Seasonality in the different dimensions of the sardine social-ecological system of the Bay of Biscay from habitat to fish to the fishery and to the canning industry. (a) Monthly climatology of the number of batches of sardine processed by 3 major canning industries in Brittany. The batches are affected by their fishing month and not their reception month (see text). (b) Monthly climatology of the total catches in the Bay of Biscay. Error bars represent ±1 standard deviation computed on the interannual variability. (c) Monthly climatology of the sardine fat content, with variability calculated from the monthly average values obtained from the different years and 3 canning industries. The red horizontal line draws the limit above which fish can be sold with a quality label in France (‘Label rouge’). The yellow curve represents seasonality in the number of sardine eggs from PNMI sampling. (d) Monthly climatology of the Bay of Biscay temperature (red) and zooplankton (green) concentration (2000–2024). Error bars represent ±1 standard deviation computed from the monthly averaged values obtained from the different years.