Time series of indices of the sardine social-ecological system in the Bay of Biscay between 2000 and 2024. Mesozooplankton dry weight in May in the range of (a) 0.2–0.5 mm, (b) 1–2 mm, and (c) 0.2–2 mm. Boxplots are produced based on block data after spatial smoothing of the raw data from survey stations. (d) Sardine mean length at age and mean individual length (black); (e) sardine mean weight at age and mean individual weight (black); and (f) sardine proportion at age based on the abundance in May during the PELGAS survey, a linear trend is plotted for age 1 only. (g) Sardine fat content as measured by the canning industry averaged over the months July to October. (h) Spawning stock biomass and (i) fishing mortality from stock assessment. (j) Number of vessels targeting sardine by fleet, (k) income dependency to sardine with respect to the total annual income, and (l) share of sardine income generated in the ‘low’ season (December to May). (m) Price of sardines (in constant 2015 euros) at first sale in auction market or when imported frozen, (n) national import of sardines canned, frozen, or fresh; and (o) French consumption of fresh or canned sardines. Linear trends are plotted when significant at the threshold p-value = 0.05, with slope provided in Table 1. Note that in 2020 PELGAS could not occur because of COVID.