Mortality and recovery of runt white sturgeon (Acipenser transmontanus) in a commercial farm in California, USA     

Georgiadis MP  Hedrick RP  Johnson WO  Gardner IA 《Preventive veterinary medicine》2000,43(4):269-281

We investigated the effect of raising runt white sturgeon (Acipenser transmontanus) separately from dominant fish during the initial stages of grow-out in a commercial farm. Runt fish are poor-growers, have underdeveloped muscle mass, swim slowly and are more-frequently found at the top of the water column. The objective of the study was to describe the mortality and recovery rates (and their determinants) of white-sturgeon runts after separating them from dominant fish. Runt white sturgeon were stocked into twelve 2 m × 2 m rectangular tanks and graded periodically during a follow-up of 46–102 days. Overall mortality rates ranged from 0.3 to 7 dead fish per 1000 sturgeon-days at risk and overall recovery rates from 3.9 to 13.5 recovered fish per 1000 sturgeon-days at risk. Period-specific mortality and recovery rates increased over time. The period-specific mortality rates for all three periods were significantly higher for tanks of runts originating from grow-out tanks with high mortality (p-values: first period = 0.06; second period = 0.09; third period = 0.03), but were similar for tanks of runts of high- and low-mean initial weight. The period-specific recovery rates were significantly higher in runts originating from high-mortality grow-out tanks only for the third period (p = 0.05) but not the first and second periods (p-values = 0.33 and 0.25, respectively). Recovery rates were significantly higher in the higher-mean-weight runts tanks for the first and third period but not for the second (p-values: first period = 0.02; second period = 0.65; third period = 0.06). We concluded that the proportion of runts that recover during a 46–89 day period is substantial (16–58%); therefore, it might be worthwhile growing such fish separately in a fish farm for about three months. Financial analysis showed that this practice was profitable, if the value of white sturgeon fish for the farm exceeded $2.05 per kg.  相似文献   

Use of age and milk production data to improve the ability of enzyme-linked immunosorbent assay test results to predict Mycobacterium avium ssp. paratuberculosis fecal culture status.     

Roy D Berghaus  Thomas B Farver  Randall J Anderson  John M Adaska  Ian A Gardner 《Journal of veterinary diagnostic investigation》2006,18(3):233-242

Cows from 2 California dairies were tested for paratuberculosis at the end of lactation by using fecal culture and a commercially available serum enzyme-linked immunosorbent assay (ELISA) test kit. Individual cow characteristics and production variables were evaluated along with ELISA testing results as predictors of fecal culture status. In multivariable logistic regression analysis, age and a herd-standardized version of 305-day mature equivalent (305 ME) milk production were significant predictors of fecal culture status after adjusting for herd, quarter of the study year, and ELISA sample-to-positive (S/P) ratio. The area under a nonparametric receiver operating characteristic curve was significantly greater for a multivariable model that included age and the level of milk production when compared with a model without these covariates. In conclusion, consideration of cow-level covariates was useful as an aid in predicting Mycobacterium avium ssp. paratuberculosis (MAP) fecal culture status. For a given ELISA S/P ratio, older cows and those with lower 305 ME milk production relative to other cows in the herd were significantly more likely to be shedding MAP in their feces at the end of lactation.  相似文献   

World Watch     

Gardner Murray 《Australian veterinary journal》2006,84(5):N20-N20

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World Watch     

Gardner Murray 《Australian veterinary journal》2006,84(6):N25-N25

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Comparison of the Sensitivity of Landscape-fire-succession Models to Variation in Terrain, Fuel Pattern, Climate and Weather   总被引：1，自引：0，他引：1  

Geoffrey J. Cary  Robert E. Keane  Robert H. Gardner  Sandra Lavorel  Mike D. Flannigan  Ian D. Davies  Chao Li  James M. Lenihan  T. Scott Rupp  Florent Mouillot 《Landscape Ecology》2006,21(1):121-137

