Satellite tracking of Bryde’s whales Balaenoptera edeni in the offshore western North Pacific in summer 2006 and 2008

Movements of two individual Bryde’s whales (Balaenoptera edeni) were recorded using satellite-monitored radio tags in the offshore western North Pacific where no such data had been recorded. One individual was recorded for 13 days 4 h 57 min from 13 to 26 July 2006. The total traveled distance of the individual was 917.3 km with a mean speed of 2.9 km/h. The other individual was recorded for 20 days 5 h 5 min from 24 July to 13 August 2008. The total traveled distance of the individual was 2649.7 km with a mean speed of 5.5 km/h. It has been documented that the subarctic-subtropical transition area (around 40°N) is one of the feeding areas of Bryde’s whales in summer. However, the results revealed that some individual Bryde’s whales moved from the subarctic-subtropical transition area to the subtropical area even in summer. The observation indicated Bryde’s whales did not stay in a feeding area persistently throughout summer. This study provides the first information regarding the continuous movement of Bryde’s whales in the offshore western North Pacific in summer which enhances understanding of their life history.