Fig. 2: Sample locations and details for Atlantic bluefun tuna.

Fish capture locations (A) and otolith sampling regions (B) for Atlantic bluefin tuna. Colour gradient in (A) indicates mean annual sea surface temperature in 2021 obtained from the European Copernicus Marine Environment Monitoring Service104. White circles indicate capture locations, striped areas are known or probable spawning and juvenile nursery regions. Tuna sampled as age 0 or yearling fish were sampled within the Gulf or Mexico or Mediterranean Sea. Tuna were sampled at all life stages within the Mediterranean Sea (full details in supplementary data). Map Source: QGIS 3.38.3 TM_WORLD_BORDERS_SIMPL-0.3. B shows a whole otolith (top) and section indicating the portion milled representing the first year (middle) or the first 3 months (bottom) of life.