A recent rapid increase in the number of Antarctic fur seals on Signy Island has caused extensive changes to terrestrial and freshwater ecosystems. A palaeolimnological study was carried out to determine whether the recent increase in the number of visiting fur seals has exceeded the range of natural variability of past populations and if a management response should be considered. Seal hairs in lake sediments from Sombre Lake were assessed as indicators of visiting fur seals. Results showed that sediments could be used to detect the presence, absence and possibly broad scale changes in the abundance of fur seals and indicated that fur seals have visited the island from the beginning of the sedimentary record (6570 ± 60 14C years B.P.) when the coastline became ice-free. However, the previous maximum number of seals visiting the study site appears to have been no more than a quarter of the number recorded in 1994. The timing of changes in fur seal hair abundance indicates that historical activities of the sealing and whaling industries may be partly responsible for the current increase in fur seal populations. The results of this study have provided a unique historical perspective from which appropriate conservation measures at Signy Island, and possibly at other sites on northern maritime Antarctic islands and on the west coast of the Antarctic Peninsula, can be considered to address and minimise the impact of the Antarctic fur seals.