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991.
Hikaru Watanabe Makoto Okazaki Tsutomu Tamura Kenji Konishi Denzo Inagake Takeharu Bando Hiroshi Kiwada Tomio Miyashita 《Fisheries Science》2012,78(3):557-567
This study represents the first quantitative analysis of the characteristics of the distribution areas and stomach contents
of common minke whale Balaenoptera acutorostrata, sei whale B. borealis, and Bryde’s whale B. edeni in relation to oceanographic and prey environments in mid summer in the western North Pacific. Common minke whales were distributed
within subarctic regions and the northernmost region of the transitional domain, coinciding with the main habitat of their
preferred prey, Pacific saury Cololabis saira. Sei whales were mainly found in the northernmost part of the transition zone and showed prey preference for Japanese anchovy
Engraulis japonica, which was significantly more abundant in the main distribution area of the whale than in its adjacent areas. “Hot spots”
of Bryde’s whales were found in several regions of the transition zone between the subarctic boundary and the Kuroshio front.
This whale species preferred Japanese anchovy as prey, for which the distribution density was significantly higher in the
main distribution area of the whale than in the adjacent areas. These results indicate that the summer distributions of Pacific
saury and Japanese anchovy greatly influence the distributions of these whale species, suggesting that the whales’ habitat
selection is closely related to their prey selection. 相似文献
992.
Climate change and interspecific interactions drive species alternations between anchovy and sardine in the western North Pacific: Detection of causality by convergent cross mapping
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Shin‐Ichiro Nakayama Akinori Takasuka Momoko Ichinokawa Hiroshi Okamura 《Fisheries Oceanography》2018,27(4):312-322
The abundance and recruitment of anchovy Engraulis spp. and sardine Sardinops spp. alternate in a synchronized way across the Pacific. Convergent cross mapping (CCM) indicated that climate change drives the alternation of the two species in the California Current System. However, climate indices patterns in the western North Pacific contrast with those in the eastern North Pacific, despite synchronous species alternations occurring. Therefore, it is of great interest to clarify whether climate change, or any other factors, affects the population dynamics of Japanese anchovy and Japanese sardine in the western North Pacific. Using CCM, we tested whether climate change and interspecific interactions affect the population dynamics of these two species. We found that climate change affected recruitment, and we clarified the spatiotemporal pattern of this effect. This result supports the existing hypotheses that population dynamics are regulated by climate change in the western North Pacific. The present study also detected interspecific interactions between sardine and anchovy, which might promote the alternation of the two species, and has not been reported in other regions. 相似文献
993.
Susumu Uji Tadahide Kurokawa Hiroshi Hashimoto Tohru Suzuki Koichi Okuzawa 《Aquaculture Research》2014,45(6):1096-1108
Muscles play important roles in feeding, respiration and swimming during not only adult stage but also larval stage in fish. However, there is no information of the muscle development in larval greater amberjack, Seriola dumerili (Risso). Here, we investigated muscle development in the greater amberjack, focusing primarily on the cranial muscles from 0 days post hatch (dph) to 12 dph using a modified whole‐mount immunohistochemical staining method. We found that the muscles required for feeding develop by 3 dph, when the larvae begin to feed. Subsequently, muscle composition in the dorsal branchial arches changes to the adult form between 5 and 8 dph. At 8 dph, all the muscles required for feeding and respiration appear, whereas the dorsal, pelvic and caudal fin muscles required for swimming develop later. This report provides fundamental information on larval greater amberjack muscle development, which will enable the detection of abnormal larval muscles and improve larval rearing techniques by modifying environmental conditions. 相似文献
994.
