Fin whale (Balaenoptera physalus) acoustic presence off Elephant Island, Antarctica

• Main Authors: Burkhardt, Elke, Boebel, Olaf, Ciesewski, Boris, Mattmueller, Ramona Maja, Meister, Marlene, Schall, Elena, Spiesecke, Stefanie, Thomisch, Karolin, van Opzeeland, Ilse
• Format: Conference Object
• Language: unknown
• Published: 2018
• Subjects: Antarc*; Antarctica; Balaenoptera physalus; Elephant Island; Fin whale
• Online Access: https://epic.awi.de/id/eprint/47472/; https://epic.awi.de/id/eprint/47472/2/Poster_ECS_2018.pdf; https://hdl.handle.net/10013/epic.06ef2e96-c542-49c2-91e9-e5ca8a61886c

Recent visual observations suggest that the region around Elephant Island serves as an important feeding area for fin whales. Passive acoustic recordings collected northwest of Elephant Island (61°0.88’S, 55°58.53’W) from January 2013 to February 2016 were analysed manually for seasonal and diel patterns of fin whale 20 Hz calls. Overall, calls were detected year-round, although in some years calls were not present during all months. For all years, fin whale calls were consistently present from February to July for more than 90% of days per month. From August to January, percentage of days with calls varied between years, with presence exceeding 75% of days per month throughout 2014, whereas in 2015 calls were absent in October and November. In 2013, fin whale calling dropped in August and increased again towards November (present 80% of days per month). Diel patterns in call activity were analysed for a 10-month subset of the data from 2013. Fluctuations in call rates did not follow a diel pattern nor correspond to local insolation. During peak calling period, maximum calls amounted approximately to 80 per 10-minute file. Fluctuations in call presence outside the peak calling period may be explained by variation in local ice conditions as drift may temporally force the animals away to areas with reduced ice concentrations. Furthermore, delays in the timing of migration between age groups, sexes and/or reproductive classes may also affect temporal patterns in the clustering of calls. The observed peaks in fin whale call activity correspond to the periods during which fin whale super groups have been repeatedly observed visually in this region. Our year-round acoustic analysis indicates that the Elephant Island region is likely to play an important role for fin whales throughout the remainder of the year.