Saturday 22 January 2011

Western gray whale tracked far to the east

A team of scientists from the Russian Academy of Sciences and Oregon State University Marine Mammal Institute has been tracking the movements of a rare and endangered western gray whale, tagged with a satellite transmitter in the north Pacific Ocean, off the west coast of Russia.

There are two genetically separate sub-populations of gray whale (Eschrichtius robustus), one on either side of the north Pacific, and it is believed that their ranges do not overlap. Gray whales once existed in the North Atlantic as well but were extinct by the early 1700s.

Both the eastern and western Pacific populations were severely depleted by commercial whaling during the 19th and 20th centuries. However, while the eastern gray has staged a remarkable recovery and now numbers around 20,000, the western population has not and is listed by the International Union for Conservation of Nature and Natural Resources (IUCN) as 'critically endangered'. The population is estimated to be lower than 140 individuals, including fewer than 40 reproductive females.

Perhaps the greatest threat faced by western gray whales is that their primary summer feeding area coincides with major offshore gas and oil exploration and mining in the Okhotsk Sea, within 20 km of Sakhalin Island. Intense human activity including seismic research, shipping, drilling and laying pipelines exposes this remnant population to risks from displacement, pollution, ship-strike and numerous sources of noise disturbance.

Tagged on 4 October 2010, the 13 year-old male gray whale travelled eastwards, transversing the Sea of Okhotsk until it encountered the Kamchatka Peninsula. From there it swam southwards and then northwards, skirting the peninsula. At around 55 degrees north latitude it struck out north-eastwards. At about 170 degrees west longitude, in mid-January, having journeyed most of the way across the Bering Sea, it turned sharply towards the south, in the general direction of the Pribilof Islands.

With its population so low and seriously at risk, information about the distribution and range of the western gray whale is of vital importance.

The satellite-tagged gray whale has now travelled some 5,000 kilometres and the unit is still in operation.

The whale's progress can be observed on the Oregon State University website at

(Image of LNG plant at Korsakov, Sakhalin Island ©Mark Cornish)


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