Balaena mysticetus (Okhotsk Sea subpopulation)
|Scientific Name:||Balaena mysticetus (Okhotsk Sea subpopulation)|
|Taxonomic Notes:||A subpopulation of Balaena
mysticetus Linnaeus, 1758. See also global assessment for this species and
subpopulation assessment for the
|Red List Category & Criteria:||Endangered D ver 3.1|
|Assessor(s):||Reilly, S.B., Bannister, J.L., Best, P.B., Brown, M., Brownell Jr., R.L., Butterworth, D.S., Clapham, P.J., Cooke, J., Donovan, G., Urbán, J. & Zerbini, A.N.|
|Reviewer(s):||Taylor, B.L. & Notarbartolo di Sciara, G.|
The available, albeit tentative information on abundance suggests that the mature population size is below 250 individuals.
|Previously published Red List assessments:|
Sea of Okhotsk from Shantarskiye Zaliv east to Zaliv Shelikova, Gizhiginskaya Guba and Penzhinskaya Guba (Moore and Reeves 1993, Rice 1998). The absence of bowhead sightings on any of the Japanese-Russian systematic surveys of cetaceans in the Okhotsk Sea conducted in 1989, 1990, 1998, 1999, 2000 and 2003 (Miyashita and Dorosehnko 1990; Miyahsita and Berzin 1991; Miyashita et al. 2000, 2001; Miyashita 1999, 2004) tends to confirm that animals from this subpopulation are rarely found outside those four known areas of concentration.
The map shows where the species may occur based on oceanography. The species has not been recorded for all the states within the hypothetical range as shown on the map. States for which confirmed records of the species exist are included in the list of native range states.
|FAO Marine Fishing Areas:|
Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Bowhead Whales have been seen regularly during Russian surveys in the northeast and southwest Sea of Okhotsk. Berzin et al. (1991) reported bowhead sightings every year from 1982 through 1990, except 1985, with up to 72 whales apparently seen on one day. Doroshenko and Ivannikov (2003) reported 48 Bowhead Whales sighted during a not especially intensive survey conducted in 2001. |
However, there are no reliable estimates of abundance. Berzin et al. (1990) believed the individuals in the southwest Okhotsk Sea to number at least 250–300 animals, while Vladimirov (1994) estimated the subpopulation at 300–400 whales for the entire Okhotsk Sea. These values appear to be based primarily on the numbers seen, without evaluation of effective search effort. The proportion of the subpopulation that comprises mature animals is unknown. A value of 44% has been estimated for the Bering-Chukchi-Beaufort Sea stock of bowhead whales. The absence of bowhead sightings on any of the Japanese-Russian systematic surveys of cetaceans in the Okhotsk Sea (referred to above) tends to suggest that the subpopulation is small.
The subpopulation was subject to intensive commercial whaling during the short period 1852–1860 and apparently had been depleted by 1860, although some catching continued until 1900. Woodby and Botkin (1993) estimated a minimum initial subpopulation size of about 3,000 based on catch records. In the late 1960s, Soviet ship-based whalers took an unknown number of bowheads in the Okhotsk Sea illegally (Doroshenko 1996). The subpopulation thus appears to still be at a small fraction of its pre-whaling abundance, and there is no direct information to assess whether or not the subpopulation is increasing.
|Current Population Trend:||Unknown|
|Habitat and Ecology:||Little is known about the specific ecology of the Okhotsk Sea Bowhead Whale subpopulation. Unlike other Bowhead Whale subpopulations, this one inhabits an area that is ice-free in summer.|
The seasonal distribution of Bowhead Whales in general is strongly influenced by pack ice (Moore and Reeves 1993). During the winter bowhead whales occur in areas near the ice edge, in polynyas, and in areas of unconsolidated pack ice. During the spring these whales use leads and cracks in the ice to penetrate areas that were inaccessible during the winter due to heavy ice coverage. During the summer and autumn they concentrate in areas where zooplankton production is high or where large-scale biophysical processes create local concentrations of calanoid copepods (Finley 1990, Finley et al. 1998).
Small to medium-sized crustaceans, especially krill and copepods, form the bulk of the bowhead's diet (Lowry et al. 2004). They also feed on mysids and gammarid amphipods, and the diet includes at least 60 species. Bowheads skim feed at the surface and feed in the water column. It has recently been suggested that they also feed near the bottom, but probably do not directly ingest sediments as Gray Whales routinely do.
|Movement patterns:||Full Migrant|
|Major Threat(s):||This population is not currently subject to hunting. At least one case of fatal entrapment of an Okhotsk Sea Bowhead Whale in fishing gear has been documented (Brownell 1999).|
The International Whaling Commission has protected Bowhead Whales from commercial whaling since its inception in 1946 and there is no aboriginal subsistence whaling exemption for Okhotsk Sea Bowhead Whales. The species, including this population, is protected under Russian law through its inclusion on the Russian national Red List. This species has been included in CITES Appendix I since 1975. The species listed in Appendix I of CMS.
|Citation:||Reilly, S.B., Bannister, J.L., Best, P.B., Brown, M., Brownell Jr., R.L., Butterworth, D.S., Clapham, P.J., Cooke, J., Donovan, G., Urbán, J. & Zerbini, A.N. 2012. Balaena mysticetus (Okhotsk Sea subpopulation). The IUCN Red List of Threatened Species 2012: e.T2469A17879585.Downloaded on 23 April 2018.|
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