Silent porpoise: potential sleeping behaviour identified in wild harbour porpoises

摘要: All animals sleep and it is essential for maintaining optimal brain function. However, cetaceans engage in the unusual practice of unihemispherical sleep, where only half their sleeps at a time, due to constant need movement breathing. Most studies have occurred captivity. tagging devices now developed point data collected from wild can be assessed against published criteria defining behaviourally. Seven acoustic behavioural loggers were deployed on harbour porpoises, Phocoena phocoena, Danish waters between May 2010 August 2011 stayed 53 72 h, recording 1884 2755 valid dives per animal. Parabolic with significantly reduced bioacoustic activity stereotyped pattern identified as potential sleeping periods. The recordings nearly parabolic found contain no vocalization (echolocation clicks), more than other dive types. Of remaining dives, click rate was, when normalized individual means, also lower detected Additionally, shallow compared all types, stereotypic low-energy profile. They fewer rolls incorporate vertical descent most If are representative, porpoises spend small, but meaningful amount diving time engaged thus potentially sleeping. fundamental undisturbed sleep. These quiet periods considered anthropogenic effects, those employing passive monitoring techniques, well efforts reduce incidental bycatch fisheries, given associated environmental awareness.