Hasler, Arthur Davis

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(b. Lehi, Utah, 5 January 1908; d. Madison, Wisconsin, 23 March 2001),

fish physiology, limnology.

Hasler was head of the Wisconsin limnological school for about four decades, and he oriented it toward experimental research. He trained forty-one students for MS degrees and fifty-two for PhD degrees. His own research focused primarily on fish ecology, and his most famous discovery of how salmon find their home stream when they swim upriver to spawn was as important for salmon farming as it was for science. He authored or coauthored almost two hundred publications. He was president of three national and one international scientific organizations and received numerous honors for his scientific work.

Early Life . Hasler was the middle of five children born to Walter Thalman Hasler and Ada Elizabeth Broomhead Hasler. He grew up with a fondness for nature and fishing, but when he majored in zoology at Brigham Young University, it was in hopes of following his father into medicine. However, when he graduated in 1932, his father was ill and the country was in the Great Depression, and he could not afford to attend medical school. Instead, he went to the University of Wisconsin Graduate School to continue his zoological studies, since there he could work to defray his expenses. He gravitated to limnology, and he accepted dissertation advisor Chancey Juday’s suggestion that he conduct his research on the physiology of digestion in crustacean plankton. In the summer of 1935 he undertook research for the U.S. Fish and Wildlife Service on the effects of a pulp mill’s wastes on oysters in the lower York River, Virginia. He transferred sick oysters from that river into the nearby unpolluted Piankatank River and healthy oysters from the Piankatank into the York; undisturbed oysters in both rivers served as controls. He found that sick oysters recovered when moved to the Piankatank and that healthy oysters sickened when moved to the York. This was a harbinger of his later experimental approach to limnological research.

He married Hanna Prüsse Hasler (1908–1969) in 1932 and they had five sons and one daughter. In 1971 he married Hatheway Minton Brooks, who outlived him.

In 1937, after receiving his PhD, he accepted the Wisconsin Zoology Department’s invitation to become an instructor in zoology. Juday retired that year from teaching, but remained director of the Trout Lake Limnological Laboratory in northern Wisconsin until 1942. Hasler became assistant professor in 1941, associate professor with tenure in 1945, full professor in 1948, and professor emeritus in 1978. In the spring of 1945 Hasler, who was fluent in German, served as a research analyst with a U.S. Strategic Bombing Survey in Germany, and he took the opportunity to visit Karl von Frisch (who studied the behavior of fish as well as bees) at his Zoologisches Institut in Munich and Wilhelm G. Einsele at the Anstalt für Fischerei near Salzburg, Austria. Later, he reflected on these visits and decided to follow their examples and orient the Wisconsin limnological school toward experimentation and away from the traditional descriptive limnology practiced by Edward A. Birge and Chancey Juday. This decision coincided with a willingness of government to fund scientific research much more heavily than it had before World War II.

Olfactory Homing in Salmon . In summer 1946, Hasler returned to Utah on vacation and repeated two favorite pastimes of his youth—hiking the trails and fishing the streams of the Wasatch Mountains. As he climbed Mount Timpanogos, he wondered how salmon find their way back to their home stream to spawn. A cool breeze from a hidden waterfall brought the fragrance of mosses and columbine to him, and the image of the falls immediately came to his mind, along with childhood associations. If he had such a reaction to a remembered smell, perhaps salmon respond similarly.

Here was one line of research that he and several different graduate students pursued together for the rest of his career. It was a question in pure science, but with enormous practical applications, which made salmon farming practicable. He coauthored a cover story on some initial findings for the August 1955 issue of Scientific American. Fortuitously, while this research on salmon was underway, the Michigan Department of Natural Resources introduced Pacific salmon into Lake Michigan to eat the exotic alewife that had become a problem in the Great Lakes. The salmon did control the alewife, though neither species disappeared from the Great Lakes, and the Madison limnologists could then obtain their salmon for research close by. By the 1970s, there were as many as seven coauthors to some of the papers being published by the Madison group working on salmon homing in Lake Michigan.

Hasler synthesized their findings in two books. Underwater Guideposts (1966) is divided into three parts: (1) the hypothesis of olfactory location of the river mouth and the natal stream, with the supporting experiments; (2) the hypothesis of Sun orientation in open-sea migration and supporting evidence; and (3) the complete migration hypothesis, which emphasizes the sensory mechanisms and environmental cues. The second, a coauthored book, Olfactory Imprinting and Homing in Salmon(1983), delves more deeply into the physiology involved, including the hormones and biochemistry.

