Our long-term study on top predator (seabirds and marine mammals) distribution in polar marine ecosystems aims at detecting possible temporal and spatial population changes, especially in the context of global changes in temperature and ice cover. Quantitative data on the seabird distribution were collected in the northern Greenland Sea and Fram Strait onboard the icebreaker RV Polarstern between 1988 and 2014, applying 30-min transect counts from the bridge, without width limitation (n = 7320). A drastic decrease in numbers by a factor of seven was detected for the ivory gull Pagophila eburnea from 2007 on. These data confirm the decrease of ivory gull previously detected in North Canada and North Greenland, leading to the conclusion that the species is “endangered” or “near threatened”. These changes are discussed in relation to the decreasing Arctic pack ice coverage leading to the opening of the Northwest and Northeast Passages in 2007, at the time the year with the lowest ice coverage ever recorded. On the other hand, the decrease was even stronger for Ross’s gull Rhodostethia rosea after 1993, apparently reflecting changes in migratory habits. The third high Arctic gull, Sabine’s gull Xema sabini, was only tallied in very low numbers, without any clear temporal evolution in numbers. |
