Figure 1. Characterization of the study area by (A) average annual temperature (°C) and (B) log-transformed chlorophyll a concentration (mg m⁻³).

The dark line represents the general limit of southern species established by Forbes [55], and the dark circles correspond to the P. maximus populations sampled from (1) Vigo, (2) Ile de Re, (3) Bay of Brest, (4) Bay of Seine, (5) Plymouth, (6) Holyhead, (7) Scarborough, (8) Campbell Town, (9) Austevoll, (10) Bessaker, (11) Bronnoysund, and (12) Traena.