A recent research study has discovered that the critically endangered North Atlantic right whales are now engaging in surface feeding at night, a behavior that puts them at a higher risk of being struck by boats.
The study, recently published in the peer-reviewed journal PLOS One, highlights the new findings on nighttime surface feeding in North Atlantic right whales. The research was conducted by a team led by Jay Kirkham, a PhD student at Dalhousie University in Halifax, in collaboration with the U.S.-based non-profit Ocean Alliance. The team tagged 23 right whales in the Shediac Valley, an underwater valley in the southern Gulf of St. Lawrence, where a portion of the North Atlantic right whale population, estimated to be around 384 whales, congregates for feeding during the summer.
The tags attached to the whales recorded video footage and data on their movements and swimming directions. Kirkham utilized the video footage to observe the whales’ feeding behavior during daytime. He described how the whales slow down when they open their mouths to feed on zooplankton, forcing them to exert more effort by increasing their tail movement.
To address the challenge of identifying nighttime feeding behavior, Kirkham employed machine learning algorithms trained on the observations gathered. The data revealed that the whales feed at a similar depth as large vessels at night, heightening the risk of collisions.
While North Atlantic right whales typically feed near the sea floor during the day, they follow their prey, zooplankton, higher in the water column at night. Kirkham explained the potential vertical overlap between the whales and large ships passing through the gulf, emphasizing the increased collision risk.
Collisions with vessels and entanglements in fishing gear are the primary causes of mortality in the North Atlantic right whale population. This study aims to provide valuable insights for implementing conservation measures to protect the whales.
Fisheries and Oceans Canada highlighted that their current measures focus on preventing entanglements and enforcing seasonal fishing closures. Transport Canada enforces speed restrictions and a vessel exclusion zone in the Shediac Valley during the summer to mitigate collision risks. However, Kirkham noted that tagged whales spent a significant portion of their feeding time outside the exclusion zone, exposing them to ship traffic.
Transport Canada mentioned its surveillance program utilizing visual and audio detection tools to safeguard the whales from collisions. The department emphasized the use of scientific research, monitoring data, and stakeholder feedback to inform protective measures for the whales.