ESR 14:235-242 (2011)  -  DOI: https://doi.org/10.3354/esr00365

ABSTRACT: Multi-locus genotype and sex were used to identify individual bowhead whales Balaena mysticetus from 710 samples collected between 1995 and 2010 at 4 localities in eastern Canada (Foxe Basin, Pelly Bay, Repulse Bay, and Cumberland Sound) and at 1 locality in West Greenland (Disko Bay). In total, 29 recaptures of the same individuals were identified between years, of which 26 individuals were recaptured within the same locality. The remaining 3 were recaptured between sampling localities, from 2 putative International Whaling Commission (IWC) stocks: the Hudson Bay−Foxe Basin stock and the Baffin Bay−Davis Strait stock. These recaptures agree with satellite tracking results that demonstrate movement between IWC stocks and question whether these stocks are true biological entities. The intervals between capture and recapture of females in Disko Bay ranged from 1 to 8 yr. The observed number of multi-year recaptures compared to the expected numbers of recaptures did not indicate any clear cyclicity in the use of Disko Bay consistent with the notion that the migration pattern of females to this area might be tied to their reproductive cycles. A mark−recapture estimate of whales identified in 2010 compared to all identifications between 2000 and 2009 resulted in an estimate of 1410 bowhead whales (SE = 320, 95% CI: 783−2038) constituting the spring aggregation in Disko Bay. The estimate for the female portion of the aggregation was 999 individuals (SE = 231, 95% CI: 546−1452). The multi-year cycle of appearance in Disko Bay emphasizes the necessity for identifying whales over multiple years for inclusion in mark−recapture estimation.

KEY WORDS: Bowhead whale · Balaena mysticetus · Genotyping · Recapture · Stock structure · Abundance · Mark–recapture