Short-term movements of long-finned pilot whales Globicephala melas around the Faroe Islands

On 15 July 2000, a pod of about 80 long-finned pilot whales Globicephala melas was driven to the coast at Sandavágur, the Faroe Islands (62.055°N, 7.157°W) for the purpose of tagging selected whales with satellite-linked radio transmitters. A transmitter was attached to the anterior flank of the dorsal fin of four beached whales. After the tagging, all four whales were reunited with their pod and the entire pod was driven to sea. The positions of three of the four whales were tracked (one for a period of 47 days) and the results show that the whales separated after a few days and eventually went in different directions. After 10 days, two of the whales were observed together in a pod, and after 19 days two of the whales were located at positions determined to be within 2.3 km of each other. The whales showed a strong affinity for the deep water off the continental shelf. The sex and relatedness of the four, tagged whales were determined from skin biopsies. The tagged whales comprised one adult female with one juvenile in puberty, possibly her male offspring, and two adult males, one of which could be the offspring or the sibling of the female. The swimming speed of the whales was estimated at 0.2–14.5 km/hour, and they travelled average distances of 70–111 km/24 hours with a maximum of 200 km in 24 hours. Considering the mobility of the whales, it seems likely that the catches that occur at the Faroe Islands are recruited from a larger area in the North Atlantic than previously presumed. This suggests that the whales are taken from a larger population than that estimated from coastal areas around the Faroe Islands, hence increasing the probability that the harvest is sustainable.