The purpose of this study was to compare the sensitivity of modelled area burned to environmental factors across a range of independently-developed landscape-fire-succession models. The sensitivity of area burned to variation in four factors, namely terrain (flat, undulating and mountainous), fuel pattern (finely and coarsely clumped), climate (observed, warmer & wetter, and warmer & drier) and weather (year-to-year variability) was determined for four existing landscape-fire-succession models (EMBYR, FIRESCAPE, LANDSUM and SEM-LAND) and a new model implemented in the LAMOS modelling shell (LAMOS(DS)). Sensitivity was measured as the variance in area burned explained by each of the four factors, and all of the interactions amongst them, in a standard generalised linear modelling analysis. Modelled area burned was most sensitive to climate and variation in weather, with four models sensitive to each of these factors and three models sensitive to their interaction. Models generally exhibited a trend of increasing area burned from observed, through warmer and wetter, to warmer and drier climates with a 23-fold increase in area burned, on average, from the observed to the warmer, drier climate. Area burned was sensitive to terrain for FIRESCAPE and fuel pattern for EMBYR. These results demonstrate that the models are generally more sensitive to variation in climate and weather as compared with terrain complexity and fuel pattern, although the sensitivity to these latter factors in a small number of models demonstrates the importance of representing key processes. The models that represented fire ignition and spread in a relatively complex fashion were more sensitive to changes in all four factors because they explicitly simulate the processes that link these factors to area burned. The US Government's and the Canadian Government's right to retain a non-exclusive, royalty-free license is acknowledged  相似文献   

Neutral models for testing landscape hypotheses   总被引：5，自引：0，他引：5  

Robert H. Gardner  Dean L. Urban 《Landscape Ecology》2007,22(1):15-29

Neutral landscape models were originally developed to test the hypothesis that human-induced fragmentation produces patterns distinctly different from those associated with random processes. Other uses for neutral models have become apparent, including the development and testing of landscape metrics to characterize landscape pattern. Although metric development proved to be significant, the focus on metrics obscured the need for iterative hypothesis testing fundamental to the advancement of the discipline. We present here an example of an alternative neutral model and hypothesis designed to relate the process of landscape change to observed landscape patterns. The methods and program, QRULE, are described and options for statistical testing outlined. The results show that human fragmentation of landscapes results in a non-random association of land-cover types that can be describe by simple statistical methods. Options for additional landscape studies are discussed and access to QRULE described in the hope that these methods will be employed to advance our understanding of the processes that affect the structure and function in human dominated landscapes.  相似文献   

Sectional notes     

E. Marx  A. H. Eddins  G. D. Ruehle  H. L. Cochran  A. C. Moreau  J. V. Pace  Marx Koehnke  J. C. Campbell  M. E. Gardner  E. R. Jackman  C. A. Henderson  K. W. Lauer  C. N. Clayton  John Noonan  D. H. Friend  G. S. Ralston  H. M. Darling 《American Journal of Potato Research》1943,20(4):95-106

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Sectional notes     

Cecil W. Frutchey  Geo D. Ruehle  John S. Gardner  Verne C. Beverly  Marx Koehnke  John C. Campbell  H. J. Evans  C. A. Henderson  Harold S. Schaad  J. W. Scannell  R. E. Goodin 《American Journal of Potato Research》1947,24(12):419-425

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Sectional notes     

J. H. Heckman  H. G. Zuckerman  C. H. Metzger  W. B. Ward  John S. Gardner  Frank W. Hussey  Ralph W. Donaldson  A. G. Tolaas  K. H. Fernow  E. V. Hardenburg  W. G. Been  Robert Schmidt  E. M. Gillig  E. B. Tussing  K. W. Lauer  K. H. Klages  Brooks D. Drain  H. L. Bailey  J. G. Milward 《American Journal of Potato Research》1935,12(7):196-204

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Crop and market news Potato Markets Show December Dullness     

John S. Gardner 《American Journal of Potato Research》1926,3(12):384-388

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