Eubalaena japonica (Northeast Pacific subpopulation)

Subpopulation of Eubalaena japonica (Lacépède, 1818).  The taxonomy follows the view of the International Whaling Commission (IWC) Scientific Committee  (IWC 2004) and Convention on Migratory Species, which recognize right whales in the North Atlantic, North Pacific and Southern Hemisphere as three distinct species in the genus Eubalaena, namely E. glacialis (North Atlantic right whale), E. japonica (North Pacific right whale) and E. australis (southern right whale), based mainly on the mtDNA phylogenetic analyses of Rosenbaum et al. (2000).

In most of the scientific literature prior to 2000, including previous Red Lists (e.g. Baillie and Groombridge 1996), all Northern Hemisphere right whales are treated as the single species E. glacialis.

Rice (1998) classified right whales in the North Atlantic, North Pacific and Southern Hemisphere as the single species Balaena glacialis (in the genus Balaena along with B. mysticetus, the bowhead whale). While not all cetologists accept that the three right whale taxa qualify as full biological species, their clear geographical separation ensures that no practical problem arises from treating them as distinct species.

Based on their different catch and recovery histories, right whales in the eastern and western North Pacific are considered separate subpopulations with little or no genetic exchange (Brownell et al. 2001).

Prior to the onset of commercial whaling in the 1830s, right whales were widely distributed across the North Pacific (Scarff 1986, Clapham et al. 2004, Shelden et al. 2005). In the eastern North Pacific, the waters adjacent to the Aleutian Islands and much of the Bering Sea below 60^oN were major feeding grounds during spring, summer and autumn, as was virtually the entire Gulf of Alaska. Neither the historical nor the present-day breeding/calving grounds for this subpopulation have been identified. 

In recent decades, both the southeastern Bering Sea and the western Gulf of Alaska (shelf and slope waters south of Kodiak) have been the focus of sightings as well as illegal Soviet catches (see below). Recent acoustic detections of right whale calls have been made in both areas using autonomous recording packages deployed for extended periods (Moore et al. 2006). They confirm the presence of right whales in the southeastern Bering Sea from May into November; records from the Gulf of Alaska are somewhat more sporadic, but include detections in August and September.

Seasonal movements are evident in sighting and catch data from the 20^th century, with a general northward migration into the Gulf of Alaska and Bering Sea in spring and summer, and a gradual movement away from these areas in autumn (Clapham et al. 2004, Shelden et al. 2005). There are very few records of right whales anywhere in the North Pacific in winter.

In general, the majority of eastern North Pacific right whale sightings (historically and in recent times) have occurred from about 40º N to 60º N. There are historical records from north of 60º N, but these are rare and many are likely to be misidentified bowhead whales. Right whales have on rare occasions been recorded off California and Mexico, as well as off Hawaii. However, as noted by Brownell et al. (2001), there is no evidence that either Hawaii or the west coast of North America from Washington State to Baja California has ever been important habitat for right whales. Consequently, the few records from this region are considered to represent vagrants.

As noted above, right whales in the eastern North Pacific are considered to be separate from those in the west on the basis of distinct catch and recovery histories (Brownell et al. 2001, IWC 2001). The right whale population throughout the North Pacific is only a small fraction of what it was prior to 19^th century whaling. A preliminary estimate of 26,500-37,000 animals taken (including struck and lost) throughout the entire North Pacific during the period 1839-1909 was given by Scarff (2001), of which 21,000-30,000 were taken during 1840-49 alone.

In the eastern North Pacific between 1941 and 1964, there were 598 sightings of right whales; in contrast, in the period 1965-1999 there was a total of only 82 sightings in this region (Brownell et al. 2001). The dramatic decrease was due to illegal Soviet catches of 372 whales in the Bering Sea and Gulf of Alaska, mainly in the period 1963-66 (Doroshenko 2000); given the paucity of sightings in subsequent years, this catch total may well have constituted the bulk of the remaining subpopulation. In all, 411 right whales were killed in the eastern North Pacific in the 20^th century (Brownell et al. 2001).

The few animals observed in the eastern North Pacific today are often alone and are scattered in their distribution. The only exception is an area of the southeastern Bering Sea where small groups of right whales have been seen in several successive years (LeDuc et al. 2001); in 2004, a recorded group of at least 17 individuals represented the largest sighting since the Soviet catches of the 1960s (Wade et al. 2006). No quantitative estimate of abundance is available, but the paucity of sightings suggests that right whales in the eastern North Pacific number only in the tens (Brownell et al. 2001). Furthermore, the reproductive rate appears to be low: there have been only three records of calves since directed survey effort began in 1998 (Waite et al. 2003, Wade et al. 2006).

Little is known about habitat use by eastern North Pacific right whales. The rarity of coastal records in winter in either historical or recent times suggests that their breeding grounds may have been offshore (Clapham et al. 2004). This is in contrast to southern and North Atlantic right whales, both of which form inshore breeding concentrations. There is clearly some northward migration in summer and southward in winter (Clapham et al. 2004), but the location of the wintering grounds is unknown. The historical catches show that in summer the population occurred mainly on feeding grounds in the Bering Sea and Gulf of Alaska. Data on food habits are sparse, but suggest that right whales in the eastern North Pacific feed primarily on copepods of the genera Calanus and Neocalanus (Shelden et al. 2005). Primary habitats today include core areas of the southeastern Bering Sea and an area off eastern Kodiak Island, which were also significant parts of the range in the past.

Commercial hunting for right whales in the eastern North Pacific was initiated by Europeans and Americans in the 1830s; by about 1900, the subpopulation had been reduced to a fraction of its original abundance, as evidenced by the comparatively low number of 20^th century sightings (Brownell et al. 2001). Although legally protected by the IWC since 1946 (and by an earlier agreement in 1935), illegal hunting continued into the 1960s with the Soviet catches of 372 animals in the eastern North Pacific (Doroshenko 2000, Brownell et al. 2001).

 There is currently no evidence of human-related mortality or injury, but the very low observer effort and remoteness of the right whale’s habitats probably means that most deaths and injuries pass unrecorded.

 The eastern North Pacific subpopulation is subject to anthropogenic threats such as entanglements in fishing gear, disturbance by vessels and other noise, collisions, and possibly petroleum-related and other contaminants.

 As compared with the intensively studied North Atlantic right whale, the more offshore and remote distribution of eastern North Pacific right whales may be an advantage in terms of less intensive exposure to human impacts, but the disadvantage is that impacts that do occur are less likely to be detected and their consequences are harder to ascertain and evaluate.

 Small populations numbering less than a few hundred individuals can have a number of interacting effects that accelerate overall risk (Gilpin and Soule, 1986).  Among those effects are demographic stochasticity, inbreeding depression and density depensation (Allee effects).  Although direct data are lacking for marine mammals at low density, the expectation is that these threats could be serious because cetaceans are social animals with low reproductive output.

North Pacific right whales were legally protected from commercial whaling through international agreements in 1935 and 1946, but this has been fully respected in practice only since the 1970s. A Recovery Plan has been developed by the US National Marine Fisheries Service, but to date the only conservation measure undertaken has been the designation in 2006 of two areas of Critical Habitat (the southeastern Bering Sea and a small region off eastern Kodiak Island) under the US Endangered Species Act.

The species is listed in Appendix I of both CITES and CMS.