2004
Released on J-STAGE: June 03, 2005
JOURNAL FREE ACCESSThe concentrations of heavy metals (Hg, Cd, Cu, Zn, Pb, Ni, Mn, Cr, Fe) were determined in surface sediment samples collected from Osaka Bay and Otsuchi Bay, Japan in 2000. Mean concentrations (μg/g dry wt) of heavy metals in sediments from Osaka Bay were as follows: Hg 0.34; Cd 1.23; Cu 44.9; Zn 242; Pb 57.8; Ni 37.8; Mn 888; Cr 49. The concentrations of heavy metals were higher in sediments from the northeastern parts of Osaka Bay. This is probably due to industrial and domestic wastewater delivered by rivers through large cities. Highly significant correlation coefficients were observed among the concentrations of heavy metals except for Mn. Mean levels of heavy metals in sediments of Osaka Bay were several times higher than those of Otsuchi Bay which is a non-industrialized area.
The distribution patterns of heavy metals, ignition loss and chemical oxygen demand were fairly similar, and inversely correlated with those of sediment grain-size in Osaka Bay. From these results, it is considered that the sediment grain-size and organic substance contents are probably the crucial parameters that control the concentration of heavy metals except for Mn.View full abstractDownload PDF (684K) -
NAOYUKI MISAKA, SHINYA MIZUNO, YASUYUKI MIYAKOSHI, KATSUMI TAKEUCHI, T ...2004 Volume 70 Issue 2 Pages 168-174
Published: 2004
Released on J-STAGE: June 03, 2005
JOURNAL FREE ACCESSWe evaluated whether triglyceride and glycogen levels in the liver of masu salmon Oncorhynchus masou fry were suitable indices of starvation. Triglyceride levels gradually declined during the spring for each of four groups in a hatchery (wild-origin fed fry, wild-origin unfed, hatchery-origin fed, and hatchery-origin unfed), as well as for hatchery-origin fry from a river, while glycogen levels did not. Triglyceride levels also declined gradually during winter for wild-origin fish brought back to the hatchery, regardless of whether they were fed. Glycogen levels declined rapidly for those fish that were not fed. Regardless of the season, unfed fish began to die when triglyceride levels reached a level significantly lower than that found among fed fry or fry caught in the river. We conclude that triglyceride content is a useful index of hard starvation for underyearling masu salmon. In contrast, seasonal patterns must be considered before glycogen levels can be used as an index of starvation.View full abstractDownload PDF (371K) -
SHINGO KIMURA, HIDEAKI NAKATA, DANIEL MARGULIES, JENNY M. SUTER, SHARO ...2004 Volume 70 Issue 2 Pages 175-178
Published: 2004
Released on J-STAGE: June 03, 2005
JOURNAL FREE ACCESSTank experiments were conducted to study the effect of oceanic turbulence on the survival of first feeding larvae of yellowfin tuna. Several levels of turbulence intensity were provided by changing the amount of air bubbles released from air-stones in the tanks containing yellowfin tuna larvae. The results showed that there is an optimal turbulence intensity which enhances larval survival. This turbulence intensity was equivalent to approximately 1−2×10-8 m-2s-3 as an energy dissipation rate, suggesting that the surface mixed layer of equatorial oceans used for spawning by the yellowfin tuna is a suitable environment for the survivals of larrae.View full abstractDownload PDF (643K) -
TEI KISHINO, AKIHIKO SHINOMIYA2004 Volume 70 Issue 2 Pages 179-186
Published: 2004
Released on J-STAGE: June 03, 2005
