Exploring the climate influence on sardine and sardinella species in northwest Africa from a novel end-to-end model strategy

Canary Upwelling System (CUS) is, together with California, Humboldt, and Benguela, one of the four main Eastern Boundary Upwelling Systems (EBUS) across the globe. In particular, small pelagic fishes (hereinafter SPF) dominate the marine biomass in EBUS where they represent a vital intermediate connection between plankton and large predatory species. Regarding the CUS, SPF constitute in weight close to 70% of the total landings of northwest African countries, being the Sardine pilchardus (hereinafter sardine) and the Sardinella aurita (hereinafter sardinella) the dominant SPF species in terms of abundance. The latter, for instance, is a primary source of animal protein in Senegal. However, the absence of systematic observations of sardine and sardinella across northwest Africa largely constraint our understanding of how the environmental variability impacts the abundance and distribution of these species. In this work a novel end-to-end (here climate-to-fish) model-based strategy, including explicit representation of sardine and sardinella dynamics within a common model framework, has been designed. With this approach the target species can compete and exploit the same ecosystem, allowing a consistent comparison of their respective responses to the environment. The resulting unified model for both sardine and sardinella allows us to better understand several links with well-known climate modes such as NAO and ENSO, which have been described by the authors in previous single-species-based analyses.