American Cetacean Society
Learning From Whales - Nov. 2004 Poster Presentations

2004 conference poster courtesy of Uko Gorter © 2004

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This Poster Presentation won 3rd Prize in the 2004 Student Poster Contest.

The following is an excerpt from the November 2004 conference program

HABITAT PREFERENCES IN HUMPBACK WHALE MOTHER AND CALF PAIRS IN NURSERY WATERS

Rachel Cartwright and Matthew Sullivan

The waters of the Hawaiian islands provide a winter time habitat for over 60% of the Central North Pacific stock of humpback whales. Between December and March humpback whales congregate in the inshore waters around the main islands, within the 100 fathom isobar. Historically most mother and calf pairs have favored the Four Island region and the Penguin Banks, more recently increasing numbers are also being seen along the North West coastline of the Big Island. Over the course of a five year study we monitored a total of 243 mother - calf groups in this region, including 49 groups along the North-west coastline of the Big Island and 196 groups in the Four Island area. Data recorded for each group included GPS location, group composition, fluke identification, calf body morphology and a 60 minute behavioral sample. Amongst the results obtained we determined that depth preference between the two areas was consistent. Overall distribution showed a clear avoidance of deep water in both regions and we provide suggestions on why these pairs may so clearly avoid deep water. Data on distance from shore indicated that in the Four island region mother and calf pairs use the extent of the shallow inter-island channels between Maui and Lanai. Management of this area as a nursery habitat therefore needs to extend across this region. On the North Kona-Kohala coastline, where coastline gradients are much steeper, mother and calf pairs showed a clear preference for inshore waters. Behavioral results indicated that Four Island calves spent far less time at the surface compared to Big Island calves. This may be a behavioral adaptation in response to high levels of boat traffic in this region and is of particular importance as the winter-time ban on parasailing in this area has just been lifted.

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