are humpback whales in Ireland young males prospecting new feeding grounds?
Simon Berrow (1), Pádraig Whooley (1), Conor Ryan (2)
(1) Irish Whale and Dolphin Group (2) Galway-Mayo Institute of Technology simon.berrow@iwdg.ie
Humpback whales are frequently recorded in inshore Irish waters from July through to December. Since 2001, images of 17 individual humpback whales in Irish waters have been collected. Fourteen of these have been re-sighted within a year and eight re-sighted inter-annually, a rate of 47%. Some individuals have been recorded over a 3-4 month period within the same year suggesting that the habitat provides a good foraging area. Four individuals have been recorded over a three year period and one animal over seven years. Estimated length of humpback whales photographed in Ireland were less than 12m and none were considered to have reached adult size. From these 17 individuals, biopsy samples were collected from eight animals. Using molecular sexing all individuals sampled to date were determined to be male. We suggest that humpback whales that have been recorded inshore around the coast of Ireland are young, sexually immature males that are returning each year to good feeding grounds prior to attaining sexual maturity. Where these whales travel outside of Ireland to breed is still not known but we suggest that following attainment of sexual maturity, humpback whales may change their pattern of migration and do not return to these coastal feeding areas.