The phrase "elephant populations" refers to the total number of elephants living in a certain area or region. It is a way to describe how many elephants there are in a particular group or location. Full definition
The African elephant population is a quarter to a half the size it was in 1979, greatly affecting ecosystems and the tourism industry. (sciencemag.org)
The illegal ivory trade threatens the persistence of stable wild elephant populations. (science.sciencemag.org)
The Asian elephant population, estimated at fewer than 50,000 internationally, is highly endangered. (ivghospitals.com)