North Atlantic right whale shift to the Gulf of St. Lawrence in 2015, revealed by long-term passive acoustics

Abstract

This paper contributes to documenting a change in the distribution of North Atlantic right whales Eubalaena glacialis (NARWs) that occurred in the 2010s, when the whales largely abandoned their traditional summering grounds in the Gulf of Maine/Bay of Fundy/Scotian shelf. Data from a year-round passive acoustic monitoring (PAM) network in the Gulf of St. Lawrence were exploited to build the time series of NARW incursions into this inland sea of the Northwest Atlantic, from June 2010 to November 2018. NARWs visited the southern Gulf of St. Lawrence every year from June to January, until ice freeze-up. The earliest detections were made at the end of April and the latest in mid-January. Call occurrence peaked between August and the end of October. NARW contact calls were not detected at the most upstream station at Les Escoumins, in the Lower St. Lawrence estuary, or at the northeastern connection of Belle Isle Strait with the Atlantic, which was monitored from November 2010 to November 2011. The mean daily occurrence of NARWs in the feeding grounds off Gasp quadrupled after 2015 compared to 2011-2014. Long-term continuous PAM data provided invaluable information to document this marine mammal distribution shift.