Migration Model of Post-Smolt Atlantic Salmon (Salmo salar)

Understanding how oceanographic factors independently and interactively influence migratory fish behavior, physiology, and survival is essential to predicting the impact of climate change on fish. We used Ocean Tracking Network data to inform a novel modeling approach that combines an individual-based particle model with a bioenergetics model to evaluate the effects of oceanographic variability on migration of post-smolt Atlantic salmon (Salmo salar). Interannual variability in the surface current velocity and sea surface temperature differentially influenced migration. The magnitude, duration and direction of the currents relative to a fish’s intended swimming direction had the strongest influence on migration. Changes in ocean circulation led to changes in currents at a regional scale that have a similar, relative effect across multiple populations during out-migration. Results of this study suggest that the Nova Scotia Coastal Current (NSCC) has a strong influence on the pathways of migrating salmon through the Gulf of Maine. The influx of cool Arctic fresh water, observed in the early 1990’s, changed the NSCC and, as suggested by model results, could have dramatically influenced post-smolt salmon migration success. There was a trade-off between arriving at the destination quickly but at a small size and not arriving at the destination at all.