On April 20 a NOAA marine mammal aerial survey team based at the Northeast Fisheries Science Center’s laboratory in Woods Hole, Mass., sighted nearly 100 endangered North Atlantic right whales feeding in Rhode Island Sound. This is the largest group ever to be documented in these waters.
“It all started with a flukeprint,” said Pete Duley, whale researcher at NOAA’s Northeast Fisheries Science Center who was on the team that spotted the whales.
A “flukeprint” is the whale equivalent of a footprint. It is visible on the surface of the water right before a whale dives when it is just underwater. The whale flexes its tail, or fluke, upward to help propel itself deeper. This movement creates a smooth patch on the surface that looks similar to an oil slick.
“We circled over the fluke print and found not one, but 38 feeding right whales, the largest group we saw all day,” said Duley. It only got better. “We expected to spend a couple of hours and perhaps see an animal or two,” said Allison Glass, another NOAA whale researcher that was part of the team. “Instead, we flew for 6 hours and counted 98, including a mother- calf pair.”
All of the whales were actively surface feeding, indicating dense patches of copepods, the zooplankton on which right whales feed. During this time of year the right whales migrate through southern New England waters generally headed northward to feed at different times and places throughout the summer.
North Atlantic right whales are particularly susceptible to boat collisions which often results serious injury or death. The likelihood of collisions is reduced when vessel speeds are slowed. The whales were sighted both within and just outside of waters that are also part of a seasonal management area for large whales intended to reduce the risk of harmful collisions. Within the area, vessels 65 ft or larger are required to abide by a speed limit of 10 knots or less between November 1 and April 30. NOAA has extended protection in adjacent areas by implementing a short-term management area that mariners are expected, but not required, toeither avoid or to voluntarily reduce speeds to 10 knots or less while transiting.
Another source of human-caused injuries and deaths among large whales is entanglement in some kinds of fishing gear. Pot /trap and gillnet fishermen throughout the northeast are required to rig their gear to make it less likely to injure or kill a whale that encounters it, and to mark gear to help identify any entangling line or gear that is recovered from an entangled animal.
NOAA’s Northeast marine mammal aerial survey team completes hundreds of survey flight hours annually over the waters off the northeast. This week’s aggregation rivals that documented in December 2008, when the team spotted 44 right whales in Jordan Basin in the central Gulf of Maine where they expected to see no more than a few.
Copyright © 2010 by Marine Science Today, a publication of OceanLines LLC