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A cycle of fluctuation in the Far Eastern sardine, Sardinops sagax, population is accompanied by an abrupt drop and recovery of fish size and lipid content of parent fish, which may reflect a phase variation from coastal to oceanic and its reverse. The cycle begins with the survival success of a smaller number of eggs produced by high-quality parents, which is triggered by a global climate change (density-independent process), and finally ends in the survival failure resulting from an overexpansion of an enormous number of fish produced by low-quality parents (density-dependent process). 相似文献
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Toshihiro NADE Kyouhei UCHIDA Kouhei OMORI Kenta MATSUBAYASHI Nobuhiro KIMURA 《Animal Science Journal》2012,83(4):310-317
Feeding dried distillers grains with solubles (DDGS) during the late stage of the fattening period of Holstein steers was studied in regard to the influence on meat quality. Sixteen Holstein steers approximately 18 months old were used in this study. Eight animals were fed commercial concentrated feed for the entire fattening period. The other eight animals were fed 15% DDGS in the concentrated feed for 3 months before slaughtering. The moisture, ether extract and crude protein from both groups was approximately the same. The thiobarbituric acid reactive substance (TBA) value of storage for 7 days at 5°C from the animals fed DDGS showed a tendency to be lower (P = 0.059). The change in the TBA value during storage was also lower for the animals not fed DDGS (P < 0.05). There were no differences in the subcutaneous fat color between the two groups. The a*(measure of redness) and b*(measure of yellowness) of the M. longissimus from the animals fed DDGS showed a tendency to be lower (P = 0.051, 0.070). The fatty acid composition of the M. longissimus, subcutaneous and perirenal fat were not widely influenced by the feeding of DDGS. It is suggested that feeding 15% DDGS during the late stage of the fattening period for Holstein steers reduced the oxidation of the beef. 相似文献
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ABSTRACT: The purpose of the present paper was to examine the size relationship between the juvenile stone flounder Platichthys bicoloratus and the bivalve Nuttallia olivacea , the siphon of which is important prey for the juvenile flounder. Juvenile stone flounder feed mainly on tips of the inhalant siphon of the bivalve. The maximum width of siphon tips in the stomach contents of age-0 fish could not reach that of age-1 fish, although the siphons in age-0 fish became larger as they grew. This size discrepancy indicated a limitation in the size of bivalves available to juveniles. The proportion of total cropping frequency for the siphon of the bivalve by juveniles was estimated according to the bivalve size class. Most bivalves that had cropped siphon tips ranged from 5 to 30 mm in shell length. The total cropping frequency per bivalve was particularly intense on bivalves of 10–25 mm shell length in spite of their small proportion of 24.9% of the total. This frequency intensity indicated that the size of bivalves with cropped siphons by juvenile stone flounder might depend on the ability of juveniles rather than the size composition of the bivalves. 相似文献
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ABSTRACT: The purpose of the present paper was to reveal the migration pattern of shirauo Salangichthys microdon Bleeker, in the Ishikari River system and its adjacent coastal sea areas. To this end, the strontium–calcium (Sr:Ca) ratios of the otoliths of 98 individuals were examined. Profiles of the Sr:Ca ratios during the life history after hatching in the estuary of the Ishikari River fell into two different patterns. One was characterized by a high (slightly fluctuating) Sr:Ca ratio throughout the life history; the other was characterized by an initial high Sr:Ca ratio followed by a lower value later in life. The former pattern was considered to be that of estuary–sea residents and the latter that of upstream migrants. Most upstream migrants migrated upstream once, although several did it twice. Back-calculated body lengths during the upstream and seaward migrations of the upstream migrants varied widely from 6.4 mm to 39.8 mm and from 13.5 mm to 79.4 mm, respectively. These findings suggest that estuary–sea residents and upstream migrants co-occurred spatiotemporally, and suggest a wide variation in migration patterns in the shirauo's life history. 相似文献
