A recent research study discovered that critically endangered North Atlantic right whales are now choosing to feed closer to the water’s surface at night, which increases their vulnerability to collisions with boats. The findings, published in the peer-reviewed journal PLOS One, shed light on the nighttime feeding behavior of these whales and offer insights that could help mitigate deadly encounters between the whales and marine vessels.
Led by Jay Kirkham, a PhD student at Dalhousie University in Halifax, the study involved tagging 23 North Atlantic right whales in the Shediac Valley, located in the southern Gulf of St. Lawrence. This valley serves as a feeding ground for a portion of the estimated 384 North Atlantic right whale population during the summer months. The tags attached to the whales captured video footage and tracked their movements and swimming directions.
Kirkham utilized the video recordings to observe the feeding behaviors of the right whales during the daytime. He noted that when the whales feed, their mouth functions like a large parachute, slowing them down significantly. To compensate, the whales increase the intensity of their tail movements to maintain their feeding activity.
The study further employed machine learning algorithms trained on these observations to identify nighttime feeding behaviors of the whales. It revealed that the whales feed at similar depths as large vessels during the night, escalating the risk of collisions. While the whales typically feed near the sea floor in daylight hours, they follow their food source, zooplankton, to higher water levels at night.
Collisions with ships and entanglements in fishing gear are the primary causes of mortality among North Atlantic right whales. The study’s findings could help shape conservation strategies to safeguard these animals. Current protection measures overseen by Transport Canada and Fisheries and Oceans Canada focus on preventing entanglements in fishing gear and enforcing seasonal fishing closures.
Transport Canada, in collaboration with Fisheries and Oceans Canada, enforces speed restrictions and a vessel exclusion zone in the Shediac Valley during the summer to reduce the chances of boat-whale collisions. However, Kirkham highlighted that the tagged whales spent a significant portion of their feeding time outside the protected zone, exposing them to ship traffic.
Transport Canada mentioned its whale surveillance program, which employs visual and audio detection tools to enhance whale protection from collisions. By leveraging the latest scientific research and stakeholder feedback, the department aims to continually refine its protective measures for these endangered marine mammals.