Investigation of the ability of gray seals to differentiate composite audio signals

• Published in: Vestnik MGTU
• Main Authors: Y. V. Litvinov, M. V. Pakhomov
• Format: Article in Journal/Newspaper
• Language: Russian
• Published: Murmansk State Technical University 2019
• Subjects: gray seal; acoustic noise; sound stimulus; серый тюлень; акустический шум; звуковой стимул; General Works; A; Kola Bay
• Online Access: https://doi.org/10.21443/1560-9278-2019-22-2-249-257; https://doaj.org/article/0d037bc542374f008efd7488a1bc59cd

Technogenic noise pollution of the seas and oceans has a significant impact on the physiology and behavior of marine mammals. The ability of gray seals to memorize and differentiate complex acoustic signals with similar amplitude-frequency characteristics has been analyzed while studying this impact. The experiment consisted of three stages. At the first stage, the seals were trained to press the pedal only when a certain sound signal was given. At the second stage, the second sound signal was added, in frequency characteristics significantly different from the reinforced signal. At the third stage, the third sound signal was added close in frequency characteristics to the supported one. At each stage, 12 experiments were conducted, the number of stimulus presentations was not limited, the experiment was considered complete when the seal made 20 correct choices. The sound stimuli used were sound recordings of diesel engines at idle. The experiment was conducted in the MMBI aquacomplex located in the Kola Bay (the town of Polyarny). The experimental animals were 4 species of the gray seal (Halichoerus grypus Fabricius, 1791) of different ages: seals No. 1 and No. 2 – 12-year-old females, seal No. 3 – 2-year-old female, seal No. 4 – 2-year old male. During the experiment, it has been shown that the reproduced sound of a diesel engine at a sound pressure level of 60–70 dB is a perceived sound stimulus for gray seals. At the first demonstration of a sound stimulus in seals, behavior characteristic of the reaction to avoid a new unknown stimulus has been noted, and no further reaction has been observed in the experimental seals. Later on, the seals have managed to develop a stable differentiating conditioned reflex to a given sound stimulus, which all the investigated seals have reliably distinguished from similar stimuli. It has been found that the time of onset of the response to an external stimulus presented is of an individual character in gray seals.