UBC Theses and Dissertations
Environmental and physiological influences on the behaviour and survival of adult sockeye salmon during their coastal migration Drenner, Stephen Matthew
The reproductive migration of anadromous salmon through coastal waters is among the most challenging phases of their life cycle, yet our understanding of the mechanisms underlying this migration is limited. Thus, the objective of this thesis was to develop a better understanding of how environmental conditions and fish physiologic state influence behaviour and survival of homing anadromous salmon in coastal waters. Using a literature synthesis, I identified consistent behaviours across anadromous salmon species and life stages in marine waters including diel patterns and consistent swimming speeds. I further identified critical knowledge gaps, including a need for synchronized study of both environmental and physiological conditions. In field studies, I combined thermal data loggers, biotelemetry and physiological sampling and found that homing sockeye salmon exhibited diel and variable thermal experiences (8.4 °C to 20.5 °C) in coastal waters, potentially related to gaining cues for navigation. Sockeye salmon tended to follow coastlines and migration rate was related to wind patterns, salinity and fish physiological state. I propose that wind-induced currents exposed sockeye salmon entering the estuary to stronger olfactory cues associated with freshwater, which resulted in faster migration rates due to increased navigation ability or advanced reproductive maturity through a neuroendocrine response. Once migration neared freshwater, sockeye salmon used wind-induced currents to aid in movements, which may be associated with energy conservation. I further identified a genomic signature related to marine survival, which was associated with stress, immune response, metabolic processes, protein biosynthesis and osmoregulation. This genomic signature was similar to that identified in a previous study examining freshwater survival, but with an opposite relationship with survival, which I attribute to the attenuation of disease resistance of fish upon exposure to elevated river temperatures. Through the use of multiple research approaches, this thesis advances the biological understanding of the marine homing migration of sockeye salmon by empirically establishing novel relationships between environmental conditions, physiological state and sockeye salmon behaviour and survival in marine waters. In addition, this thesis is broadly applicable to other anadromous salmon, as well as to studies invoking a similar approach of physiological biotelemetry for studying animal movements.
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Attribution-NonCommercial-NoDerivs 2.5 Canada