Research Document - 2011/029

Aerial survey estimates of hauled-out Ringed Seal (Pusa hispida) density in western Hudson Bay, June 2009 and 2010

By S.H. Ferguson and B.G. Young

Abstract

We conducted strip-transect surveys in June 2009 and 2010 to estimate density and abundance of Ringed Seals (Pusa hispida) in western Hudson Bay, Canada. Ringed Seal density has varied considerably over the 16-year period of aerial surveys. Recent survey results describe a decrease in Ringed Seal density from 1.06 seals/km² in 2007, to 0.50 in 2008, and 0.28 in 2009, followed by an increase to 0.73 in 2010. However, estimates from 2009 should be considered cautiously due to an incomplete survey caused by poor weather and ice conditions. Our results add to a long time-series of Ringed Seal density and abundance in the Arctic. A declining, albeit not significant, trend in Ringed Seal density estimates in western Hudson Bay is evident over the past sixteen years based on results obtained from nine aerial surveys which include the 2009 and 2010 surveys. As Ringed Seals are considered to be a good indicator species of long-term changes, continued monitoring of population density will add to an understanding of biological mechanisms of population response to environmental forcing.

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