Listening for minke whales: investigating [i]Balaenoptera acutorostrata[/i]'s spatiotemporal distribution in the Caribbean region and Gulf of Mexico, using passive acoustics

Abstract

Balaenoptera acutorostrata, one of the smallest baleen whales, is challenging to observe due to its relatively small size and poor surface behavior. Consequently, gaps remain in our understanding of its distribution, particularly in certain regions. The subspecies B. a. acutorostrata occurs in the North Atlantic, where migratory patterns have been documented. However, limited information is available regarding its winter distribution on the southern part of this range. To address this knowledge gap, a low-frequency (< 1 kHz) pulse train detector was applied to previously collected passive acoustic data from the Caribbean Sea and the southeastern coast of the United States to detect B. a. acutorostrata. The results revealed the presence of individuals in the area from November to May, confirming their use of the region as a wintering ground. Additionally, summer detections in Bermuda, the U.S. Virgin Islands, and Martinique suggest that some individuals may remain in the area year-round. Modeling of minke whales’ detections identified day of year and deployment depth as the most influential parameters. These results provide new insights into the distribution of B. a. acutorostrata in an understudied region although further research is needed to confirm specific migration routes.