Arthur Davis Hasler (January 5, 1908 – March 23, 2001) was an ecologist who is credited with explaining the salmon's homing instinct.^[1][2][3][4] Hasler was a member of the National Academy of Sciences and the American Academy of Arts and Sciences.^[2] The New York Times called him "an internationally recognized authority on freshwater ecology".^[2] He served as President of The Ecological Society of America,^[3] which called him "one of the leading figures in 20th century freshwater ecology".^[3] Hasler pioneered a research method based on manipulation of entire lake ecosystems. This method became an instrumental new tool for ecology.^[4] He published over 200 scientific papers, was an author or an editor of 7 books, and supervisor of 52 doctoral degrees.^[5]

Hasler was born in Lehi, Utah.^[1] He married Hanna Prusse in 1932, and they had six children: Sylvia, A. Frederick, Bruce, Galen, Mark, and Karl.^[4] He graduated from Brigham Young University in 1932.^[1] He received a doctorate in zoology from the University of Wisconsin–Madison in 1937.^[1][4] Hasler was an analyst with the Air Force Strategic Bombing Survey based in Germany after World War II.^[1][2] Hasler was a Fulbright scholar at the Max Planck Institute in Germany from 1954 to 1955.^[5] Subsequently, Hasler was on the faculty of the University of Wisconsin–Madison for 41 years and under his leadership it became a hub for lake research.^[2] In 1961 he served as President of The Ecological Society of America.^[3] He headed the Limnology Laboratory at the University of Wisconsin–Madison from 1963 to 1968.^[6] In 1969 he was elected to the National Academy of Sciences.^[5]