Informing acoustic deterrence through quantification of innate behavioural responses of fish to short-duration pure tones

Abstract

This thesis aimed to inform acoustic deterrence through quantification of innate behavioural responses of fish to short-duration pure tones. To fulfil this aim, a set of objectives were developed, returning to first principles, to achieve optimum avoidance using startle responses as a proxy for deterrence: (1) determine the startle response threshold in goldfish to pure tone acoustic stimuli; (2) quantify innate responses of goldfish responding to a 120 ms pure tone acoustic stimulus in presence and absence of band-limited (100 – 2500 Hz) random noise; (3) utilise the temporal characteristics of fish sounds to inform acoustic deterrence and identify the optimal temporal sound characteristics to elicit an avoidance response. All experiments used goldfish – a species with well-understood hearing abilities. Prior to commencing experiments with fish, a methodological study was undertaken, which provided a unique set up in which a cylindrical tank was submerged in a large water body to produce a heterogeneous and replicable sound field for subsequent experiments. The first of the experiments identified the optimum frequency to elicit a startle response in individual goldfish as being different to the frequency of best hearing. The second found that adding background noise introduced stochastic resonance, whereby the noise acted as a primer for responses to a pure tone acoustic stimulus. The metaanalysis concluded that it was not possible to generalise the temporal characteristics, such as pulse period or pulse duration, that would be ideal for acoustic deterrents. Towards the end of the thesis, the ideal conditions for implementing acoustic deterrents successfully were discussed, as well as how the experimental findings can be built upon for future studies. This research may help alleviate the ecological impacts of river infrastructure and environmental stressors such as invasive species.

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Identifiers

ORCID for Amelia Holgate: orcid.org/0000-0002-9648-3152

ORCID for Paul Kemp: orcid.org/0000-0003-4470-0589

ORCID for Paul White: orcid.org/0000-0002-4787-8713

ORCID for Timothy Leighton: orcid.org/0000-0002-1649-8750

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