U.S. Department of Commerce


Date of this Version



Report prepared under Contract No. AB133F-08-SE-4534 (2009) 1-17


The impacts of mid-frequency active sonar on the behavior of individual cetaceans may vary depending on their history of prior exposure. Evidence from habitat use, repeated sightings of identified individuals, and satellite tagging all indicate the existence of resident populations of Cuvier’s and Blainville’s beaked whales off the island of Hawai‘i, within the Navy’s Hawai‘i Range Complex. The number of individuals that have been satellite tagged is small however, and we are combining additional satellite tagging with individual photo-identification studies to assess movements and residency of both species. Field efforts were undertaken off the island of Hawai‘i in December 2008 and April and May 2009 to examine movements and habitat use. We obtained additional movement information from one satellite tagged Cuvier’s beaked whale (36 days) and one satellite tagged Blainville’s beaked whale (40 days). The Cuvier’s beaked whale had been previously photo-identified in three different years and was linked by association with other whales from the island-associated population including three individuals satellite tagged in 2007 and 2008. During the 36 days of signal contact the whale remained strongly associated with the island, but spent the majority of its time off the east (windward) side of the island, providing the first evidence that individuals from the resident island-associated population use the windward side of the island. The tagged Blainville’s beaked whale and the other two individuals in the group had not been previously photo-identified, and were encountered further offshore (31.3 km) and in deeper water (3,500 m) than had been documented for the island-associated population. During the first day after tagging the whale approached closer to shore, then reversed course and traveled approximately 900 km westward for 19 days at a median rate of horizontal movements of 2.41 km h-1. The whale spent the last 20 days utilizing a broad area over 4,000 m deep located 900 to 1,000 km from the tagging location. The average depth used over the 40 days (median = 4,702 m) was more than three times greater than that recorded from eight previously satellite tagged Blainville’s beaked whales from the island-associated population. The lack of associations, deep-water habitat use, and movement patterns, all suggest this individual is from an open-ocean population of Blainville’s beaked whale, evidence that there may be at least two stocks of this species within the Hawaiian Exclusive Economic Zone. Genetic studies to confirm this are needed. These results also illustrate the importance of individual photoidentification to interpreting the movement patterns of individual beaked whales and potentially their responses to mid-frequency active sonar.