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Home Biology Ecology. Credit: CC0 Public Domain. Citation : Gray whale population drops by quarter off U. Winter the dolphin was born off the coast of Florida in where it was WDC welcomes the news from online travel company Expedia Groups that they've updated their animal Ramari Steward and nihongore skeleton Credit: Tanya Cumberland New species of whale includes "traditional" naming Load More.
All policy news. Feb Whale culture should play a part in their conservation says new international study By George Berry. An international group of researchers working on a wide range of species, including whales, argues No change in Norway whaling quota as number of whales to be killed remains high By Regina Asmutis-silvia.
Mar After passing Nunivak Island, they head toward St. Lawrence Island, arriving there in May or June. The whales disperse to spend the summer feeding in shallow waters usually less than feet 60 m deep of the northern and western Bering Sea and the Chukchi Sea. Gray whales begin their southward migration in mid-October, passing through Unimak Pass between late October and early January, arriving in Baja California, Mexico in December and January.
Throughout the winter of —, gray whale calls were recorded in deep waters near Barrow, Alaska. Researchers attributed their presence in summer feeding grounds during that particular winter to a combination of the increasing population size, habitat alteration associated with sea ice reduction, and warming in the Alaskan arctic.
At one time there were three gray whale populations: a north Atlantic population, now extinct; a Korean or western Pacific stock now very depleted; and the eastern Pacific population, the largest surviving population. The north Atlantic stock is thought to have become extinct in the 17th century. In the north Pacific, gray whales had been hunted to the edge of extinction in the 's after the discovery of the calving lagoons, and again in the early 's with the introduction of floating factories.
The gray whale was given partial protection in , and full protection in by the International Whaling Commission. Since that time the eastern north Pacific gray whale population has made a remarkable recovery and now numbers approximately 26,, probably close to their original population size. The western Pacific stock was listed as endangered under the Endangered Species Conservation Act of and currently is estimated to contain only individuals.
The eastern Pacific stock was originally included in this listing, but was removed in Both stocks are listed as depleted under the Marine Mammal Protection Act of The only major predators of gray whales are killer whales and humans. Many gray whales have healed scars and killer whale teeth marks on their flukes and flippers. Early whalers and Eskimos from coastal Alaskan villages have reported many instances of gray whales fleeing into very shallow water and sometimes beaching or stranding themselves while trying to escape pursuing killer whales.
During and a disproportionately large number of gray whales stranded along the west coast of North America; factors causing these events were not determined. Most of the whales spend the summer feeding in the Arctic. A western North Pacific population of gray whales, which summers off the Russian coast in the Okhotsk Sea, remains endangered with only around individuals.
Gray whales provide a unique opportunity to study a population of large whales that has recovered from near extinction. Because many other large whales are still threatened or endangered, scientists have had few opportunities to observe how the dynamics of a recovered population abundance, reproduction, and survival fluctuate in relation to the environment.
Gray whales serve as ecosystem sentinels, alerting us to possible changes in the environment. The Arctic, where the primary feeding areas for gray whales are located, is changing rapidly. Reductions in the distribution of Arctic sea ice may affect the distribution and abundance of gray whale prey, for instance.
Although gray whales in the eastern North Pacific have recovered from low numbers caused by past commercial whaling, the whales continue to face an array of modern threats.
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