Fin whale localized acoustic detections off Kauai 2011-2017

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

Dataset credits:
Naval Information Warfare Center Pacific

Abstract:
Male fin whales sing by producing 20-Hz pulses in regular patterns of inter-
note intervals. While singing, fin whales may also alternate the frequency
ranges of their notes. Different song patterns have been observed in
different regions of the world's oceans. New song patterns suddenly
emerging in an area have been hypothesized to either be indicators of new
groups of whales in the area or signs of cultural transmission between
groups. Since the status of fin whales around Hawaii is unknown and visual
surveys are expensive and difficult to conduct in offshore areas, passive
acoustic monitoring has been proposed as a way to monitor these whales.
We used passive acoustic recordings from an array of 14 hydrophones to
analyze the song patterns of 115 fin whale encounters made up of 50,034
unique notes off Kauai, Hawaii from 2011--2017. Fin whale singing patterns
were more complicated than previously described. Fin whales off Hawaii
sang in five different patterns made of two 20-Hz note types and both
singlet and doublet inter-note interval patterns. The inter-note intervals
present in their songs were 28/33 s for the lower frequency doublet, 30 s for
the lower frequency singlet, 17/24 s for the higher frequency doublet, 17 s
for the higher frequency singlet, and 12/20 s for the doublet that lternated
between both note types. Some of these song patterns were unique to
these fin whales in Hawaiian waters, while others were similar to song
patterns recorded from fin whales off the U.S. west coast. Individual fin
whales often utilized several different song patterns which suggests that
multiple song patterns are not necessarily indicators of different
individuals or groups. The dominant song pattern also changed over these
years. Cultural transmission may have occurred between fin whales in
Hawaiian waters and off the U.S. west coast, which has resulted in similar
songs being present at both locations but on lagged timescales.
Alternatively, groups occupying the Hawaiian waters could shift over time
resulting in different song patterns becoming dominant. This work has
implications for the population structure and behavior of Hawaii fin
whales.