Abstract

Marine mammals’ dependency on their auditory sense is undisputed and is used for navigation, foraging, and communication, and beluga whales (Delphinapterus leucas) are among the most vocal cetaceans.¹ Evidence exists for correlation of beluga vocalizations with their behavior, and this may make them more vulnerable if anthropogenic noise is shown to alter their vocalizations.² The objective of this study was to determine whether there is a difference in the average formant value (harmonic of a fundamental pitch) in the vocalizations of beluga whales between geographic locations on the northeastern inland coast of Canada and the northeastern coast of the United States. The hypothesis was that the formant value in the vocalizations of belugas from East Cumins Inlet, ME and New York Aquarium, NY will be significantly higher than those of the belugas from Passe Pierre, Baie Ste. Catherine, Ile aux Coudres, and the Saguenay River in Canada based on estimated levels of low-frequency anthropogenic noise at these locations, suggesting a possible beluga compensatory response of raising the pitch of their calls. Recordings of beluga vocalizations from the open-source Watkins Marine Mammal Sound Database (recorded in 1949, 1962–63, 1965, and 1968; the only years with available recordings) were downloaded and analyzed via frequency analysis software to find the first formant value of each recording. These data were then analyzed using means, linear regressions and corresponding graphs, and the chi-square test of mathematical significance. The formant values in recordings from the eastern coast of the United States were indeed higher (statistically significant; calculated chi-square value of 67.171 as compared to a critical value of 11.070) than those from northeastern inland Canada, thus supporting the hypothesis. However, other factors apart from anthropogenic noise may have contributed to these results, and further investigation is needed.

Because NOAA considers anthropogenic noise to be a threat of high concern to beluga whales, and given the results of this study suggesting a correlation between formant values of beluga vocalizations and geographic locations (and the presumed anthropogenic associated noise at those locations), there is a dire need for further study: Shipping noise has had a documented increase by 12 dB as of 2009; detailed maps of oceanic anthropogenic noise are lacking or unavailable, at least online; and there is a lack of research on the effects of manmade noise on other species of marine mammals.^3,4 Auditory senses are vital to belugas and other cetaceans, and this study suggests that belugas may be altering their vocalizations to compensate for changes in their auditory environment.

Acknowledgements

The author wishes to thank her research advisor and biology teacher, Mrs. Suzanne Monck, who provided helpful comments on the rough draft of the paper; her classmate Arav Agarwal, who took time to explain higher mathematical and physics concepts; the Woods Hole Oceanographic Institution, for providing free online access to the recordings in the Watkins Marine Mammal Sound Database; and her parents, for supporting her research endeavors.

* Presenting author

Literature Cited

1.  Sam H. Ridgway. 1972. Mammals of the Sea: Biology and Medicine. Springfield: Charles C. Thomas.

2.  SeaWorld Parks & Entertainment. 2017. Beluga communication & echolocation. Website: https://seaworld.org.

3.  NOAA Fisheries. 2017. Beluga whale (Delphinapterus leucas). Website: National Oceanic and Atmospheric Administration.

4.  John A. Hildebrand. 2009. Anthropogenic and Natural Sources of Ambient Noise in the Ocean. 395th ed. Marine Ecology Progress Series. p. 5–20.