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ABSTRACT: We collected phytal animals (fauna associated with drifting seaweeds)off the Tohoku coast in northern Japan in May and June 1994 to examine their feeding habits. Phytal animals were assignedto the following three feeding habit groups: (i) carnivores preyingon crustaceans: a gammarid ( Stenothoe sp.) and a decapodmegalops; (ii) omnivores feeding on crustaceans and pinnate diatoms:a cirripede ( Lepas anserifera ), three gammarids ( Calliopius sp., Jassaslatteryi and J. marmorata ), an isopod ( Idotea metallica ),a decapod crustacean ( Planes cyaneus ), a decapod megalopsand two caprellids ( Caprella penantis and Caprella mutica );and (iii) herbivores grazing on pinnate diatoms, fucoids and seaweedsother than fucoids: three gammarids ( Allorchestes angusta , Amphithoelacertosa and Perampithoe lindbergi ), an isopod ( Cymodocejaponica ) and a polychaete ( Platynereis bicanaliculata ).Pinnate diatoms in the gut contents were composed mainly of Licmophora spp., Navicula spp., Nitzschia spp.and Cocconeis spp. and seaweeds other than fucoids (i.e. Ectocarpussiliculosus and Sphacelaria furcigera ). The latter twoalgae seemed to be epiphytes on drifting seaweeds. These resultssuggest that phytal animals play an important role in drifting seaweed communitiesthrough trophic linkage with two primary producers (i.e. driftingseaweeds and the epiphytes growing on them). 相似文献
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ABSTRACT: Baited traps were used over 24 h to reveal the diel activity and vertical distribution of three dominant lysianassoid amphipods ( Scopelocheirus onagawae , Anonyx omorii , Anonyx abei ) in Onagawa Bay, north-eastern Japan. The three species were the most dominant small crustacean scavengers in the bay. Most individuals were caught by traps deployed 0.3 m above the bottom, showing that they were active in the layers close to the sea bottom. No habitat segregation was found among species or developmental stages, suggesting that these scavengers rely on the food supply from bottom deposits. The three species increased remarkably in numbers of collected individuals at night, showing a rise in feeding activity. The two Anonyx species were collected only during the night, and S. onagawae was collected mostly during the night. The nocturnal activity appears to be an adaptation to reduce predation risks. However, juveniles of S. onagawae appeared even during the day, suggesting that feeding might take precedence over avoiding predation. Baited traps collected ovigerous females of S. onagawae but not of Anonyx species; the reason for the difference could not be determined. 相似文献
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Y. MIYAKOSHI H. HAYANO H. OMORI & M. NAGATA J. R. IRVINE 《Fisheries Management and Ecology》2002,9(4):217-223
Densities of wild masu salmon, Oncorhynchus masou Brevoort, were investigated before (late-September) and after (mid-November) autumnal habitat shifts in a small river in Hokkaido, northern Japan. Abundance of instream cover habitat formed by coarse woody debris, submerged vegetation and undercut banks was quantified. Density of 1+ and older masu salmon was significantly correlated with cover abundance in autumn, although cover was not significant for density of 0+ fish, indicating that clear-cut reaches were utilized by 0+ masu salmon in autumn. In early winter, densities of 0+ and 1+ and older masu salmon were both correlated with cover availability. These results suggest that the amount of cover habitat is an important regulator for densities of juvenile masu salmon during winter. 相似文献
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Yukiko ITO Shinji TOKI Takashi OMORI Hiroshi IDE Ryuichi TATSUMI Jun-ichi WAKAMATSU Takanori NISHIMURA Akihito HATTORI 《Animal Science Journal》2004,75(1):59-65
The solubility of skeletal muscle myofibrillar proteins in water was examined. The solubility of the proteins was found to be sensitive to ionic strength and pH of the solution. At the ionic strength of less than 12 mM and neutral pH, more than 80% of myofibrillar proteins were solubilized. Heating at a temperature of more than 70°C was required for the proteins to retain their solubility. The solubility of freeze‐dried protein powder prepared from water‐soluble myofibrillar proteins was also examined, and it was found that addition of trehalose and heating were essential for re‐solubilization in water. Amino acid composition of water‐soluble myofibrillar proteins was found to be almost the same as that of myofibrillar proteins. 相似文献
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