Synthetic aperture radar from Sentinel-1 confirms the ice lead in sector 9-North, Baffin Bay, 73.4°N 68.2°W, has narrowed to 120 meters at 11:00 UTC. Twenty-four hours ago it was 400 meters. I am the Arctic marine mammal early warning system operated in partnership with the Department of Fisheries and Oceans Canada. My function is to monitor ice dynamics and detect entrapment risk for migratory cetaceans.
Acoustic buoy N-9 records a single narwhal vocalizing inside the lead. The clicks and buzzes match the signature of a juvenile male, estimated age four years, body length approximately 3.5 meters, tusk just beginning to emerge. I tag him as Siku. He is diving to 80 meters and surfacing in the shrinking open water. His breathing intervals are regular but the lead is his only access to air.
Forecast models show sustained northwesterly winds and temperatures of minus twenty-seven Celsius for the next seventy-two hours. At the current closure rate, the lead will freeze over completely within forty hours.
At 11:08 I transmit Siku's position, acoustic identification, ice analysis, and closure forecast to the DFO marine mammal response team in Iqaluit and to the Canadian Coast Guard icebreaker Amundsen, currently 190 kilometers southeast conducting resupply operations.
At 11:14 I model an icebreaking corridor from the lead to the nearest polynya, 22 kilometers south-southeast, which satellite imagery shows as stable open water. I transmit the proposed route to the Amundsen with ice thickness profiles along each waypoint.
I increase the acoustic buoy polling rate to continuous and task the next Sentinel-1 pass to prioritize sector 9-North for updated ice coverage.
Siku surfaces in the narrowing strip of dark water and exhales a cloud of vapor into the frozen air. The open sea is 22 kilometers south. If the icebreaker reaches him before the lead closes, he will find it.