A recent research study has discovered that critically endangered North Atlantic right whales are now feeding closer to the surface of the ocean at night, which increases their vulnerability to collisions with boats.
The study, recently published in the peer-reviewed journal PLOS One, has documented this nighttime surface feeding behavior in North Atlantic right whales. This new evidence could potentially be utilized to prevent fatal collisions between the whales and vessels.
The lead author of the study, Jay Kirkham, a PhD student at Dalhousie University in Halifax, collaborated with the U.S.-based non-profit Ocean Alliance to equip 23 right whales with tracking devices in the Shediac Valley, an underwater valley in the southern Gulf of St. Lawrence.
During the summer, a segment of the estimated 384 North Atlantic right whale population congregates in the Shediac Valley to feed. Kirkham explained that the tracking devices collected video footage and data on the whales’ movements and swimming directions.
Using the video footage, Kirkham observed the whales’ feeding behavior during the day and noted that when the whales feed, they slow down significantly due to their mouth acting like a large parachute, leading them to kick their tail harder to compensate.
Based on the gathered data, Kirkham developed a machine learning algorithm to identify nighttime feeding behavior when visual identification was not feasible. The results showed that the whales feed at similar depths to large vessels at night, heightening the risk of collisions.
While the whales typically feed near the sea floor in the daytime, they follow their food source, zooplankton, to higher locations in the water column at night. Kirkham highlighted that this behavior places them in a vertical overlap with passing ships.
Collisions with vessels and entanglements in fishing gear are the primary causes of mortality among the North Atlantic right whale population. The study aims to contribute valuable insights for conservation efforts to protect these whales.
Presently, protection measures for the North Atlantic right whale population are overseen by Transport Canada and Fisheries and Oceans Canada. Fisheries and Oceans Canada emphasized that the study findings can aid in tailoring management strategies to safeguard the whales.
Transport Canada enforces speed restrictions and maintains a vessel exclusion zone in the Shediac Valley during the summer to mitigate the risk of boat-whale collisions. However, Kirkham noted that a significant portion of the tagged whales spent a considerable amount of their feeding time outside this exclusion zone, exposing them to vessel traffic.
Transport Canada stated that they have a surveillance program dedicated to safeguarding right whales from collisions using visual and audio detection tools. They highlighted the importance of utilizing acoustic monitoring systems and other technologies to support whale detection and inform protective measures.
By leveraging the latest scientific research, monitoring data, and stakeholder feedback, Transport Canada aims to continually enhance its protection measures for the North Atlantic right whales.