Figure 1.

Sampling locations for herring in spawning condition and for herring in mixed feeding or overwintering aggregations. Spawning locations are numbered as in electronic supplementary material, table A1). For the MSA, locations 1–10, 11–13, and 14–18 were pooled into: region 1 (n=1332) comprising autumn (filled circle in orange), spring (filled circle in green) and winter (filled circle in red) spawners in the North Sea; region 2 (n=635), comprising spring spawners from the Skagerrak (plus), and region 3 (n=1010), comprising spring spawners (filled triangle in green) from the Kattegat and Western Baltic. The locations for the mixed aggregations are indicated by stars, solid stars (2002), open stars (2003): blue, summer feeding aggregations; red, overwintering aggregations, respectively. See electronic supplementary material for details.