Cetaceans Surveyed in Main Hawaiian Islands

In recent years, the Pacific Islands Fisheries Science Center has expanded the scope of its research on protected species to include cetacean populations in the Pacific Islands Region. The Cetacean Research Program (CRP) engages in a wide range of scientific activities: visual and acoustic line transect surveys to measure cetacean distribution and abundance; photo-identification research to ascertain cetacean movements, stock structure, and habitat use; passive acoustic monitoring; habitat modeling; ecosystem studies; and more.

In February, 2009, the CRP led a line-transect visual and acoustic survey for cetaceans in the waters surrounding the main Hawaiian Islands. Observers searched for cetaceans along transect lines in the inner region of the Exclusive Economic Zone (EEZ) surrounding the islands, the same transect lines used in 2002 during the Hawaiian Islands Cetacean and Ecosystem Assessment Survey. Replication of the previous search path provides an opportunity to compare the distribution and abundance of cetaceans within this insular region.

Observers visually surveyed over 1250 nmi of trackline, resulting in 116 sightings of 13 identified cetacean species. They collected 5 biopsy samples and numerous identification photographs of individual cetaceans. Sighting data are currently being analyzed to provide updated estimates of cetacean abundance and density in the inner-EEZ region, including updated estimates for false killer whales. This species is of particular interest as it is the marine mammal most commonly observed to interact with the Hawaii-based pelagic longline fishery.