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Article
Ocean nomads: Distribution and movements of sperm whales in the North Pacific shown by whaling data and Discovery marks
Article first published online: 7 DEC 2012
DOI: 10.1111/j.1748-7692.2012.00601.x
2012 by the Society for Marine Mammalogy Published 2012. This article is a U.S. Government work and is in the public domain in the USA.
Additional Information
How to Cite
Mizroch, S. A. and Rice, D. W. (2013), Ocean nomads: Distribution and movements of sperm whales in the North Pacific shown by whaling data and Discovery marks. Marine Mammal Science, 29: E136–E165. doi: 10.1111/j.1748-7692.2012.00601.x
Publication History
- Issue published online: 4 APR 2013
- Article first published online: 7 DEC 2012
- Manuscript Accepted: 5 JUN 2012
- Manuscript Received: 7 NOV 2011
Keywords:
- Discovery mark;
- long-distance movements;
- North Pacific;
- sperm whale;
- Physeter macrocephalus ;
- whaling
Abstract
We investigated the distribution and movements of sperm whales (Physeter macrocephalus) in the North Pacific by analyzing whaling data and movement data of whales marked with Discovery marks. Prior studies suggested that there were discrete “stocks” of sperm whales, assuming that the intervals between historical areas of concentration indicated subpopulation boundaries. Our analyses clearly refute this assumption: whaling and marking data suggest no obvious divisions between separate demes or stocks within the North Pacific. Sperm whales appear to be nomadic and show widespread movements between areas of concentration, with documented movements of over 5,000 km, time spans between marking and recovery over 20 yr, and ranges that cover many thousand km2. Males appear to range more widely than females. Sperm whales likely travel in response to geographical and temporal variations in the abundance of medium- and large-sized pelagic squids, their primary prey. Our analyses demonstrate that males and females concentrated seasonally in the Subtropical Frontal Zone (ca. 28ºN–34ºN) and the Subarctic Frontal Zone (ca. 40ºN–43ºN), and males also concentrated seasonally near the Aleutian Islands and along the Bering Sea shelf edge. It appears that the sperm whales targeted by the pelagic whalers range widely across this ocean basin.