Potential Masking of the Baltic Grey Seal Vocalisations by Underwater Shipping Noise in the Lithuanian Area of the Baltic Sea

Abstract

Acoustical surveys were completed in the Lithuanian Sea Museum and the Lithuanian area of the Baltic Sea during the period of 2012–2013. Underwater vocalisations of the Baltic grey seals were recorded and collated with underwater shipping noise recorded in the shallow area of the Lithuanian area of the Baltic Sea with the aim to evaluate possible masking of social vocalisations of animals. The following paper focuses not on the complex biomedical auditory or brain stem response research, but on the acoustical measurements and evaluation of possible masking of social vocalisations of grey seals by shipping noise. The results of the survey show masking potential of grey seal communication calls at significant distance in the presence of local shipping noise where the detection distance of calls between conspecifics can be significantly reduced.