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31.
ABSTRACT

Little is known regarding the correlation between channel catfish female body weight and relative fecundity and fry production when the females are induced to ovulate with carp pituitary extract and fertilized with blue catfish sperm. A total of 145 female channel catfish were used in the early, middle, and late spawning season. Female body weight of channel catfish had negative correlations with relative fecundity (r = ?0.33 and ?0.25, P < .05; r = ?0.23, P > .05) and before the late spawning season with fry/kg (r = ?0.21, P > .05; r = ?0.30, P < .05). Eggs/kg female body weight and fry/kg female body weight followed a parallel pattern throughout the season, illustrating the logical relationship between relative fecundity and fry output. The size of females used is a consideration to maximize hybrid catfish embryo production during the early and middle spawning season but not late in the spawning season. However, these correlations are relatively small even though significant; thus a dramatic change in fry production would not be predicted. Since reproductive relationships can change during the spawning season, conclusions and recommendations could be flawed if data are not collected periodically during an entire spawning season.  相似文献   
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Hydroacoustic single fish detection and corresponding hydrographic measurements were used to study seasonal changes in vertical distribution of adult cod (Gadus morhua) in relation to ambient environmental conditions in the Bornholm Basin, central Baltic Sea. Sampling was conducted in April, June and August covering the years 2006–2009. Vertical distribution of individual fish was resolved from hydroacoustic single‐target detection in combination with a fish‐tracking algorithm and related to ambient hydrographic conditions. Based on a generalized linear effect model, both salinity and oxygen concentration were identified as key parameters affecting cod vertical distribution. Results also showed a clear seasonal effect with a more shallow distribution as the spawning season progressed and oxygen concentrations in the deep parts of the basin deteriorated. The upper limit of the distributional range was mostly constituted by the halocline and remained rather constant, whereas increasing oxygen depletion in the deep water layers lifted the lower boundary of the vertical distribution, leading to the observed upward shift in the overall distribution pattern. The results presented in this study highlight a significant shortcoming of the assessment survey design established for this species, as the observed shift in vertical distribution is not taken into account, thus introducing a potential bias into a data series used to tune the ICES standard stock assessment of this species.  相似文献   
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The marine ornamental industry relies almost exclusively on wild-caught fish, invertebrates, and live rock to meet the market demands of aquarium hobbyists. For the industry to expand, appropriate technologies are needed to mitigate disease problems and reduce the dependence on wild stocks. Biosecurity protocols and techniques for genetic improvement have recently been applied to the culture of penaeid shrimp for human consumption, and these approaches may be applicable to an emerging marine ornamental industry. Biosecure production systems for penaeid shrimp are being developed in response to disease problems and growing concerns about environmental pollution from pond effluent. Biosecure systems rely on minimal water exchange and provide shrimp farmers with an opportunity to move production away from the coastline. In addition to the development of biosecure production systems, researchers at the Oceanic Institute have established a selective breeding program for the Pacific white shrimp, Litopenaeus vannamei. To date, significant improvements in shrimp growth and disease resistance have been made through selective breeding. It is likely that advances in biosecure technologies and genetic improvement will be applicable to the culture of marine ornamental shellfish and finfish and will contribute to an economically viable and environmentally sustainable industry.  相似文献   
35.
A search was made for 26Mg (26Mg*) from the decay of 26Al (half-life = 0.73 million years) in Al-rich objects from unequilibrated ordinary chondrites. Two Ca-Al-rich inclusions (CAIs) and two Al-rich chondrules (not CAIs) were found that contained 26Al when they formed. Internal isochrons for the CAIs yielded an initial 26Al/27Al ratio [(26Al/27Al)0] of 5 x 10(-5), indistinguishable from most CAIs in carbonaceous chondrites. This result shows that CAIs with this level of 26Al are present throughout the classes of chondrites and strengthens the notion that 26Al was widespread in the early solar system. The two Al-rich chondrules have lower 26Mg*, corresponding to a (26Al/27Al)0 ratio of approximately 9 x 10(-6). Five other Al-rich chondrules contain no resolvable 26Mg*. If chondrules and CAIs formed from an isotopically homogeneous reservoir, then the chondrules with 26Al must have formed or been last altered approximately2 million years after CAIs formed; the 26Mg*-free chondrules formed >1 to 3 million years later still. Because 26Mg*-containing and 26Mg*-free chondrules are both found in Chainpur, which was not heated to more than approximately400°C, it follows that parent body metamorphism cannot explain the absence of 26Mg* in some of these chondrules. Rather, its absence indicates that the lifetime of the solar nebula over which CAIs and chondrules formed extended over approximately5 million years.  相似文献   
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Artificial insemination is widely used in the cattle industry and a major challenge is to ensure that semen is free of infectious agents. A healthy donor bull was tested for freedom from infectious agents. A bovine herpesvirus was isolated in testis cells and identified as bovine herpesvirus type 5 (BoHV-5) by polymerase chain reaction and by direct amplicon sequencing. The amplicon sequence shared 100% similarity with the published sequence of BoHV-5. This is the first report in Australia of BoHV-5 in semen. The implications of this finding are discussed.  相似文献   
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SUMMARY Mice trapped on farms in south-eastern Queensland had chronic abscessating osteoarthritides mainly involving the carpi and tarsi. Pleomorphic bacteria were shown by silver staining to be plentiful within lesions. Streptobacillus moniliformis was isolated from the joints, and streptobacillary polyarthritis was diagnosed. Other lesions observed included subcutaneous and hepatic abscesses.  相似文献   
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Summary A serological survey of 2160 Merino stud rams on 36 farms detected positive reactions greater than or equal to 1/100 in 42% of animals using the microscopic agglutination test (MAT) to Leptospira interrogans serovar hardjo. Twenty flocks had seroprevalence values greater than 30% with 15 flocks having values 60%. The enzymelinked immunosorbent assays showed that 47% and 3% of rams on the 36 farms were positive for IgG and IgM antibodies, respectively. Forty-five percent of hardjo reactions were in rams that had not been exposed to cattle. Significant correlations were found between IgM reactors and creek/dam water pumped into troughs, and between MAT/IgG reactors and total flock size. No statistical relationships were detected between positive reactors and two different annual average rainfall gradients, the time of the year in which samples were obtained, or agricultural regions of South Australia. Infections with an organism of the Sejroe serogroup is widespread in Merino stud rams.  相似文献   
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