Status of Pacific sperm whale stocks before modern whaling

Catch profiles of the hunt for Physeter macrocephalus in two areas of the Pacific were estimated for 1800-1930. Sighting rates obtained from logbooks of whalers operating at the height of the hunt, and the estimates of population parameters contained in the IWC's Sperm Whale Model, allow population trajectories to be constructed for these areas during the interval between the beginning of open-boat whaling (1790) and when modern whaling started in earnest (1946). Sperm whale populations near the Galapagos Islands and in the W North Pacific were 10-30% of their pre-whaling sizes in 1946. Levels of depletion for these two areas in 1946 may be higher than these estimates on account of modern whaling during the first half of the 20th century. -from Author