Minkes on the Move

Dec 10, 2014

The elusive minke whale is a marine mammal that is shrouded in mystery. For a baleen whale it is relatively small and quick, and despite its territory being widespread, the species is seldom spotted in B.C.’s eastern North Pacific waters. When a minke is seen, it can be a challenge to track due to its tendency to surface unpredictably after long deep dives. As a result of these evasive maneuvers, there is much about this species that we do not know. But, thanks to a long standing photo identification study started in 2005 by the Marine Education and Research Society (MERS), in collaboration with many researchers based on the British Columbian and Washington coasts, an important piece of the minke puzzle has recently been solved (see full article here in the Journal of Cetacean Research and Management).

As efforts to photo-identify minke whales were undertaken, it became evident that most sightings were occurring between spring and autumn. These whales were simply not being spotted during the winter months. It was also noted that some minkes showed preferences to certain areas, as researchers photographed particular whales in the same locations as previous years.

Another critical observation derived over the course of this study was that some of these mammals were seen making long-range movements within a years’ time. It was recorded that some individuals moved up to 424km in a northern direction in the spring, and 398km in a southern direction in autumn, marking the furthest documented movements for this species in the Pacific Ocean!

In addition to studying minke whale movements, researchers also paid close attention to scars or barnacles, referred to as ecological markers, on particular individuals. Old scars were documented, as well as new scars that appeared each year. These peculiar markers were spotted on various whales sighted during the study and were of particular interest because it is very unlikely they were obtained in B.C. waters.

Some of the minkes had distinctive circular markings thought to be from cookiecutter sharks, a species which normally inhabits warmer waters than those found in the eastern North Pacific. No open or fresh scars were documented on minke whales in cold waters, indicating that these whales were acquiring scars during the winter in warmer waters.

Another peculiar finding was the presence of a barnacle called Xenobalanus globicipitis on certain minke whales. Like cookiecutter sharks, this barnacle species also inhabits in warmer waters. Sightings of minke whales with these ecological markers likely obtained in warmer waters provide evidence that those individuals probably spend a portion of their time in warmer waters, supporting the idea that minke whales can and will migrate.

It has been generally thought that these minkes embark on a seasonal migration to warmer waters in the winter, and colder waters in the summer. But, in some temperate areas, they have been spotted year round meaning some individuals could be considered to live locally all year. The clear seasonal movements documented in this study demonstrate that minkes found in the eastern North Pacific do indeed migrate to higher latitude colder waters during the summer, and lower latitude warmer waters during the winter. This valuable information marks a significant step in solving the minke puzzle as we work to better understand one of B.C.’s most fascinating and elusive cetacean species.

Researchers are always looking for more information on minke whales off B.C.’s coast. If you spot a minke, or any other whale, dolphin, or porpoise, make sure to report them to the B.C. Cetacean Sightings Network online here, via email (sightings@vanaqua.org) or through our toll-free number (1 866 I SAW ONE).

Reference

Towers, J. R., McMillan, C.J., Malleson, M., Hildering, J., Ford, J.K.B., & G. M. Ellis. 2013. Seasonal movements and ecological markers as evidence for migration of common minke whales photo-identified in the eastern North Pacific. J. Cetacean Res. Manage. 13(3): 221-229.

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