Sole larval supply to coastal nurseries: Interannual variability and connectivity at interregional and interpopulation scales

• We simulated the drift trajectories of sole eggs and larvae at large spatial (four stocks) and temporal (26 y) scales;
• We used an IBM coupled online to a hydrodynamic model;
• We emphasized:
• The very low to moderate connectivity between populations at the larval stage
• The moderate influence of spawning biomass variations on recruitment
• The influence of life history and climate variability on the amount of settled sole.

Simulating fish larval drift helps assess the sensitivity of recruitment variability to early life history. An individual-based model (IBM) coupled to a hydrodynamic model was used to simulate common sole larval supply from spawning areas to coastal and estuarine nursery grounds at the meta-population scale (4 assessed stocks), from the southern North Sea to the Bay of Biscay (Western Europe) on a 26-yr time series, from 1982 to 2007. The IBM allowed each particle released to be transported by currents, to grow depending on temperature, to migrate vertically depending on development stage, to die along pelagic stages or to settle on a nursery, representing the life history from spawning to metamorphosis. The model outputs were analysed to explore interannual patterns in the amounts of settled sole larvae at the population scale; they suggested: (i) a low connectivity between populations at the larval stage, (ii) a moderate influence of interannual variation in the spawning biomass, (iii) dramatic consequences of life history on the abundance of settling larvae and (iv) the effects of climate variability on the interannual variability of the larvae settlement success.