Major changes in sardine growth and body condition in the Bay of Biscay between 2003 and 2016: Temporal trends and drivers

•Both seasonal and inter-annual variability in body condition strongly depend on age.•The period 2007-2011 is the critical phase of decrease in sardine body condition.•Changes in temperature and chlorophyll-a may explain the decrease in body condition.•High levels of Chl-a during the critical phase suggest more complex trohic responses.