Mathematical modelling of Atlantic salmon migration, foraging, and growth with long-term observational data and high-resolution 3D ocean models to...

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Mathematical modelling of Atlantic salmon migration, foraging, and growth with long-term observational data and high-resolution 3D ocean models to test hypotheses about how climate change, ocean currents, and plankton ecology come together to shape the salmon's past and futureAtlantic salmon are an important economic and cultural resource, whose life cycle relies upon ecological interactions across both freshwater and marine ecosystems. In recent decades populations of salmon have declined across their natural range. Marine surveys have indicated that post-smolt salmon from multiple southern European stocks coalesce at an oceanographic feature on the continental shelf edge (Wyville Thomson Ridge, WTR) in early summer prior to moving north towards their Arctic feeding grounds in the Norwegian Sea. Past this migratory convergence, salmon appear to enter one of two larger-scale current systems, the Norwegian coastal current or the central Norwegian Sea, but it is unclear how this decision, which may be of critical importance in shaping the outcome of their marine phase, is determined. This convergence at the WTR provides a common end point around which to organise resource modelling for salmon stocks from multiple start points (river mouths). By modelling interannual variation in prey fields across the continental shelf between the start points and end point of post-smolt migration, survival probability (as assessed through time series of salmon returns by river) might be mapped to prey fields and their environmental drivers (as assessed through Continuous Plankton Recorder zooplankton data, in conjunction with high-resolution ocean models). The main goal of this project is to develop an agent-based model for the 3-month post-smolt period, and to examine the importance of ocean transport systems and the resulting variability in prey fields in determining past patterns of survival. This project will contribute to a coordinated international efforts in determining mechanisms behind salmon mortality, and enable forecasting of survival prospects to guide management and direct policy.