Figure 1

Maps of the study area showing the (a) bathymetry and the contrasted light cycles in (b) July and (c) December with all the associated locations recorded from the 17 satellite tracked harbour porpoises (black dots). The tagging site (Maniitsoq) is indicated by a red dot in each panel and the blue dashed line refers to the Arctic circle. In (b,c), the color-coded polygons refer to the light regimes based on solar elevation on July 15 and Dec 15 at sunset in Maniitsoq city: day (angle > 0°), twilight (between 0 and −18°) and night (< −18°). Mean daylength, sunrises and sunsets represent July 15 and December 15 at the porpoises’ locations.