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Leviathans of the Sea
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20295 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
7 / 1992 |
1,419 Words |
| Author
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Howard C. Rosenbaum
Howard C. Rosenbaum is a research associate in population
studies with the Center for Coastal Studies in Provincetown,
Massachusetts. As a 1990-91 Thomas J. Watson Fellow, he
conducted research on regional differences in tail
pigmentation of humpback whales found in the waters of the
United States, Australia, Mexico, Japan, and Colombia. |
A humpback whale breaks the surface of the water surrounding the Dampier Archipelago off the northwestern coast of Western Australia. As the whale arches its back and lifts its tail out of the water for a deeper submersion, a research team maneuvers its boat behind the animal. This enables them to shoot a series of photographs of the distinctive pigmentation patterns on the underside of the whale's tail. Individual humpback whales possess an array of black and white spots on their tails that are analogous to the fingerprint of a human. On the basis of these distinctive patterns scientists have identified thousands of individual humpback whales photographically, enabling further study and insight into the biology and behavior of this endangered species.
These leviathans of the sea do not spend their lives in one ocean basin. During the summer months, humpback whales feed in segregated regions of colder, nutrient-rich waters in both hemispheres. Then they undertake the longest migration of any known mammal to subtropical or tropical waters where individuals from a given ocean population congregate for mating and calving during the winter months. Upon completion of the breeding and calving season, these whales reverse their course of migration and return to their respective feeding regions in colder waters.
For example, in the North Atlantic, during the summer months, individual feeding "stocks" of humpback whales (reproductively isolated subpopulations) have been identified in the Gulf of Maine, Gulf of St. Lawrence, off the coasts of Newfoundland/Labrador, Greenland, and Iceland. Animals from one given region do not intermix with those from other regions during the feeding season. In October, these animals usually begin their migration to the warmer waters of the Caribbean surrounding the Dominican Republic and Puerto Rico. Whales from different northern feeding regions have been seen to occupy the same breeding regions and have been photographed in the same competitive groups. To complete the cycle, whales return to their respective breeding regions with newborn calves returning to the mother's feeding region.
Feeding time in the ocean
Humpback whale behavior varies greatly during the feeding and breeding seasons. During the feeding season, these whales can be seen traveling solo or in groups known as pods. The most spectacular behavior to witness during this season is the actual process of feeding. In the North Atlantic, humpback whales typically feed on small schooling fish such as sandlance, herring, and capelin. Whales
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