Other Research and Leadership . However, salmon migration was only one line of research Hasler and his students pursued. Other early experiments conducted by his students for doctoral dissertations concerned aquatic plant productivity (1947), minnow productivity (1949), and the introduction of hydrated lime into dystrophic lakes (1954, 1958) (Hasler, 1963). In 1953–1954 Hasler and his family moved to Munich on a Fulbright Research Scholarship to study fish sensory abilities with von Frisch. In Munich he found that the European minnow could orient itself toward a lamp (simulating the Sun) in the laboratory to obtain food, while other environmental factors varied randomly. After returning to Madison he wondered if Sun-compass orientation could be demonstrated in fish in both laboratory and in natural environments. He persuaded several doctoral and postdoctoral students to investigate several aspects of this question. Salmon are guided by smell when they swim up their home stream, but they spend up to five years at sea. How do they locate the river up which they swim? A whole different set of experiments demonstrated that Sun-compass navigation is used to find the right river.

As busy as Hasler was doing research and guiding that of his students, he also found time for professional activities. He was able to hire research managers, paid out of research grants, to help his students and free some of his time for other matters. The Limnological Society of America was founded in 1936, and in 1948 it expanded to become the American Society of Limnology and Oceanography. Hasler was its president in 1951. In 1961 he brought in an associate professor from Montana, John C. Wright, to help organize the Fifteenth Congress of the International Association of Limnology—the first one in the United States. Under his chairmanship, it was held in Wisconsin in 1962, and it inspired the encyclopedic volume Limnology in North America (Hasler, 1963), written by thirty-two collaborators. Hasler also served as president of the Ecological Society of America in 1961, the American Society of Zoologists in 1971, and the International Association for Ecology, 1967–1974, and presided at the First Congress of the latter association at The Hague in 1974. His achievements also led to memberships in prestigious societies. He was elected a fellow of the Philadelphia Academy of Sciences in 1953, the American Institute of Fisheries Research Biology in 1958, the American Association for the Advancement of Science in 1960, the Animal Behavior Society in 1967, and a member of the National Academy of Sciences in 1969 and the Royal Netherlands Academy of Sciences in 1976.

In 1937, Hasler had for his use only a small two-room laboratory on the shore of Lake Mendota, the lake adjacent to the university campus. As the limnological school grew under Hasler, its needs could not be fully met by the Department of Zoology’s budget. In 1962 Hasler obtained from the National Science Foundation funds to build a new Laboratory of Limnology. Hasler chose the location on the shore of Lake Mendota, within the university campus. He also chose the architect, and worked with him in designing the building. Since 1998 it has been enclosed by the Arthur Davis Hasler Lake Laboratory Garden, and in 2006 the laboratory was renamed the Arthur Davis Hasler Laboratory of Limnology. Hasler was its head from the opening in 1963 until his retirement in 1978. The Wisconsin limnological school under Birge and Juday lasted for forty years, and under Hasler for another forty years. They made Lake Mendota the most widely studied lake in the world.


Hasler authored or coauthored almost two hundred publications.


“Wisconsin, 1940–1961.” In Limnology in North America, edited by David G. Frey. Madison: University of Wisconsin Press, 1963. Hasler describes the Wisconsin limnological school under his guidance during the first two decades.

Underwater Guideposts: Homing of Salmon. Madison: University of Wisconsin Press, 1966.

With Allan T. Scholz and Robert W. Goy. Olfactory Imprinting and Homing in Salmon: Investigations into the Mechanism of the Imprinting Process. New York: Springer-Verlag, 1983.


Beckel, Annamarie L., and Frank N. Egerton, eds. “Breaking New Waters: A Century of Limnology at the University of Wisconsin.” Special issue, Transactions of the WisconsinAcademy of Sciences, Arts, and Letters (1983). Describes Hasler’s career.

Likens, Gene E. “Arthur Davis Hasler, January 5, 1908–March 23, 2001.” Biographical Memoirs, vol. 82. Washington, DC: National Academy of Sciences, 2002. Available from http://fermat.nap.edu/html/biomems/. Likens was one of Hasler’s doctoral students.

Frank N. Egerton