Hiroshi Ashida Toshiyuki Tanabe Keisuke Satoh Atsushi Fukui Sho Tanaka Nobuhiro Suzuki 《Fisheries Science》2010,76(5):785-793
The reproductive biology of male skipjack tuna Katsuwonus pelamis was examined from May 2005 to December 2007 in the tropical western and central Pacific Ocean. Testis maturity was classified
into five stages (i.e., immature, early maturation, mid maturation, late maturation, and regression) on the basis of morphological
changes in the germinal epithelium. The testis duct system (TS), which was characterized by lobules that lack spermatocysts,
store only sperm, and form an anastomosing network, was located under the main sperm duct. The TS was observed at all stages
of maturity except the immature stage, and first appeared in individuals with a fork length (FL) of 38–40 cm. The estimated
minimum size at first maturity was 35.5 cm FL and the size at 0.5 maturity was 40.7 cm in FL. It was difficult to clearly
differentiate the testis maturity stage based solely on the gonad index (GI) class because each GI class contained mature
fish. Monthly changes in testis height index and GI did not follow a seasonal cycle. Mature individuals dominated throughout
the year. These results imply that male skipjack tuna in this area showed evidence of spawning activity throughout the year
without a clear seasonal pattern. 相似文献
995.
Hiroyuki Matsunari Hiroshi Hashimoto Kentaro Oda Yoshitsugu Masuda Hitoshi Imaizumi Kazuhisa Teruya Hirofumi Furuita Takeshi Yamamoto Kazuhisa Hamada Keiichi Mushiake 《Aquaculture International》2012,20(5):981-992
The effect of algae with different DHA contents used for the enrichment of rotifers on the growth performance, survival, and swim bladder inflation of larval amberjack Seriola dumerili was investigated. Rotifers were enriched with freshwater Chlorella vulgaris containing three levels of DHA (rotifer containing DHA 0.04, 0.60, 1.32?g DHA 100?g?1 DM) and Nannochloropsis (0.04?g DHA 100?g?1 DM; 2.54?g EPA 100?g?1DM). The larvae were fed the enriched rotifers in triplicate from 3?days post-hatch for 7?days in static condition. The same algae used for rotifer enrichment were supplied to the larval tanks. Growth and survival rate of fish fed the rotifers enriched with Nannochloropsis were higher than those of fish fed the rotifers enriched with all three Chlorella treatments. Swim bladder inflation was lowest in fish fed the rotifers enriched with Nannochloropsis. The proportion of EPA was higher in fish fed the rotifers enriched with Nannochloropsis, while that of DHA increased proportionally with the DHA levels in the rotifers enriched with Chlorella. These results suggest that rotifers enriched with Nannochloropsis (EPA-rich rotifers) are effective to enhance growth and survival, but DHA instead of EPA is essential to improve the swim bladder inflation in amberjack larvae. 相似文献
996.
Yosuke Tanaka Hiroshi Minami Yuka Ishihi Kazunori Kumon Kentaro Higuchi Takeshi Eba Akefumi Nishi Hideki Nikaido Satoshi Shiozawa 《Aquaculture Research》2014,45(3):537-545
In mass culture of Pacific bluefin tuna Thunnus orientalis, a marked growth variation is observed after they start feeding at 6–7 mm in body length (BL) on yolk‐sac larvae of other species, and the growth variation in tuna larvae is a factor leading to the prevalence of cannibalism. To examine the relationship between prey utilization and growth variation, nitrogen stable isotope ratios (δ15N) of individual larvae were analysed. A prey switch experiment was conducted under two different feeding regimes: a group fed rotifers (rotifer fed group), and a group fed yolk‐sac larvae of spangled emperor, Lethrinus nebulosus (fish fed group) from 15 days after hatching (6.87 mm BL). The fish fed group showed significantly higher growth than the rotifer fed group. Changes in the δ15N of the fish fed group were expressed as an exponential model and showed different patterns from those of the rotifer fed group. The δ15N of fast‐growing tuna larvae collected in an actual mass culture tank after the feeding of yolk‐sac larvae was significantly higher than those of the slow‐growing larvae, indicating that slow glowing larvae depended largely on rotifers rather than the yolk‐sac larvae. 相似文献
997.
