Singing fin whale swimming behavior in the Central North Pacific

• Published in: Frontiers in Marine Science
• Main Authors: Guazzo, Regina A., Durbach, Ian N., Helble, Tyler A., Alongi, Gabriela C., Martin, Cameron R., Martin, Stephen W., Henderson, E. Elizabeth
• Other Authors: University of St Andrews. Statistics, University of St Andrews. School of Mathematics and Statistics
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Marine Science; Fin whale (Balaenoptera physalus); Kinematics; Swimming speed; Inter-note interval; Passive acoustic monitoring; Song (or singing); Behavior; Marine ecology; GC Oceanography; QA Mathematics; QH301 Biology; DAS; SDG 14 - Life Below Water; GC; QA; QH301; Pacific; Balaenoptera physalus; Fin whale
• Online Access: http://hdl.handle.net/10023/24045; https://doi.org/10.3389/fmars.2021.696002

This research was supported by Commander, U.S. Pacific Fleet (Code N465JR, Award Number N0007020WR0EP8F), the Office of Naval Research (Code 322, Award Number N0001421WX00156), and tool development necessary for this analysis was supported by the U.S. Navy's Living Marine Resources Program (Award Number N0002520WR0141R). Male fin whales sing using 20 Hz pulses produced in regular patterns of inter-note intervals, but little is known about fin whale swimming behavior while they are singing. Even less is known about fin whales in Hawaiian waters because they have rarely been sighted during surveys and passive acoustic monitoring has been limited to sparse hydrophone systems that do not have localization capabilities. We hypothesized that fin whale kinematics may be related to their singing behavior, or external variables such as time and sea state. To investigate this hypothesis, we analyzed 115 tracks containing 50,034 unique notes generated from passive acoustic recordings on an array of 14 hydrophones from 2011 to 2017 at the U.S. Navy Pacific Missile Range Facility off Kauai, Hawaii. Fin whales swam at an average speed of 1.1 m/s over relatively direct paths. We incorporated the whales' speed and turning angle into hidden Markov models to identify different behavioral states based on the whales' movements. We found that fin whale kinematic behavioral state was related to the vocalization rate (also known as cue rate) and time of day. When cue rate was higher, fin whales were more likely to swim slower and turn more than when cue rate was lower. During the night, fin whales were also more likely to swim slower and turn more than during the day. In addition, we examined whether the presence of singing fin whales was related to time and sea state using generalized additive models. Fin whale track presence was affected by day of the year and song season, and possibly also wind speed and wave height. Although the track kinematics from the fin whale tracks presented here are limited to a subset of whales that are ...