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Seminar Series
All seminars are held in the main conference room at the Columbia River Fisheries Program Office. Click here for directions or call 360-604-2500 for more information. Understanding the links between demographic processes and the environment in which populations exist is a central component of endangered species conservation. Because of their threatened status, considerable research has been conducted to evaluate factors affecting bull trout populations. Past research indicates that population declines can largely be attributed to habitat loss and fragmentation, introduction of non-natives, and overexploitation. However, critical knowledge gaps still exist with regards to factors limiting survival during early life stages, dispersal rates among populations, and an overall understanding of how populations interact. We focused research on these lesser-known components of the bull trout life cycle via a combination of mark-recapture observations, field experiments, and population modeling based on long-term data from multiple populations. Our research on reproductive success suggests that survival of bull trout eggs and larvae can be highly variable and is negatively related to percent fine sediment and positively related to downwelling within individual redds. We used mark-recapture data to quantify juvenile survival rates, assess movement patterns, and estimate dispersal probabilities among spawning populations. Bull trout frequently traveled >40 km from the point of initial capture, and a few individuals from one natal stream migrated into a different natal habitat to spawn. We integrated this movement data into a metapopulation model based on observed demographic characteristics from a data-rich population, which we used to assess the importance of dispersal rates and distances on population persistence. This research highlights the value of a multi-scale approach to understanding factors limiting imperiled populations, and helps improve our understanding of some critical components of the bull trout life cycle.
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