Connectivity and population structure in Pleuragramma antarcticum

We used stable isotope and trace element chemistry from otoliths to test whether silverfish (Pleuragramma antarcticum) are distributed in independent, discrete populations in the Ross Sea, over the West Antarctic Peninsula, and around the South Orkneys; or whether the Southern Ocean circulation leads to connectivity. Otolith chemistry showed strong heterogeneity indicating four separate populations: i) in the Ross Sea, ii) on the southern Antarctic Peninsula in Marguerite Bay and off Charcot Island, iii) off Joinville Island, and iv) around the South Orkney Islands. This suggested that silverfish are not transported by the Antarctic Circumpolar Current, shelf processes on the West Antarctic Peninsula, or along the Weddell Front. However, the otolith chemistry combined with particle simulations suggested fish from Marguerite Bay may be advected along the southern Peninsula to Charcot Island by the Antarctic Coastal Current.