title: Critically endangered western gray whales migrate to the eastern North Pacific.
abstract: Western North Pacific gray whales (WGWs), once considered extinct, are critically endangered with unknown migratory routes and reproductive areas. We attached satellite-monitored tags to seven WGWs on their primary feeding ground off Sakhalin Island, Russia, three of which subsequently migrated to regions occupied by non-endangered eastern gray whales (EGWs). A female with the longest-lasting tag visited all three major EGW reproductive areas off Baja California, Mexico, before returning to Sakhalin Island the following spring. Her 22 511 km round-trip is the longest documented mammal migration and strongly suggests that some presumed WGWs are actually EGWs foraging in areas historically attributed to WGWs. The observed migration routes provide evidence of navigational skills across open water that break the near-shore north-south migratory paradigm of EGWs. Despite evidence of genetic differentiation, these tagging data indicate that the population identity of whales off Sakhalin Island needs further evaluation.
authors: Marine Mammal Institute, Department of Fisheries and Wildlife, Oregon State University, Hatfield Marine Science Center, Newport, OR 97365, USA.
authors: Bruce R
authors: BR
authors: Mate
authors: Institute of Ecology and Evolution of the Russian Academy of Science, Moscow 119071, Russia.
authors: Valentin Yu
authors: VY
authors: Ilyashenko
authors: School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington DC 98195-5020, USA.
authors: Amanda L
authors: AL
authors: Bradford
authors: Kronotsky State Nature Biosphere Reserve, Elizovo, Kamchatka 684010, Russia.
authors: Vladimir V
authors: VV
authors: Vertyankin
authors: Institute of Ecology and Evolution of the Russian Academy of Science, Moscow 119071, Russia.
authors: Grigory A
authors: GA
authors: Tsidulko
authors: Institute of Ecology and Evolution of the Russian Academy of Science, Moscow 119071, Russia.
authors: Vyacheslav V
authors: VV
authors: Rozhnov
authors: Marine Mammal Institute, Department of Fisheries and Wildlife, Oregon State University, Hatfield Marine Science Center, Newport, OR 97365, USA ladd.irvine@oregonstate.edu.
authors: Ladd M
authors: http://orcid.org/0000-0001-5135-3496
authors: LM
authors: Irvine
mesh_terms: D025041:Animal Migration; D000818:Animals; D056727:Endangered Species; D005260:Female; D008297:Male; D010140:Pacific Ocean; D012621:Seasons; D014907:Whales / Q000502:physiology*
keywords: endangered species; migration; satellite tracking; stock structure; western gray whale; wide-ranging species