Impacts of climate change on the complex life cycles of fish

Abstract To anticipate the response of fish populations to climate change, we developed a framework that integrates requirements in all life stages to assess impacts across the entire life cycle. The framework was applied on plaice ( P leuronectes platessa ) and Atlantic herring ( C lupea harengus ) in the N orth S ea, A tlantic cod ( G adus morhua ) in the N orwegian/ B arents S eas and E uropean anchovy ( E ngraulis encrasicolus ) in the B ay of B iscay. In each case study, we reviewed habitats required by each life stage, habitat availability, and connectivity between habitats. We then explored how these could be altered by climate change. We documented environmental processes impacting habitat availability and connectivity, providing an integrated view at the population level and in a spatial context of potential climate impacts. A key result was that climate‐driven changes in larval dispersion seem to be the major unknown. Our summary suggested that species with specific habitat requirements for spawning (herring) or nursery grounds (plaice) display bottlenecks in their life cycle. Among the species examined, anchovy could cope best with environmental variability. Plaice was considered to be least resilient to climate‐driven changes due to its strict connectivity between spawning and nursery grounds. For plaice in the N orth S ea, habitat availability was expected to reduce with climate change. For N orth S ea herring, N orwegian cod and B iscay anchovy, climate‐driven changes were expected to have contrasting impacts depending on the life stage. Our review highlights the need to integrate physiological and behavioural processes across the life cycle to project the response of specific populations to climate change.