Physiological Drivers of Adult Salmon Migrations and Consequences of Different Migration Behaviour

Salmonid migrations represent one of the most complex and intriguing biological phenomena in the animal kingdom. Telemetry has been used extensively to describe movement and survival patterns associated with these migrations but by itself cannot inform the mechanisms underlying behaviour or causes of mortality. We summarize advances that have been made in understanding the migrations of adult Pacific salmon through the integration of broad-scale telemetry systems with disciplines including physiology, behaviour, functional genomics, and experimental biology. Record high temperatures, changing ocean conditions, disease, fisheries and other factors are threatening several populations, and challenging management systems. We overview intervention experiments and telemetry field approaches used to examine these issues for adult Fraser River sockeye salmon and explore hypotheses about recent changes in salmon behaviour and mortality.  We have found that fish health, physiological and reproductive state, physiological stress, and fisheries-handling all play key roles in migratory survival.  In addition to uncovering fascinating insights into the basic biology of salmonids, these results provide important information for fisheries managers in dealing with climate warming and capture-release fisheries.