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During the past 30 years bull trout (Salvelinus confluentus ) populations have declined in various watersheds across their range. The decline has been attributed to loss of habitat, over harvesting, habitat disturbance from resource development activities, and interaction with exotic species. The declining population trends observed over the past three decades suggest that this species is sensitive to impacts. In response to these declines, bull trout are listed as "Threatened" in the United States and "Sensitive" in Alberta, British Columbia, and the Yukon Territory. In the Northwest Territories bull trout are listed as "May Be at Risk" and are a candidate for a detailed risk assessment in the area. The presence...
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Pilfering is thought to play a role in the evolution of scatter-hoarding strategies; but is not well understood in larder-hoarding animals. I studied intraspecific pilfering in red squirrels in Kluane, YT, Canada. The purpose of this project was to estimate the natural rate of cache pilferage, and to examine variation in pilfering behaviour. Results from experimental removal of territory owners, suggested that younger squirrels with smaller food caches were more likely to pilfer when given the opportunity. Survival over-winter was dependent on the number of cones cached and pilfering squirrels were less likely to survive. Using a mark-recapture study of marked cones I found that few individuals (14%) did any pilfering...
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Riverine sockeye salmon Oncorhynchus nerka (those that do not use nursery lakes for juvenile rearing) tend to be characterized by greater genetic diversity and weaker population structure than lake-type populations. These findings have led to the 'recurrent evolution' hypothesis for sockeye salmon life histories, which proposes that riverine sockeye salmon are the principal colonizing form and play the dominant role in the long-term persistence of sockeye salmon in a dynamic landscape. However, previous studies in Kamchatka (Russia) and Alaska have suggested that the general patterns of riverine sockeye salmon do not apply in all parts of the species' range. In this study, we examined genetic diversity and population...
Populations of Chinook salmon Oncorhynchus tshawytscha in the Yukon River declined by more than 57% between 2003 and 2010, probably the result of a combination of anthropogenic and environmental factors. One possible contributor to this decline is Ichthyophonus, a mesomycetozoan parasite that has previously been implicated in significant losses of fish, including Chinook salmon. A multiyear epidemiological study of ichthyophoniasis in the Yukon River revealed that disease prevalence and Chinook salmon population abundance increased and decreased simultaneously (i.e., were concordant) from 1999 to 2010. The two values rose and fell synchronously 91% of the time for female Chinook salmon and 82% of the time for males;...
Toxaphene is one of the major persistent organic pollutants with global environmental impacts. We have measured total toxaphene and specific congeners concentrations in 19 fish samples collected from the Yukon, Canada using gas chromatography coupled to ion trap MS/MS. The total toxaphene concentrations ranged from 42 to 242 ng/g (mean = 107+/-61 ng/g). The sum of the three specific congeners (Parlar 26, 50 and 62) was within 10-55 ng/g. The ratio of the sum of the three congeners to the total toxaphene varied between 8% and 25% in the fish samples but the ratio may be species specific. Our results suggest that consumption of these Yukon fish should have minimal risk of toxaphene exposure.
Understanding processes and mechanisms resulting in observed ecological patterns is critical information for biologists charged with effectively managing and conserving wildlife populations. In many areas across North America woodland caribou (Rangifer tarandus caribou Gmelin) populations are declining, as are caribou and reindeer populations globally. Why these declines are occurring is a key research question of biologists and managers. I investigated factors influencing recruitment of mountain-dwelling woodland caribou using long-term time series from ten herds (populations) in the Yukon Territory, Canada (Yukon). Recruitment was indexed by the calf:cow ratio observed during the fall breeding season using data...
map background search result map search result map Intraspecific cache pilferage by larder-hoarding red squirrels (Tamiasciurus hudsonicus) in Kluane, Yukon Distribution, life history, and habitat use of bull trout ( Salvelinus confluentus) in mountain streams of the southern and central Northwest Territories Lake characteristics and species inventory and distribution for 11 Interior Alaska lakes, 2005-2008 Genetic Diversity and Population Structure in the Kuskokwim River Drainage Support the Recurrent Evolution Hypothesis for Sockeye Salmon Life Histories The ecology of snowshoe hares in northern boreal forests Predation on moose and caribou by a regulated wolf population Is the relationship between predator and prey abundances related to climate for lynx and snowshoe hares? Evaluation of wolf density estimation from radiotelemetry data Arctic ground squirrel population collapse in the boreal forests of the Southern Yukon Predicting origins of passerines migrating through Canadian migration monitoring stations using stable-hydrogen isotope analyses of feathers: a new tool for bird conservation Intraspecific cache pilferage by larder-hoarding red squirrels (Tamiasciurus hudsonicus) in Kluane, Yukon Is the relationship between predator and prey abundances related to climate for lynx and snowshoe hares? Arctic ground squirrel population collapse in the boreal forests of the Southern Yukon Evaluation of wolf density estimation from radiotelemetry data Lake characteristics and species inventory and distribution for 11 Interior Alaska lakes, 2005-2008 Distribution, life history, and habitat use of bull trout ( Salvelinus confluentus) in mountain streams of the southern and central Northwest Territories The ecology of snowshoe hares in northern boreal forests Predation on moose and caribou by a regulated wolf population Genetic Diversity and Population Structure in the Kuskokwim River Drainage Support the Recurrent Evolution Hypothesis for Sockeye Salmon Life Histories Predicting origins of passerines migrating through Canadian migration monitoring stations using stable-hydrogen isotope analyses of feathers: a new tool for bird conservation