North Pacific right whale (Eubalaena japonica) COSEWIC assessment and status report: chapter 7

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Population Sizes and Trends

The pre-exploitation abundance of North Pacific right whales has been estimated to be more than 11,000 animals (NMFS 1991) and perhaps twice that number (Scarff 2001). Today they are extremely rare in the eastern North Pacific, having been reduced to near extinction by 19^th century pelagic whaling and illegal Soviet whaling in the 1960s (Scarff 1991, Doroshenko 2000, Brownell et al. 2001). 

Since 1997, there have been a few sightings of eastern North Pacific right whales in the southeastern Bering Sea and acoustic data suggest that the animals remain there from August until November (Munger et al. 2003). LeDuc et al. (2001) reported on the identification of 11 individuals using photographic techniques. These 11 animals were all biopsy sampled. On the basis of genotypes, there were only six unique individuals thus the total number of individuals represented by the 11 animals was six (LeDuc et al. 2001). All six were genetically sexed as males; two haplotypes were represented (LeDuc et al. 2001). Among nine additional photographed sightings in 2002 was one mother with a calf (LeDuc 2004). An aggregation of 25-30 animals, including 2-3 cow-calf pairs, was observed in the southeastern Bering Sea during the summer of 2004 (Robert Pitman, Southwest Fisheries Center, NMFS, personal communication). The implication from the preliminary genetic work that females may be few in number must be tempered by the possibility that males may be easier to biopsy sample or there is geographic segregation by sex on the summering grounds (LeDuc et al. 2001). Based on the extensive area surveyed (LeDuc et al 2001, LeDuc 2004) and clustering of the sightings it is possible that the population in the eastern North Pacific could be as low as a few tens of animals.