Sakas clarifies whale info
Thank you for printing the article about North Atlantic Right Whales in one of February’s weekly issues. The reporter, Sabrina Manganella Simmons, did an excellent job of presenting pertinent information on the issue of reducing ship speeds in and out of ports in an effort to eliminate ship strikes. I also appreciate the additional information provided by Mr. Michael Frick in a subsequent letter to the editor.
I do however want to explain further some of the statements I made. One of the statements that Mr. Frick contradicted was about our relatively shallow waters protecting our visiting North Atlantic Right Whales from sharks. In the past few years we have seen many more large sharks and in particular white sharks in our coastal waters. This past winter a large white shark was photographed feeding on a dead sub adult North Atlantic Right Whale.
So it is certainly likely that during the birthing of a calf, sharks would be attracted to the area; although we don’t know that for certain since to my knowledge the only North Atlantic Right Whale birth actually observed was by an aerial survey team in 2005.
During that observation the water was murky, as is typical of our coastal waters, and the sea state was choppy, making it difficult to see what else may have been in the water. The observers, however, reported no sharks present.
The statement that our relatively shallow offshore waters may serve as protection from large shark attacks has been suggested by some whale researchers. The reasoning is that shallow water (our coastal waters range in depth from a few feet adjacent to the beaches to 70 feet 20 miles offshore) offers little room for large sharks (a 20-foot white shark was photographed last year by a recreational boater) to gain much room for an attack from below since an adult whale is approximately 12 feet on a straight line from dorsal to ventral surface, or from back to stomach.
Often these whales will float a few feet below the surface. The observed birthing event took place in approximately 50 feet of water. With a whale taking up the first 15 feet or so of water from the surface in 50 feet of water, a 20-foot shark would have about 20 feet of water in which to stage an attack.
So it stands to reason that a large shark would have a harder time making an attack from underneath. At least one angle of attack would be relatively protected. While this theory has not been substantiated, it is nonetheless a plausible possibility and one theory expressed by some whale researchers.
The relatively warm winter water temperatures, however, remain the best supported reason for the choice of our coastal Georgia and northeast Florida waters by pregnant females as their calving grounds.
Another whale researcher commented to me about the statement I made concerning the minimal amount of blubber on calves. During necropsies he had conducted, he did find up to 30mm of blubber. His necropsies however were on older calves.
My statement was based on data I collected from a calf that was wither stillborn or live-born but had not nursed. That calf had no discernable blubber. It was determined that it had never nursed since there was nothing in the stomach and only meconium present in the intestines, which indicated it had received nutrients only through the placenta.
When calves are newborn they gain weight at an amazingly rapid rate for the first week and a half or so. That rate has been estimated to be upwards of 200 pounds per day! North Atlantic Right Whale milk ranks among the highest fat content for mammalian milk and has been reported to have the consistency of whipping cream.
Observers can tell when calves are nursing from the slick that appears on the water’s surface, apparently from milk leaking from the calf’s mouth and perhaps even from the mother herself.
Those whales are engaging and I am delighted that they generate such great interest. In response to the article, I have received many inquiries as to how people can watch them in our area. It is important for us all to appreciate that calving is the most critical time in a whale’s life and we must do all we can to protect them during this period.
To that end, a federal regulation requires that all boats and ships stay at least 500 yards from these whales. The less pressure a female receives the better able she will be to birth and nurture her calf, so one day it too will be able to make its contribution to the species and local population.
It is incumbent upon all of us to obey the laws that help ensure their safety and ultimately their survival. Besides, whale watching is very active off the New England coast and is best in summer.
Let’s keep our whales healthy and happy by not pressuring them with our desire to see them up close while they are trying to do the best job they can in birthing and nurturing their calves while visiting our waters during the winter months.
I invite readers to visit the numerous websites on the Internet (specifically New England Aquarium and WhaleNet) devoted to North Atlantic Right Whales to learn more about our most interesting and endangered winter visitors.
Cathy J. Sakas
Biologist, Naturalist, Educator
Education Coordinator and Co-Manager
Gray’s Reef National Marine Sanctuary
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