Environmental productivity patterns of the Salish Sea: trends, impacts, projections

This project conducted in cooperation between UBC and the Pacific Salmon Foundation (PSF), supported by Mitacs and focused on environmental, food web, and human impacts on salmon productivity in the Salish Sea (the combined Strait of Georgia in BC and Puget Sound in Washington).

The background is that marine survival rates for Chinook and coho salmon in the Salish Sea have decreased since the 1970s, and the PSF cooperate with Long Live the Kings in Seattle to evaluate the potential causes of this decline. It is clear by now, that there is no simple explanation, no silver bullet – it’s likely to be a combination of factors. Ecosystem modeling can evaluate such factors, notably the relative impact of long-term changes in environmental, food web, and exploitation conditions, and how each contribute to marine survival.

We have found in other studies that variation in environmental productivity can be amplified through the food web. There may have been considerable decadal changes in primary production in the Salish Sea, though we do not have estimates yet. We hypothesize that the low marine survival is due to a combination of low productivity and high predation pressure, and that fisheries pressures have played a lesser role.

The aim of the project is to evaluate how important such productivity changes are for population trends as compared to food web effects and direct human impacts. The activity will be the first to estimate long-term spatial and temporal changes in environmental productivity, and the relative impact that the environment, food, competitors, predators and human impact may have had on marine survival.

A central part of the project is developing a hydrodynamic 3D model (GETM) for the Salish Sea, coupled with a biogeochemical model through FABM, and linked via a zooplankton model to food web (Ecopath) and IBM models. GETM (General Estuarine Transport Model) is an Open Source fully baroclinic ocean model with tidal flood.

The implementation on the modeling complex relies on Compute Canada’s facilities for the modeling complex with hydrodynamic, biogeochemical and food web models.

The project involves the following

Name Topic
Villy Christensen PI
Carl Walters Advisor & model development
Karsten Bolding GETM model support
Jorn Bruggeman FABM model support
Vijay Kumar GETM and FABM models
Greig Oldford EwE model
Jeroen Steenbeek EwE model
Joe Buszowski EwE model