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Gray Whale
Eschrichtius robustus
Over two decades ago,
the West Coast Whale Research (now Pacific WildLife Foundation)
pioneered studies of the gray whales off Vancouver Island, and thanks to
donor support the studies continue.
The coastal dwelling
gray whale is the most often encountered whale on the Pacific Coast of
North America and the object of a flourishing whale-watching industry.
Gray whales are distinctive from other whales by the combination of
medium size (for a whale: 10-15m), mottled gray skin pigmentation,
absence of a dorsal fin, and propensity to come very close to shore.
The eastern Pacific
population, sometimes referred to as the California stock, calves off
the coast of Baja California and most individuals spend the summer
feeding in the Bering and Chukchi Seas. Small numbers spend the summer
feeding off southeast Alaska, British Columbia, Washington, Oregon and
California. The eastern Pacific population is thought to be about 20,000
individuals, down somewhat from estimates of few years ago of up to
26.000.
Some scientists suggest
the population has reached its capacity, noting that large numbers of
strandings in recent years may have been the result of starvation. The
average of 41
stranded gray whales reported between 1995 and 1998, was followed by a
large increase to 283 strandings in 1999 and 368 in 2000. However, the
number of strandings fell to 21 in 2001 and 26 in 2002. Researchers
concluded that no clear explanation could be derived for the stranded
whales but that a common, wide ranging factor was likely involved and
that starvation was most likely (Gulland et al 2005).
The western Pacific
gray whale population sometimes referred to as the Korean stock, is
composed of just 100 animals and is considered critically endangered.
Western gray whales spend the summer feeding near Sakhalin Island. Their
breeding ground is unknown but suspected to be in the waters off
southern China.
References
Baird, R.W., P.J. Stacey, D.A. Duffus and K.M. Langelier. 2002. An
evaluation of gray whale (Eschrichtius
robustus) mortality incidental to fishing operations in
British Columbia, Canada. Journal of Cetacean Research and Management
4:289-296.
Bowen, W. D. and D. B. Siniff. 1999. Distribution,
population biology and feeding ecology of marine mammals. Pp. 423-484 in
Reynolds, J. E., III and S. A. Rommel (eds.). Biology of marine
mammals. Smithsonian Institution, Washington DC
Breiwick, J. W. 1999.
Gray whale abundance estimates, Pp. 62 in D. J. Rugh, M. M. Muto, S. E.
Moore and D. P. DeMaster. Status review of the eastern north pacific
stock of gray whales. US Department of Commerce. NOAA Tech Rep. Memo
NMFS-AFSC-103, Washington, D.C.
Darling, J.D. 1984. Gray whales off Vancouver Island, British Columbia.
Pp. 276 – 287 in The Gray Whale.
M. L. Jones, S.
Swartz and S. Leatherwood (eds.). Academic Press, New York, NY.
Darling, J.D., Keogh,
K.E., and T.E. Steeves. 1998. Gray whale (Eschrichtius robustus) habitat
utilization and prey species off Vancouver Island, B.C. Marine Mammal
Science 14, 692-720.
Gulland, F.M.D. and
others.
2005. Eastern North Pacific gray whale (Eschrictius
robustus) unusual mortality event,
1999-2000. NOAA Technical Memorandum NMFS-AFSC-150.
Rice, D. W. and A.
A. Wolman. 1971. The life history and ecology of the gray whale
Eschrichtius robustus. American Society of Mammalogists, Special
Publication 3, 142 p.
Wartzok, D. and D. R. Ketten. 1999. Marine mammals sensory systems. Pp.
117-175 in Reynolds, J. E., III and S. A. Rommel (eds.). Biology of
marine mammals. Smithsonian Institution, Washington DC
Wilson, D. E. and S. Ruff. 1999. The Smithsonian book of
North American mammals. Smithsonian Institution, Washington, D.C.
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