The Shiho and Naisa forms are actually subspecies of the short-finned pilot whale, with the Shiho clade having diverged approximately 17.5 thousand years ago (kya), during the last glacial maximum. The exact boundaries of the two subspecies’ ranges remain undefined due to lack of data. Based on current evidence, the Shiho subspecies is distributed in the eastern Pacific Ocean, and the Naisa subspecies encompasses the central/western Pacific and Indian Oceans, as well as the Atlantic Ocean. It appears as though the Pacific Ocean acts as a semi‐permeable barrier between the two subspecies, allowing occasional migration and mixing between the eastern and western Pacific Ocean, but keeping the populations separate enough to drive this differentiation.