The North Atlantic right whale is considered to be the most endangered large whale species, with a total population of less than 300 and a low reproductive rate. In addition, the species suffers a substantial number of fatalities each year due to collisions with ships.
The September 7 issue of The Royal Society Proceedings B Vol. 268, No. 1478, features an article on the right whale which seems to explain this animals' relatively frequent collisions with ships.
A team from Woods Hole Oceanographic Institution (WHOI) attached non-invasive recording devices to North Atlantic right whales in order to analyze their swimming/diving and acoustic behavior.
It was found that right whales, unlike other marine mammal species, were positively buoyant at near surface water depths, where others were negatively buoyant.
In contrast to other whale species, the right whale glides during the ascent portion of its dives instead of the descent, but they maintain a similar or greater ascent rate, which could only be achieved with the assistance of some buoyant force.
These results provide insight into how the natural behavior of this whale species may increase its risk of being hit by ships. Even if a right whale correctly perceives a ship as a threat, its ability to maneuver may be compromised by its buoyancy, leaving it vulnerable to ship strikes.
(Reference: Buoyant Balaenids: the ups and downs of buoyancy in right whales, by D. P. Nowacek, M. P. Johnson, P. L. Tyack, K. A. Shorter, W. A. McLellan, and D. Ann Pabst. The Royal Society Proceedings B Vol. 268, No. 1478 Pg 1811)
[Contact: Douglas P. Nowacek]
29-Aug-2001
