Threats to at-risk salmonids of the Canadian Rocky Mountain region     

R. Niloshini Sinnatamby  Ariane Cantin  John R. Post 《Ecology of Freshwater Fish》2020,29(3):477-494

Trout and charr, members of the salmonid family, have high conservation value but are also susceptible to anthropogenic threats in part due to the specificity of their habitat requirements. Understanding historical and future threats facing these species is necessary to promote their recovery. Of freshwater trout and charr in the Canadian Rocky Mountain region, westslope cutthroat trout (Oncorhynchus clarkii lewisi), bull trout (Salvelinus confluentus; a charr species) and Athabasca rainbow trout (Oncorhynchus mykiss) are of conservation concern. And indeed, range contractions and declining populations are evident throughout much of their ranges. Range contraction was most evident in the southern Alberta designatable unit (DU) of westslope cutthroat trout. Diminished populations were also evident in the downstream watersheds of the Alberta bull trout range, and throughout the Athabasca rainbow trout range. We assessed historical and future threats to evaluate the relative importance of individual threats to each DU and compare their impact among species. Individual threats fall into the broad categories of angling, non-native species and genes, habitat loss and alteration, and climate change. Severity of each threat varies by DU and reflects the interaction between species’ biology and the location of the DU. Severity of threats facing each DU has changed over time, reflecting extirpation of native populations, changes in management and industry best practices, expansion of non-native species and progressing climate change. The overall threat impact for each DU indicates a high probability of substantial and continuing declines and calls for immediate action.  相似文献   

Beaver dams,streamflow complexity,and the distribution of a rare minnow,Lepidomeda copei          下载免费PDF全文

Daniel C. Dauwalter  John D. Walrath 《Ecology of Freshwater Fish》2018,27(2):606-616

Freshwater fishes are threatened globally, and often too little is known about threatened species to effectively guide their conservation. Habitat complexity is linked to fish species diversity and persistence, and degraded streams often lack habitat complexity. Beaver Castor spp., in turn, have been used to restore streams and increase habitat complexity. The northern leatherside chub Lepidomeda copei is a rare, small‐bodied, drift‐feeding minnow that has anecdotally been observed to use complex habitats associated with beaver dams in the western United States. To investigate this anecdote, we conducted fish and habitat surveys, the latter focusing on quantifying habitat complexity, in a sub‐basin of the Upper Snake River Basin in the USA. Complementary generalised linear model and path analyses revealed that northern leatherside chub occurred more often at sites with complex streamflows, and streamflows were more complex when beaver dams were present and pools were deeper. Northern leatherside chubs were also more likely to occur when temperatures were warmer, aquatic macrophytes were abundant and stream channels were narrow and deep. The linkage between chubs, complex streamflows and beaver dams needs to be evaluated more broadly to completely understand its role in the rangewide status of the species. However, it does suggests that increased use of beaver reintroductions and dam analogues for stream restoration could be a boon for the northern leatherside chub, but such efforts should be monitored to determine their effectiveness to help adapt beaver‐based restoration approaches to best benefit the species.  相似文献   

Digital mapping of soil salinity at various depths using an EM38     

Bhaskar Narjary  Murli Dhar Meena  Satyendra Kumar  Sushil Kumar Kamra  Dinesh Kumar Sharma  John Triantafilis 《Soil Use and Management》2019,35(2):232-244

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一种面向育种家的新型台式棉籽脱绒机     

杨子山 《中国棉花》2017,44(10):27-27

正棉籽酸脱绒会危害育种家人身安全和潜在环境。需要1种无需用酸,能有效去除棉短绒且对棉种萌发无不利影响的脱绒方法。为了优化棉籽机械脱绒流程,美国农业部农业研究中心(USDA-ARS)棉花生产与加工部门(Lubbock,Texas)研发创制了一台棉籽机械脱绒样机(图1,图2)。测试设计了应用7种滚筒衬垫(1种是不用任何研磨材料,其余6种分别采用不同的研磨材料)、1个或2个辊刷"擦  相似文献   

Quality Assurance Handbook for Veterinary Laboratories          下载免费PDF全文

John H. Lumsden 《The Canadian veterinary journal. La revue veterinaire canadienne》2001,42(7):567

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RADIOGRAPHIC DIAGNOSIS TRAUMATIC RETICULOPERITONITIS     

JoAnna  G. Toenniessen  DVM  John M.  Losonsky  DVM  MS 《Veterinary radiology & ultrasound》1994,35(1):22-23

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Disinfection in Veterinary and Farm Practice          下载免费PDF全文

John F. Prescott 《The Canadian veterinary journal. La revue veterinaire canadienne》1989,30(4):358-359

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The effect of body condition, live weight, breed, age, calf performance, and calving date on reproductive performance of spring-calving beef cows.     

K Osoro  I A Wright 《Journal of animal science》1992,70(6):1661-1666

Data from 321 spring-calving cows (mean calving date March 27) were used to assess the effects of body condition, live weight, cow age (from 4 to 13 yr), and breed (237 Hereford x Friesians and 84 Blue-Greys) and time of calving on the proportion of cows that became pregnant, the number of days from the start of mating to pregnancy, and calving interval. Mating started at turn-out to pasture in mid-May and lasted 9 to 10 wk. Body condition at calving and breed were the most significant animal factors affecting reproductive performance. Cows calving in higher body condition had shorter (P less than .001) calving intervals (11.2 d per unit of body condition at calving). Blue-Grey cows became pregnant in a higher proportion (90%) and calving interval was shorter (364 d) than in Hereford x Friesians (83%; 374 d). Body condition at the start of mating was less important and body condition at the end of mating had no effect. Live weight at calving and changes in live weight from calving to the start of mating and during the mating period had no significant effect. The proportion of cows becoming pregnant decreased significantly with age in Hereford x Friesian cows older than 7 yr. The variance in calving interval accounted for by calving date, body condition at calving, breed, and age was 42%.  相似文献   

母体外激素对仔猪断奶后行为的影响   总被引：1，自引：0，他引：1  

宋晓光  John Goihl 《国外畜牧学(猪与禽)》2003,23(3):46-47

猪嗅觉系统高度发达 ,有多种外激素都能调节猪的行为和生理。外激素是动物分泌的一种化合物 ,它能影响其它动物个体的行为和生理。外激素还传递个体、性别或其它识别模式的信息。还有证据表明 ,母体外激素可调节哺乳仔猪的行为。行为学研究结果表明 ,用溶剂将泌乳母猪皮肤上的气味洗去 ,仔猪就会拒绝哺乳 ,还证明了仔猪会被粪便中或其他生物液体中的母体气味所吸引 ,并且会区分这些物质中的母体气味。Pageat(2 0 0 1)分离到了哺乳动物的皮肤分泌物 ,研制出了与母猪皮肤分泌物成分相类似的脂肪酸混合物。据认为 ,这种混合物中可能含有母体外…  相似文献   

Poultry     

C. L. Wright 《Tropical animal health and production》1991,23(2):102-102

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