UBC Theses and Dissertations
Distribution, habitat use, and migratory life history of Southern Dolly Varden (Salvelinus malma lordi) in a salmon-bearing watershed on the Central Coast, British Columbia Heavyside, Julian
Anadromous freshwater fishes are among the most threatened vertebrates in North America. Population declines and collapses due to overfishing, habitat loss, and climate change have long been documented for socioeconomically important salmonids such as Pacific salmon (Oncorhynchus spp), but the conservation status of other species such as Dolly Varden char (Salvelinus malma) remains largely unknown. Even without the pressures of direct commercial harvest, many anadromous salmonids may still be vulnerable to the other threats faced by commercially-harvested species, but conservation efforts continue to be hampered by a lack of basic life history and demographic information. While the Northern Dolly Varden (S. m. malma) has been assessed as “Special Concern” by the Committee on the Status of Endangered Wildlife in Canada, the Southern Dolly Varden (S. m. lordi) has received little conservation attention despite near ubiquity in coastal watersheds from Alaska to Washington, partly due to a lack of data throughout the broad coastal range. I conducted surveys on a population of Southern Dolly Varden in a lake-headed coastal watershed on the mid coast of British Columbia to identify key spawning, rearing, and foraging habitat, to characterize seasonal patterns in their iteroparous anadromous migratory life history, and to assess the extent of migratory coupling among Pacific salmon and Dolly Varden throughout the year. I found that Dolly Varden used a wide range of habitats distributed throughout the entire watershed, and that there were distinct seasonal movements that were temporally associated with Pacific salmon migrations. My observations indicate that this population of Southern Dolly Varden requires the entire extent of the watershed, from lake tributaries to the estuarine river mouth, for individuals to express their complete migratory life history, and that this population is vulnerable to any disturbance leading to the degradation or loss of access to key habitats for spawning, rearing, and foraging. This population could serve as a baseline for understanding the conservation status of Southern Dolly Varden throughout the rest of the range, and can be used as a rare model for studying predator-prey migratory coupling as it relates to socioeconomically important species of Pacific salmon.
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