A Blue Whale, the largest living mammal on earth, was sighted yesterday (17th September) from the RV Celtic Explorer by an observer from the Irish Whale and Dolphin Group who was accompanying a Marine Institute deepwater fisheries survey.
Dave Wall of IWDG was watching the waves from the specially constructed whale-watching platform above the Celtic Explorer’s bridge when he spotted a blue whale feeding in a series of shallow dives.
The sighting was made on the north slopes of the Porcupine Bank. The whale was observed feeding on marks at 50-120m. It dove on average for 10mins and surfaced 5 or 6 times between dives at intervals of 10-20 seconds.
Confirmation of the species was made when the animal fluked 3 times showing a thick uniform colour tail stock curving sharply to the massive flukes another key feature was the small dorsal fin (see third photo below by Graham Johnston, FEAS, Marine Institute).
The species identity was confirmed by experts in the United States. It is thought that the whale was feeding on euphausiid shrimp (krill). A number of similar whale blows were seen in the vicinity, raising the possibilty of more than one animal feeding in the area. During the eight days of the survey so far 72 sightings of at least seven different cetacean species have been recorded including the blue whale, 45 fin whales, 11 sperm whales and three beaked whales.
Images and text courtesy of Dave Wall and the Irish Whale and Dolphin Group