#8 Keeping track of Injuries

On December 15th, during one of the few aerial surveys the teams in the southeast US have been able to fly this December (inclement weather has been a problem), observers with Wildlife Trust came across a group of 6 right whales in a SAG off the coast of Georgia. Tricia Naessig, the team leader, noticed one whale with two series of propeller cuts on its left flank (pictured below). She sent images along to the New England Aquarium so that we could both evaluate the severity of the cuts and also match the animal to the catalog to determine when it was last seen.

We have been able to match the animal to #3745, a three year old male. This animal was last seen on February 26, 2009 also in the southeast U.S. The propeller cuts do not appear to be fresh. There are orange cyamids in the wounds and some grey skin in the vicinity of the cuts. Both of these features would take at least a couple of weeks to appear so we have no idea when or where this animal may have been struck.

The nature of the cuts; the distance apart, the length, and the apparent depth, indicate this was not a big vessel. Although it is difficult to pinpoint a propeller diameter and associated vessel length with precision, especially when accurate measurements of the cuts are not possible, there are several studies that have been done to evaluate propeller cuts on marine mammals, especially manatees. Yet, in this case, the best I can do is give an impression of vessel size based on the size of cuts I have seen in the past on right whales from known vessel sizes and the studies done by others. My impression is that the whale was struck by a twin engine vessel resulting in the two series of cuts and that this vessel was perhaps 30-40 feet long. Although the cuts are not parallel to one another as we would expect, it may be that during the strike, the whale was flexed. Or perhaps the propeller shaft for one of the engines got bent during the strike.

Photo Credit: Wildlife Trust

Vessel strikes by recreational vessels continue to be a problem for right whales. Typically these boats are moving fast and do not see the whale if it is submerged. The whale can't always respond quickly enough to avoid these fast moving vessels. Although these strikes by smaller vessels are not typically fatal, these animals can succumb to infection or effects of stress even months or years down the road. Efforts to educate recreational vessel operators all along the eastern seaboard about operating prudently around whales, especially during right whale migration and in seasonal use areas, continue to be paramount.

subscribe