Bowhead whales Balaena mysticetus in the Okhotsk Sea

1. Little is known about the endangered population of bowhead whales Balaena mysticetus in the Okhotsk Sea (OS). Here, we review existing information about this stock, including much material published in Russian. 2. Whaling for OS bowheads began around 1846, was pursued intensively for two decades and continued sporadically until about 1913. Beginning in 1967, whalers from the USSR killed bowheads illegally, although the number of whales taken remains unknown. Estimates of the pre-exploitation population size have ranged from 3000 to 20000 whales, but all such estimates are based upon untested assumptions and incomplete data. 3. Information on historical and current distribution of bowheads comes from whaling records (notably Townsend 1935 ) and from modern (notably Russian/Soviet) marine mammal surveys. Little is known about winter distribution. During spring and summer, known bowhead concentrations occur in Shelikhov Bay and at Shantar. Although historical whaling data show bowheads in Shelikhov Bay during summer and early autumn, there have been no recent sightings later than June. However, extensive 19th century catches were made over much of the northern OS, and the present range and habitat use of the population is probably broader than existing data suggest. There is evidence for age or maturational class segregation between Shantar and Shelikhov Bay; the former hosts immature whales and lactating females, and the latter hosts adults. 4. Genetic data indicate that the OS bowhead stock is separate from the Bering-Chukchi-Beaufort population, but that the two populations share a common ancestry. There is no evidence that bowheads ever leave the OS. 5. Russian observers have put the current size of the OS stock in the low hundreds, but this is not based on quantitative analysis. Overall, the OS bowhead population is very likely to be relatively small; it did not recover from the intensive whaling in the 19th century, and the illegal Soviet catches of the 1960s have further set back its recovery. Dedicated surveys and other research are required to assess the status and conservation needs of the population.