A recent research study has discovered that critically endangered North Atlantic right whales are engaging in surface feeding at night, which elevates their vulnerability to boat strikes. The study, recently published in the peer-reviewed journal PLOS One, highlights the occurrence of nighttime surface feeding among North Atlantic right whales, offering crucial insights to mitigate fatal collisions between these whales and vessels.
Jay Kirkham, the lead author of the study and a PhD student at Dalhousie University in Halifax, collaborated with the U.S.-based non-profit Ocean Alliance to track 23 right whales in the Shediac Valley, an underwater valley in the southern Gulf of St. Lawrence. During the summer, a segment of the North Atlantic right whale population, estimated at around 384 individuals, congregates in the Shediac Valley for feeding purposes.
The tagged whales were monitored to capture video footage and movement data, aiding in observing their feeding behavior during the day. Kirkham described the unique feeding mechanism of right whales, likening it to a parachute that slows them down, prompting them to increase tail movement to compensate.
Utilizing these observations, Kirkham developed a machine learning algorithm capable of identifying nighttime feeding behaviors of right whales when visual identification was not feasible. The data unveiled that whales feed at a depth similar to that of large vessels at night, heightening the collision risk.
While right whales typically feed near the sea floor during the day, they shift their feeding activity higher in the water column at night to pursue zooplankton. Kirkham emphasized the vertical overlap between whales and ship traffic, underlining the dangers posed by potential collisions and entanglements in fishing gear, which are major causes of death among the population.
Current protection measures for the North Atlantic right whales are overseen by Transport Canada and Fisheries and Oceans Canada, focusing on preventing entanglements in fishing gear and enforcing seasonal fishing closures. Transport Canada enforces speed restrictions and a vessel exclusion zone in the Shediac Valley during the summer to minimize the risk of boat collisions with right whales.
Despite these measures, Kirkham noted that the tagged whales spent a significant portion of their feeding time outside the exclusion zone, exposing them to ship traffic. Transport Canada emphasized its whale surveillance program utilizing visual and audio detection tools to safeguard whales from collisions, leveraging scientific research and stakeholder feedback to enhance protective measures.
