FOCUS
Whale calf death highlights rehab needs
By Louis M. Herman and Adam A. Pack
In more than one month, from February to March of this year, four humpback whale calves have died in Maui waters. Three were apparently abandoned, and the fourth died under its mother's care.
In three of the cases, tiger sharks were observed near the calves at their end, and in the last case, observed to actively attack, kill and eat the calf.
At least one of the calves appeared healthy and robust on its initial sighting. This calf was first observed Feb. 28 offshore of Ka'anapali by a whale-watch boat, and later that day by researchers from the Hawaii Whale Research Foundation headed by Dr. Dan Salden. The calf appeared well nourished.
It was seen again March 12 and 13 near Olowalu by researchers from the Kewalo Basin Marine Mammal Laboratory. At that time, the calf appeared thin, with many scratches and bruises. Earlier on the 12th, the calf had been observed within a competitive group of at least 10 whales by Dan Salden.
The researchers then followed the calf for the remainder of the day and observed it attempting unsuccessfully to affiliate with a variety of other whales. This included an escort whale that had left the competitive group and, sometime later, a lone singer that was stationary at about the 90-foot depth. As the singer changed its location, the calf followed. When the singer finally departed, the calf swam aimlessly about until dark.
The next day, researchers observed the calf once again at roughly the same location and remained with it throughout the day. During this time, the calf interleaved periods of traveling with periods of listlessness. Occasionally, the calf would circle the researchers' boat or rest its head under the boat, a behavior similar to that directed by calves towards their mothers.
At about 4:30 p.m., a large tiger shark was sighted near the calf. From then on, the calf hovered very close to the boat while the shark milled about behind it. This continued until dark. The calf was never seen again.
Comparisons of videotape records verified that the calf on February 28 was the same one seen March 12 and 13. The fact that the calf had survived on its own without food for almost two weeks suggests that it might have been saved if rehabilitation facilities had been available.
We are concerned about the lack of resources in Hawai'i for dealing adequately with these distressed calves. Hawai'i desperately needs a location with extensive facilities where whales or dolphins in distress can be brought and rehabilitated, rather then simply allowed to perish.
Successful rehabilitation of two gray whale calves has been accomplished in San Diego at the Sea World facility. The calves, Gigi and JJ, were successfully reared for a year and then returned to the wild during the gray whales' northward migration. Both calves were seen in subsequent years, providing evidence for successful rehabilitation. During the year that these calves were being nurtured, much was learned about their biology and behavior that could not otherwise be learned.
For humanitarian reasons alone, saving and rehabilitating a humpback whale calf would be a laudable goal, but, additionally, what may be learned about the biology and behavior of this endangered species can be of immeasurable value.
We have no sure explanation for the spate of calf mortalities observed this winter. It seems likely, however, that we can expect more of the same in subsequent seasons. It is time to act to bring about the needed legislation, resources and dedicated personnel to provide for the proper response and aid to distressed, stranded, or entangled whales.
Louis M. Herman, Ph.D. and Adam A. Pack, Ph.D. are director and assistant director of the Kewalo Basin Marine Mammal Laboratory (KBMML) of the University of Hawaii, and president and vice president of The Dolphin Institute.
