title: Source level estimates for sei whale (Balaenoptera borealis) vocalizations off the Azores.
abstract: Sei whale calls have been documented on very few occasions and never in the Azores Archipelago, an area transited by this species during their migration to northern latitudes in spring and early summer. Using a combination of video range tracking (VRT) and acoustic methods, vocalizations are described from an encounter with two sei whales in April 2012 off Pico Island, Azores. Recordings analyzed post-survey revealed 53 low frequency downsweep calls with average maximum frequencies of 100 Hz [standard deviation (SD = 14 Hz)] down to 37 Hz (SD = 8 Hz) over 1.21 s (SD = 0.33 s). Apparent source levels of 177 dB (SD = 5 dB) root-mean-square (rms) re 1 μPa were recorded. Vocalizations were attributed to the pair of sei whales encountered using a combination of the VRT data and differences in arrival time of calls at the hydrophones. These calls are similar to those reported from sei whales off New England and similar to those recorded off Hawaii. The growing body of acoustic data on sei whale vocalizations may contribute to the understanding of this species' distribution and population identity; key information is needed to guide future conservation efforts for this species.
authors.affiliation: Marine Conservation Research International, 1 High Street, Kelvedon, Colchester CO5 9AG, United Kingdom.
authors.forename: Miriam
authors.initials: M
authors.lastname: Romagosa
authors.affiliation: Marine Conservation Research International, 1 High Street, Kelvedon, Colchester CO5 9AG, United Kingdom.
authors.forename: Oliver
authors.initials: O
authors.lastname: Boisseau
authors.affiliation: Marine Conservation Research International, 1 High Street, Kelvedon, Colchester CO5 9AG, United Kingdom.
authors.forename: Anna-Christina
authors.initials: AC
authors.lastname: Cucknell
authors.affiliation: Marine Conservation Research International, 1 High Street, Kelvedon, Colchester CO5 9AG, United Kingdom.
authors.forename: Anna
authors.initials: A
authors.lastname: Moscrop
authors.affiliation: Marine Conservation Research International, 1 High Street, Kelvedon, Colchester CO5 9AG, United Kingdom.
authors.forename: Richard
authors.initials: R
authors.lastname: McLanaghan
mesh_terms: D025041:Animal Migration; D000818:Animals; D001267:Atlantic Ocean; D050616:Balaenoptera / Q000502:physiology*; D001522:Behavior, Animal; D056727:Endangered Species; D012919:Social Behavior; D014741:Video Recording / Q000295:instrumentation / Q000379:methods; D014828:Vocalization, Animal