the horn (waldhorn) for some 30 years in the University of Wisconsin Symphony and the Madison Civic Symphony. He frequently greeted a woman with a kiss to her hand. On long road trips to research sites and scientific meetings it was not uncommon for Hanna to break out the songbooks, pass them out in the car, and lead everyone in singing. In those days a major professor and graduate students often took long trips together by car to field sites and professional meetings. Hanna died in 1969. In 1971 Hasler married Hatheway Minton Brooks, who shared his love for a healthy environment, and with her own six children forged a close and loving extended family. Hasler had 32 grandchildren and 17 great-grandchildren.
He received a B.A. degree, majoring in zoology, from Brigham Young University in 1932 and a Ph.D. degree in zoology and physiology from the University of Wisconsin-Madison in 1937. He was awarded honorary doctor of science degrees from the Memorial University of Newfoundland in 1967 and Miami University, Oxford, Ohio, in 1988.
Hasler had interrupted his schooling at Brigham Young University in the late 1920s to serve a three-year mission to Germany for the Church of Jesus Christ of Latter Day Saints. It was during this time that his love for the German language began.
After working for the U.S. Fish and Wildlife Service as an aquatic biologist on the Chesapeake Bay during 1935–37, he and Hanna moved to Madison where he completed his Ph.D. in 1937 at the University of Wisconsin, under the supervision of well-known limnologist Chancey Juday. He was hired there as an instructor of zoology in 1937 and promoted to assistant professor in 1941. After serving with the U.S. Strategic Bombing Survey in Germany in 1945, he returned to the university in 1945 as associate professor of zoology and was promoted to full professor in 1948, and