Quantitative recovery planning: understanding how human activities in watersheds can influence population dynamics and genetic structuring of diadromous fishes.

• Main Author: Bowlby, Heather Dawn
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2016
• Subjects: Atlantic salmon
• Online Access: https://research.library.mun.ca/12529/; https://research.library.mun.ca/12529/1/thesis.pdf

Developing quantitative relationships that link human-induced environmental change with changes in population dynamics for species of conservation concern is hindered by: (1) a limited understanding of the cumulative effect (and relative importance) of population regulation, spatial dynamics, and demographic processes, (2) issues with detectability for species-environment interactions owing to data characteristics and (3) the cumulative or confounding nature of multiple threats. Taking a single-species approach based on endangered Atlantic salmon, I have partially addressed these challenges in my four research chapters. In chapter two, I characterized the conditions under which metapopulation structure would be expected to benefit a population assemblage and found that straying can reduce abundance and heighten extinction risk when productivity is low. For species of conservation concern, I would expect that remediation actions designed to influence demographic rates (e.g. mortality rates) would be more beneficial than actions influencing spatial dynamics. In chapter three, I accounted for the effects of observation and measurement error when quantifying relationships between hydrological variation and survival. Beyond the potential to change our interpretation of ecological relationships, I was able to infer the types of threats affecting juveniles in specific watersheds. In chapter four, I used patterns of effective dispersal to surmise the behavioural mechanism leading to watershed choice among straying adult salmon as well as the relative importance of multiple concurrent threats. My conclusions contradict some current perceptions on threats and suggest new directions for future research. In chapter five, I was able to develop a spatial tool that could inform management decisions or identify priority areas for restoration efforts. However, I was unable to fully characterize how environmental variation influences habitat utilization, distribution patterns, or population-level responses to human activities at ...