Thumbnail Image

Group behavioural responses of cyprinids to artificial acoustic stimuli: implications for fisheries management

Physical screens are considered a necessary mitigation strategy, restricting access to hazardous areas (e.g. turbine intakes or extraction points) and guiding fish to safer preferred routes. Whilst this precautionary approach is considered fit for purpose, fish interactions at such interfaces have been observed to cause stress, injury and mortalities where high sweeping approach velocities exist. Alternative or collaborative systems may allow for improvements where effectiveness of physical screens alone are limited (e.g. repelling small sized larval/ juvenile stages). A number of acoustic guidance systems have been deployed to date, however efficiencies of such devices are measured using relatively simplistic metrics (e.g.percentage deflection or attraction). Results are highly variable, with some systems observing little to no deflection. Current approaches testing efficiencies are based on methods which provide limited information surrounding the wild behaviour of migratory fish. Furthermore, many studies investigating fish bioacoustics pay limited attention to the entirety of the acoustic field to which fish are exposed. The auditory system is exceptionally important to most aquatic species due to its information provisioning, however various challenges need addressed to extrapolate useful informative data which could develop working behavioural deterrents. Life-history strategies, life-stages, species specific hearing capabilities (i.e. directivity index, sensitivity, and critical ratio), and the propensity for a sound to elicit a repeatedly effective behavioural response (i.e. signal detection theory and effects of habituation) are all areas that require thorough investigation. Utilising model cyprinid species (in possession of morphological hearing specialisations), groups of fish were video recorded under controlled conditions and exposed to differing acoustic stimuli. Behaviours were quantified and analysed, alongside appropriate mapping of tested acoustic fields. This talk summarises past and ongoing experiments of a PhD project investigating group behavioural responses to sound. Results may better inform fisheries engineering design of acoustic behavioural deterrents for conservation and control purposes.