title: Vocalisations of the bigeye Pempheris adspersa: characteristics, source level and active space.
abstract: Fish sounds are an important biological component of the underwater soundscape. Understanding species-specific sounds and their associated behaviour is critical for determining how animals use the biological component of the soundscape. Using both field and laboratory experiments, we describe the sound production of a nocturnal planktivore, Pempheris adspersa (New Zealand bigeye), and provide calculations for the potential effective distance of the sound for intraspecific communication. Bigeye vocalisations recorded in the field were confirmed as such by tank recordings. They can be described as popping sounds, with individual pops of short duration (7.9±0.3 ms) and a peak frequency of 405±12 Hz. Sound production varied during a 24 h period, with peak vocalisation activity occurring during the night, when the fish are most active. The source level of the bigeye vocalisation was 115.8±0.2 dB re. 1 µPa at 1 m, which is relatively quiet compared with other soniferous fish. Effective calling range, or active space, depended on both season and lunar phase, with a maximum calling distance of 31.6 m and a minimum of 0.6 m. The bigeyes' nocturnal behaviour, characteristics of their vocalisation, source level and the spatial scale of its active space reported in the current study demonstrate the potential for fish vocalisations to function effectively as contact calls for maintaining school cohesion in darkness.
authors.affiliation: Leigh Marine Laboratory, Institute of Marine Science, University of Auckland, PO Box 349, Warkworth 0941, New Zealand c.radford@auckland.ac.nz.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Radford
authors.affiliation: Leigh Marine Laboratory, Institute of Marine Science, University of Auckland, PO Box 349, Warkworth 0941, New Zealand Marine Ecosystem Research Centre (EKOMAR) and School of Environment and Natural Resources, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Malaysia.
authors.forename: Shahriman
authors.initials: S
authors.lastname: Ghazali
authors.affiliation: Leigh Marine Laboratory, Institute of Marine Science, University of Auckland, PO Box 349, Warkworth 0941, New Zealand.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Jeffs
authors.affiliation: Leigh Marine Laboratory, Institute of Marine Science, University of Auckland, PO Box 349, Warkworth 0941, New Zealand.
authors.forename: John C
authors.initials: JC
authors.lastname: Montgomery
mesh_terms: D000162:Acoustics; D000818:Animals; D002940:Circadian Rhythm; D009520:New Zealand; D010473:Perciformes / Q000502:physiology*; D013018:Sound Spectrography; D014828:Vocalization, Animal
keywords: Active space; Ambient sound; Contact call; Fish; Vocalisations