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Gray whale (Eschrichtius robustus) migratory movements between the western North Pacific and the Mexican breeding grounds: 2022 Update
S. Mart?nez-Aguilar, J. Urb?n R., D. Weller , O. Tyurneva. A. Bradford, A. Burdin, A. Lang, S. Swartz, O. Sychenko, L. Viloria-G?mora, E. Hern?ndez and Y. Yakovlev
While gray whales (Eschrichtius robustus) have traditionally been considered to be separated in two populations, one in the western North Pacific (WNP) and the other in the eastern North Pacific (ENP), we provide recent sightings of WNP gray whale in Baja California, Mexico during the winter breeding season. Historical evidence indicates that the South China Sea may have been used as a wintering ground in the WNP while for ENP the Baja California Peninsula, Mexico is the main breeding and calving area during the winter. In recent years ,? research including: photo-identification, telemetry and genetics has shown some degree of mixing between populations. Here, we present an update from a multinational effort to show the movements of gray whales identified in WNP feeding grounds and ENP breeding ground in Mexico. Images of 378 whales identified on the summer feeding grounds off Russia (229 from Sakhalin; 63 from Kamchatka and 86 registered in both areas), were compared to 11,000 individuals (right flank photo-ID images) ?photographed in the wintering lagoons of Baja California, Mexico (1540 from Laguna Ojo de Liebre; 5857 from Laguna San Ignacio; and 3603 from Bahia Magdalena). A total of 48 matches of WNP and ENP gray whales were found, including 21 females, 14 males, and 13 whales of unknown sex: matches included 13Sakhalin/Kamchatka-Mexico, 28 Sakhalin-Mexico, and 7 Kamchatka-Mexico. Movements between the WNP and ENP represents 12.6% of gray whales identified off Sakhalin Island and Kamchatka, and the 0.4% of the gray whales identified in the breeding lagoons of Baja California peninsula Mexico. From the 48 gray whales that have migrated between WNP and Mexico, 16 of them have migrate to Mexico at least twice in different years (range from 2 to 5 migrations).