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Population Estimates of Right Whales
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Adult right whale off Half Moon Bay, California, March 1982. Note the arch of the head, the curved lower lip and the callosity in front of the blowhole. (The hundreds of white Cornula barnacles around the mouth are anomalous.) |
(updated November 12, 2006) |
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Population Estimates of Right WhalesThe tables below shows estimates of all known right whale populations from the 1998 Report of the Workshop on Comprehensive Assessment of Right Whales:A Worldwide Comparison, a report to the Scientiific Committee of the International Whaling Commission (SC/50/Rep 4). |
Southern Hemisphere (Eubalaena australis)
| Southern Hemisphere Breeding Unit | Estimate of Mature Females (1997) | Estimate of Total Population (1997) |
| New Zealand | 70 | 330 |
| Australia | 254 | 1,197 |
| South Africa | 659 | 3,104 |
| Tristan de Cunha | 48 | 226 |
| Brazil | 29 | 137 |
| Argentina | 547 | 2,577 |
| Chile/Peru | <10 | ? |
| Total: | 1,607 | 7,571 |
North Atlantic (Eubalaena glacialis)
| Estimate of Mature Females (1997) | Estimate of Total Population (1997) | |
| Eastern North Atlantic | 0? | no estimate, but only "sporadic" sightings |
| Western North Atlantic | 74 | 300 |
North Pacific (Eubalaena japonica)
| Estimate of Mature Females (1997) | Estimate of Total Population (1997) | |
| Western North Atlantic | 74 | 300 |
| Eastern North Pacific | >7 | >21 |
Japanese Estimate of 900 Right Whales in the Sea of Okhotsk probably too high
A paper presented to the International Whaling Commission's Scientific Committee Workshop on Right Whales reports 16 sightings of right whales during 1989, 1990 and 1992 in the Sea of Okhotsk. This appears to have involved sightings of 28 individual whales. (The Sea of Okhotsk is the large sea west of the Kamchatka Peninsula in Siberia. It is bordered on the southeast by the Kuril Islands and on the south by Hokkaido, Japan.) From these sightings, they estimate the right whale population in the area at 922 with a 95% confidence interval of 404-2,108. The mean school size was 1.75 whales. (The study has since been published as Miyashita and Kato (2001). The IWC Workshop Report comments:
This estimate is downward biased because (a) the Russian territorial waters (12n miles zone), where right whales are known to occur, were not surveyed; (b) the probability of detection on the track line...was assumed equal to one; and (c) the survey was conducted in closing mode. One factor was noted as possibly positively biasing the estimate: sightings in the eastern area were conducted in August whereas those in the western area were conducted more in September, so that there is was a possiblity of double countings if there was westward migration over this period.
The IWC Workshop Report noted the wide confidence intervals and recommended that a sighting survey specifically for right whales be conducted in this area. It also requested that the Russian Federation be urged to grant permission for vessels to survey within 12n.miles of the Ohkotsk Sea coast.
A more recent analysis of this data suggests that the population estimate extrapolated from this data is too high, and the population there is unlikely to be more than half that size. (Brownell et al. 2001)
Please send any comments or corrections to: Jim Scarff with "right whale" in subject line.