Gone for the winter: Finding the lost North Pacific right whale (Eubalaena japonica) calving grounds

Despite decades of protection, the North Pacific right whale (Eubalaena japonica) remains critically endangered and the location of the whales’ calving habitat remains unknown. We set out to identify the location of these... [ view full abstract ]

Despite decades of protection, the North Pacific right whale (Eubalaena japonica) remains critically endangered and the location of the whales’ calving habitat remains unknown. We set out to identify the location of these winter calving grounds in the western North Pacific based on the habitat preferences of right whales calving in the Atlantic Ocean. We employed a previously developed log likelihood habitat model based on habitat conditions associated with right whale calf observations. Our evaluation focused on three habitat parameters: water depth, sea surface temperature and surface roughness. The model demonstrated that right whales prefer calving habitat that is characterized by shallow (mean 15.23m ± 0.19), cold (14.21°C ± 0.07) and calm waters (-25.04db ± 0.08). Application of this model to the eastern North Pacific region yielded potential calving habitat along the coast of China and northern coast of Vietnam. The most robust habitat identified by the model occurred along coastal areas in the northern Gulf of Tonkin and to a lesser extent off Fujian Province in China. This region offered winter habitat that was consistent with the shallow, cold and calm waters preferred by right whales in other parts of the world. Limited historic records from these regions suggest right whales were once present, but additional aerial, shipboard or acoustic surveys are needed to verify if right whales currently use these areas for calving in winter.