Will most suitable spawning grounds for coastal fishes be impacted by climate change? A larval drift modelling approach
Résumé
For many fishes, the larval drift ensures a passive transport by currents between spawning areas and coastal nurseries, but also potential dispersal towards new habitats. As such, species have developed strategies to enhance the recruitment success, including the selection of appropriate spawning grounds. Two main strategies are possible: either the location of spawning areas is stable over years, corresponding to sites with good reproduction success in average, or fishes use environmental cues to select the most appropriate spawning sites each year. However, increased temperature due to climate change may lead to changes in hydrodynamics, shorter larval drifts, and earlier egg laying. As such, the most suitable strategies may change. Hydrodynamic models coupled with individual based models are often used and have proved to be relevant tools to study larval drift. However, these complex models require many parameters, many of which are uncertain, making a comprehensive sensitivity analysis a crucial first step. This study focused on five commercially important fish species (with contrasted spawning strategies and larval ecology) present all over Western Europe, from the Iberian coast to the North Sea. We began by assessing the relative influence of extrinsic and intrinsic parameters and their uncertainty on results of larval drift. Then, the model was used to evaluate if the location of the most favourable spawning areas (allowing higher rates of larvae reaching coastal nurseries) was stable over time, and if differences could be found in “warm” or “cold” year archetypes.