Forsøksdyr: Live capture and release of minke whales for the collection of auditory evoked potential hearing thresholds

Godkjenningsdato 21.05.2019

Godkjenningsperiode 01.01.2021-31.12.2022

The impact of anthropogenic noise on marine mammals is a global concern, particularly the impact of ocean noise on mysticete (baleen) whales, which produce communication signals at frequencies where ocean noise is greatest (<1kHz). Since whales rely on sound for survival and reproduction, it is vital to understand their hearing abilities to assess the impact of human-made sound. Estimates of the ability of mysticetes to detect, and be impacted by human noise sources, is hindered by the fact that there have been no empirical measures of hearing in any mysticete whale. Estimates of hearing abilities in mysticetes have largely been based on anatomical predictions, frequencies at which animals vocalize, or observations of behavioral responses to noise. Unfortunately, each of these approaches has serious drawbacks and leaves great uncertainty as to what mysticete whales can hear. To effectively predict the impact of human-caused noise on mysticete whales and validate anatomical models of whale hearing, direct measurements of hearing in at least one representative mysticete whale needs to be performed. The effort described in this protocol will be to use auditory evoked potentials (AEP) to assess hearing in one of the smallest mysticete whales, the minke whale. The AEP-method measures electrical signals generated by the auditory system when an animal hears a sound. Since mysticetes are not available at any facility that holds marine mammals, wild minke whales will be caught, kept in a natural enclosure for 3-4 days, and then released after the AEP-hearing test has been completed. Before release a satellite tag will be placed on the dorsal fin to monitor the whale’s behaviour following the treatment.
A total of 12 animals will be used for AEP hearing test and equipped with satellite tags. The experimental procedure involves moderate distress and discomfort for up to six hours. No alternative to experimental studies was found, but an important step in this study is the optimization of electrophysiological techniques to measure hearing in mysticetes. If successful, the AEP method can in the future be used on stranded animals, reducing the need for further experimental studies on wild-caught animals.Information obtained from this study will also be used to validate alternative techniques, such as anatomical modelling. If model validation can be completed, the number of animals used in experimental studies may be reduced in the future. A specific safety protocol has been established to minimized risk to the animal. This includes human end points, health monitoring in all phases and if needed use of sedation to reduce stress.
This is a very novel research project. Audiograms have never been meausred in any baleen whales before, nor have anyone before succesfully captured a baleen whale. The international researh team are very experienced, either working with minke whales in the field or hearing studies in other ceteacean sepecies..