JOURNAL FREE ACCESSThe Ryukyu-ayu Plecoglossus altivelis ryukyuensis inhabits very limited areas of the Ryukyu Islands in southern Japan. A field study was carried out to clarify the body sizes, day ages, and number of upstream migrating individuals of Ryukyu-ayu at the Kawauchi and Yakugachi Rivers flowing into Sumiyo Bay in Amami-oshima Island in 1994. The upstream migration from the sea lasted for four months from late January to late May at both rivers. The fish which migrated to the river ran into the upper reaches and kept growing there. The average migrating speed in the lower and middle reaches was slow, 220 (133-300) m/day. The smaller size of fish (mean body length: 34.0 mm) and the number of riffles to the lower and middle reaches influenced their migrating speed. The speed in the upper reaches was slower, 125-128 m/day, while fish grew larger (mean body length: 73.3 mm). The condition factor and growth rate of the fish in the upper reaches were remarkably higher than those in the lower and middle reaches. These results show that the fish in the upper reaches might have migrated upward by repeatedly moving and staying.View full abstractDownload PDF (729K) -
YUJI OMURA, EMIKO OKAZAKI, YUMIKO YAMASHITA, MASAKATU YAMAZAWA, SHUGO ...2004 Volume 70 Issue 2 Pages 187-193
Published: 2004
Released on J-STAGE: June 03, 2005
JOURNAL FREE ACCESSThe color of dried, seasoned and shredded squid products (“sakiika” in Japanese) often becomes brown, probably due to the Maillard reaction, which has been one of the most serious problems in “sakiika” product industries. In this study, we determined the change in the contents of neutral reducing-sugars such as ribose and glucose of common squid (Tedarodes pacificus) in relation to the browning of the products during preservation. Sample squid frozen on board after fishing was thawed and mantle muscle was allowed to stand for 6 h at 5, 10 and 15°C. Samples with different grades thus prepared were boiled at 80°C for 20 min, freeze-dried, and ground into powder, which was named “dried-squid product browning model” and preserved for 30 days at 35°C. During thawing at 5°C and storage at 5, 10 and 15°C, ribose was accumulated in the mantle muscle of the squid, probably resulting from post-mortem degradation of ATP and related compounds. During preservation at 35°C, the browning rapidly occured with the model samples prepared from any grade. It was noted that the content of ribose before storage at 35°C was higher in the model samples prepared from less fresh mantle muscle.
The b* value of color difference measured as a parameter of the browning rapidly increased during storage at 35°C, showing a high coefficient in the linear regression against the decrease of ribose (R2 = 0.76-0.83). On the other hand, the decrease of glucose in the model samples showed no apparent relation to the b* value. These results suggest that ribose plays a major role in the browning of “sakiika”.View full abstractDownload PDF (515K) -
SHOTA TANIMOTO, TAMIHARU YAMASHITA, NOBUO SEKI2004 Volume 70 Issue 2 Pages 194-199
Published: 2004
Released on J-STAGE: June 03, 2005
JOURNAL FREE ACCESSPig plasma was freeze dried and fractionated into 5 fractions, namely I, II+III, IV−1, IV−4, and V, according to the method of Cohn. Walleye pollack surimi paste was prepared by mixing surimi with 2.7% NaCl and 25% water containing various amounts of pig plasma powder or plasma fractions and then preheated at 60°C for 0-120 min to induce modori prior to heating at 90°C for 30 min. During preheating, the surimi gel strength and deformation greatly decreased. The addition of pig plasma more than 0.2% completely inhibited not only modori but also the breakdown of myosin. To investigate active components in pig plasma, each fraction was added to the surimi paste and heated at 60°C. The fractions II+III and IV−4 showed higher inhibitory effects on modori and myosin degradation. The mixture of fractions II+III and IV−4 almost completely inhibited both reactions. These results suggest that the modori inhibitory activity of pig plasma is mainly ascribed to the inhibition of myosin degradation by more than two components in the fractions II+III and IV−4 containing proteinase inhibitors.View full abstractDownload PDF (742K)
Short paper
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HIRONORI FUJISHIMA, TOSHIKO GAMANO, YUKAKO TAOKA, TOMOO SAWABE, YUTAKA ...Article type: Others
Subject area: Others
2004 Volume 70 Issue 2 Pages 200-202
Published: 2004
Released on J-STAGE: June 03, 2005
JOURNAL FREE ACCESS
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