Comments: Bowhead whales and right whales often have been included in the same genus (Balaena) (e.g., Rice 1998), but most recent classifications recognize them as distinct genera (Balaena for bowhead whale, Eubalaena for right whales) (e.g., Baker et al. 2003; Mead and Brownell, in Wilson and Reeder 2005). MtDNA data are consistent with recognition of Balaena and Eubalaena as distinct genera (Rosenbaum et al. 2000).

A strong consensus does not exist regarding the taxonomic status of the various populations of right whales. Based on mtDNA data, Rosenbaum et al. (2000) proposed that the North Atlantic, North Pacific, and Southern Hemisphere populations could be recognized as distinct species (E. glacialis, E. japonica, and E. australis, respectively). Baker et al. (2003) argued against this proposal, noting among other things that no other consistent differences have been found among the three populations. The recovery plan for this species and Mead and Brownell (in Wilson and Reeder 1993) regarded the southern right whale (E. australis) as a distinct species, but Rice (1998) and Baker et al. (2003) included australis in Eubalaena (or Balaena) glacialis. Mead and Brownell (in Wilson and Reeder 2005) cited Rosenbaum et al. (2000) in recognizing E. glacialis, E. australis, and E. japonica as distinct species.

Recent analysis of mtDNA and nuDNA strongly supports the hypothesis of three genetically distinct species, despite the lack of any diagnostic morphological characters, thereby providing genomic justification for the recognition of E. japonica as a distinct species in the North Pacific (Gaines et al. 2005). A genetic study of cyamid populations (whale lice) found only on right whales suggests these amphipod crustaceans have been fully (or almost fully) isolated for several million years (Kaliszewska et al. 2005). This finding also strongly supports the view that North Atlantic, North Pacific, and southern populations of right whales should be considered distinct species.