Teruya Maki Hiroshi Hasegawa Hiroyuki Kitami Kyoko Fumoto Yukihiro Munekage Kazumasa Ueda 《Fisheries Science》2006,72(4):811-820
ABSTRACT: Antibiotic residues in marine sediments of fish farms negatively influence microbial ecologic systems. The microbial degradation of antibiotic residues was experimentally examined in the marine sediments of Uranouchi Bay, to which one of five antibiotics was added. After incubation reducing physical factors, ampicillin, doxycycline, oxytetracycline, and thiamphenicol were significantly degraded, while josamycin maintained most of the initial amounts. The isolates resistant to ampicillin, josamycin, oxytetracycline, or thiamphenicol degraded each antibiotic in wide ranges of degrees, whereas the isolates degrading doxycycline were not obtained. Microbial degradation may contribute to the disappearance of ampicillin, doxycycline, oxytetracycline, and thiamphenicol in the fish farm. In contrast, the disappearance of josamycin would depend on physical factors, but the bacteria degrading josamycin at least exist in the marine sediments. Phylogenetic analysis using 16S rDNA sequences demonstrated that the antibiotic-resistant isolates formed several clusters in the Gram-positive bacterial group, the Flavobacterium–Cytophaga–Bacteroides group, and the proteobacteria subdivisions. The antibiotic-resistant bacterial population would be composed of various species including ubiquitous coastal bacterial groups. Several species of antibiotic resistant bacteria show antibiotic degradation activities, and appear to contribute to the disappearance of antibiotics in Uranouchi Bay. 相似文献
998.
Masaki FUJIMOTO Hiroshi KITAMURA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2022,84(4):507
The Cre-loxP system is widely used to investigate the cell-type specific roles of genes of interest. Cre-driver mice are required for cell-type specific knockout during the Cre-loxP reaction. To maintain Cre-driver mouse strains, Polymerase chain reaction (PCR)-oriented genotyping targeting the Cre gene cassette is usually conducted. In this study, we instead applied a colorimetric loop-mediated isothermal amplification (LAMP) method for Cre-genotyping. Among four sets of primers designed by the in silico program, one set effectively amplified the Cre cassette of three Cre-driver strains, but not of C57BL/6 mice. This LAMP-oriented method reduces assay time by less than half compared to the PCR-based method, and can be carried out using a conventional isothermal incubator. Applying this LAMP method may accelerate genotyping of Cre-driver mice. 相似文献
999.
1000.
Differences in rumen fermentation characteristics between low‐yield and high‐yield dairy cows in early lactation
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Ahmad Sofyan Makoto Mitsumori Hideyuki Ohmori Yutaka Uyeno Toshiya Hasunuma Kiyoshi Akiyama Hiroshi Yamamoto Hiroaki Yokokawa Tsuneko Yamaguchi Takumi Shinkai Makoto Hirako Shiro Kushibiki 《Animal Science Journal》2017,88(7):974-982
Relationship between rumen fermentation parameters, blood biochemical profiles and milk production traits in different yielding dairy cows during early lactation was investigated. Twelve dairy cows were divided into two groups based on their milk yield, that is low‐yield (LY) and high‐yield (HY) groups. Rumen fluid and blood were collected at 3 weeks prepartum and 4, 8 and 12 weeks postpartum. Results showed that proportions of acetate, propionate to total short chain fatty acids and acetate : propionate ratio were changed (P < 0.05) in both groups during the peripartum period, whereas butyrate and acetate : butyrate ratio were only altered in the HY group. Blood cholesterol, beta‐hydroxybutyric acid (BHBA) and glutamic oxaloacetic transaminase in the HY group were higher (P < 0.01) than those in the LY group. Principal component analysis revealed that milk yield and milk compositions were differently clustered between groups. These parameters showed similar direction with dry matter intake in the HY group and adverse direction in the LY group. Linear regression analysis indicated that butyrate was positively correlated with BHBA (P < 0.05) in the HY group. This study suggests that cows in the HY group seem to accommodate appropriately to negative energy balance in early lactation through rumen fermentation. 相似文献