Bryde's whale localized acoustic detections off Kauai 2013-2022

Original provider:
Regina A. Guazzo, Naval Information Warfare Center Pacific

Dataset credits:
Naval Information Warfare Center Pacific

Abstract:
A unique acoustic call was identified and attributed to the Bryde’s whale in
the central North Pacific in 2015, but little is known about the distribution,
calling behavior, or swimming behavior of Bryde’s whales in the region.
Acoustic detections attributed to Bryde’s whales were used to localize and
track individual whales on the U.S. Pacific Missile Range Facility (PMRF) in
Kaua‘i, Hawai‘i. This study included 150 acoustically derived tracks from
recordings spanning the years 2011–2022 with recording effort in nearly
every month. Bryde’s whale movement was examined relative to calendar
year, day of year, hour of day, wind speed, and acoustic calling rate. Hidden
Markov models were used to identify two kinematic states (slower, less
directional movement and faster, more directional movement). The
findings indicate that Bryde’s whales were more likely to travel in a faster
and more directional state during the daytime than at night and between
May and August when compared to other times of year. The along-track
acoustic cue rate was examined for 118 tracks, and the findings indicate a
possible lengthening of the median inter-call interval over the duration of
the study period. These results are an important first step in understanding
more about behavior in Bryde’s whales, a relatively understudied species.