NARRAGANSETT — A greater understanding of whale behavior has been instrumental in reducing the number of ship strikes and fishing gear entanglements in the Stellwagen Bank National Marine Sanctuary.
In a Feb. 13 presentation at the University of Rhode Island’s Graduate School of Oceanography, Stellwagen research coordinator David Wiley described research projects that are yielding valuable data on humpback whale feeding behavior. That information has in turn resulted in the shifting of shipping lanes and the modification of fishing gear.
Located off the coast of Massachusetts, the Stellwagen Bank sanctuary, which is managed by the National Oceanic and Atmospheric Administration, comprises more than 800 square miles. Wiley has been studying the baleen whales in the sanctuary since 2001, trying to find ways to protect them in nutrient-rich waters that attract the animals but are also heavily used by ships and commercial fishermen.
“I’m a conservation biologist, so I want to know what the problems are and try to solve those problems, and some of the biggest problems are getting entangled in fishing gear and hit by boats,” he said.
In addition to being a conservation issue, particularly in the case of the critically endangered right whale, entanglement is an animal welfare issue because of the prolonged suffering it causes. Using a map of the sanctuary, Wiley pointed to clusters of dots that indicated where whales had been either been struck by ships or gotten tangled in gill nets or lobster fishing gear.
“We’re one of the most heavily fished areas in New England,” he said. "Kind of odd for a marine sanctuary … The co-occurrence of whales and fishing gear has a tendency to whales becoming entangled in fishing gear.”
While some feeding behaviors such as bubble netting, in which whales work together to produce bubbles that corral fish, are easily visible at the surface, other behaviors have, until recently, been poorly understood.
Researchers are now able to document whale feeding using tags, some equipped with video cameras, that temporarily attach to the whales’ skin with suction cups. The tags drop off the whales after about 40 hours.
“Almost all of them have pitch, roll and heading and depth, so you can kind of make a map of what the animals are doing,” Wiley said. “Some of them have video cameras built into them and some of them have really great acoustics built into them. So, we can look at lots of different things.”
The swim patterns of humpback whales are entered into a software program which creates a three-dimensional rendering of their activities in startling detail.
“These are the animals on the surface,” Wiley said, pointing to a graphic. “You’ll see these little polygons coming up and down. Those are actually their fluke strokes. So every time the animal flukes up and down it’s retained in the tag record … Here, you can see the animals making a dive and you can see they just glide effortlessly down to the bottom.”
The tags also recorded another cooperative humpback whale behavior, hunting for small fish called sand lance that live in the sand of the ocean floor.
Data from two tagged whales showed that they were hunting sand lance together.
“The animals were diving down together and when they got down to the bottom, they were going head to head with each other,” Wiley said.
Rolling on their sides, the whales come at the sand lance from different directions, corralling the fish and making them easier to catch.
Whales never remain in one place for long. In a single 24-hour period, they use the entire water column, from the surface to the ocean floor.
“There are different things in the water column that can bother a whale,” Wiley said. “One is fishing gear — they set them on the bottom, but also these lines running from the top to the bottom.”
Wiley and other concerned scientists have proposed moving shipping lanes away from areas of Stellwagen Bank where the ocean bottom is sandy, because that’s where humpback whales hunt for sand lance. He has also worked with commercial fishermen to develop modifications that make fishing gear less hazardous to whales.
In 2009, Wiley was awarded a Gold Medal by the Secretary of Commerce for his leadership of research projects to protect endangered whales in and around the sanctuary.
Wiley has found that whales are always vulnerable to fishing gear and are at risk of being hit by ships about half the time. Understanding what humpbacks are doing throughout the day and night has led Wiley to conclude that reducing risk to whales involves reducing human activities in the vicinity of the whales.
“Their life depends on them being in those particular parts of the water column, so the only way we can reduce that risk is really by reducing the amount of human activity in those same areas, either reducing ship traffic and moving shipping lanes or showing ships down — that can help the mortality factors — or removing gear in the water, or removing the profile of the gear in the water,” he said.