The study area off Maui is surveyed each year from the second week of January through the end of April. Surveys are conducted 6 days a week for an average of 8 hours per day. The primary study area was between 20° 47´ N. Latitude and 21°12´ N. Latitude and 156° 33´ W. Longitude and 157° 0´ W. Longitude.

Upon sighting whales, our research vessel closes to within 100 m of the group, assuming a placement behind the whale group for purposes of obtaining fluke identification photographs. Once the whales are identified, behavioral data are recorded. For each encounter, the following information is maintained in a written field log: (1) encounter start and end times, (2) encounter start and end positions (using a handheld GPS device), (3) number of humpbacks (including counts of both adults and calves), (4) a behavior classification for the encounter, (5) summaries of identification and behavior photographs taken during the encounter, and (6) a narrative summary of behavioral interactions. Identifications and behavioral interactions are documented using still photography, which is supplemented by digital surface and underwater videography. These data are entered into a computer database each evening for subsequent analysis. In addition to the written field log, supplementary audiocassette narratives of behavior and photo documentation are produced for each encounter.

Humpback identifications are based on photographs of the pigmentation pattern on the ventral surface of the flukes, as described by Katona et al. (1979).