Dear colleagues, We are pleased to share the publication of our new paper "Seasonal occurrence of fin whale song off Juan Fernandez, Chile, by Susannah Buchan, Laura Gutierrez, Naysa Balcazar-Cabrera and Kathleen Stafford, in Endangered Species Research. The abstract can be found following this meesage, and an open access copy of the full paper can be dowloadad at: https://www.int-res.com/abstracts/esr/v39/p135-145/ . All the best, Susannah *Abstract* Fin whales (*Balaenoptera physalus*) were the most widely caught species of baleen whale by commercial whaling fleets off the Chilean coast and are globally classified as Endangered by the International Union for Conservation of Nature, however very little is known about the present distribution and seasonal movements of fin whales off the coast of Chile. Passive acoustic data collected at the HA03 station of the *Preparatory Commission* for the *Comprehensive Nuclear* *Test* *Ban* Treaty Organization off the Juan Fernandez Archipelago (JFA) between 2007 and 2016 were analyzed. The temporal occurrence of fin whale song was examined using automatic detection via spectrogram cross-correlation of song pulses, and by calculating the average acoustic power in the frequency bands of fin whale song. Fin whale song off JFA was composed of regular ~17 Hz pulses associated with pulses at ~86 Hz, with singlet phrasing at an inter-pulse interval of ~14.4 s. There was a clear seasonal pattern in acoustic presence that was consistent across all years: low or no song occurrence in the austral summer and a peak in song occurrence during the austral winter. A propagation loss model estimated detection range at this site to be 50 km. Where the fin whales that are heard off JFA spend the summer months remains an open question. Possible locations include the Western Antarctic Peninsula and/or northern-central mainland Chile. Further studies should be pursued to better understand the distribution and seasonal movements, and support the conservation of this Endangered species. -- Susannah J. Buchan, PhD Associate Researcher, COPAS Sur-Austral, University of Concepción Researcher, CEAZA Research Center Guest Investigator, Woods Hole Oceanographic Institution. Email: sbuchan@udec.cl/sjbuchan@gmail.com Cel. Chile: +56 9 6646 8466/ Cel. USA: +1 323 571 7641 Skype: susannah.buchan