Seasonal presence of ringed, ribbon, and bearded seal vocalizations in the Chukchi Sea north of Barrow, Alaska

Abstract

Long-term autonomous acoustic recordings were collected between September and June from 2006 through 2009 in the Northeastern Chukchi Sea along the continental slope 120 km north of Barrow, Alaska. These recordings were analyzed for the presence of vocalizations of ringed seals (Phoca hispida), ribbon seals (Histrophoca fasciata), and bearded seals (Erignathus barbatus). We present detailed descriptions of the acoustic repertoire of each species in addition to three-year time series of seal vocalizations and mean daily sea ice concentration. Ringed seal vocalizations are present throughout each winter and spring, indicating that they both overwinter and breed in offshore pack ice. Ribbon seal calls occur only during the open water period in 2008, but their acoustic behavior is more varied than previously described. Bearded seal vocalizations closely match well-documented calls recorded offshore near Point Barrow but have shorter duration and smaller frequency range, suggesting that demographic or behavioral differences related to breeding habitat selection may exist within the population. Bearded seal calls peak during the breeding season from March through June, but also occur in December and January annually. These long-term autonomous recordings provide details of seasonal distribution and behavior of Arctic seals that previously have not been possible to observe with other methods.