Arthur D Hasler Biographies
1) Biographical Sketch by A.T. Scholz in Fishes of Eastern Washington
2) Gene Likens biography of Arthur D Hasler
Copied from A.T. Scholz Fishes of Eastern Washington: A Natural History pages 134-137
Arthur Davis Hasler (1908–2001)
Arthur D. Hasler (Figure 3.36) was born in Utah and graduated from Brigham Young University with a Bachelor’s degree in 1932. He completed his doctoral degree at the University of Wisconsin under the supervision of Chancey Juday in 1937, where he also interacted with E. A. Birge. He was hired as an instructor of Zoology at Wisconsin in 1937 and was promoted to assistant professor in 1941, associate professor in 1945, and full professor in 1948. During his 41 years on the faculty at the University of Wisconsin, Hasler authored more than 200 papers and 7 books, and supervised 52 doctoral students, and 43 master’s students (Likens 2003).
Hasler realized that lakes go through stages, gradually becoming more eutrophic as they age. He found that the land-water interactions were a primary variable that affected this aging process and hence the water quality and ecological health of lakes. When he applied this thinking to Lake Mendota, Wisconsin, he recognized that fertilizer runoff and soil erosion from agriculture lands along the Yahara River, the lakes inlet, were accelerating the rate of aging Lake Mendota.
The increased nutrient loading of the lake from human activity on the land upstream from the lake was increasing algal production and creating unsightly (and stinky) algae blooms in the lake. Hasler called this “cultural” eutrophication and realized that the way to reduce it would be for county or state governments to enact laws that would regulate the amount of nutrients that could be discharged into the water (Hasler 1947).
Hasler is credited with ushering in a new era of “experimental Limnology”. Not content with merely describing the characteristics of lake like his predecessors, Birge and Juday, he pioneered a new way to study lakes by conducting “whole lake manipulations.” The most famous experiment took place in Peter and Paul lakes in Michigan’s upper peninsula. Peter and Paul lakes where dystrophic, brown stained, acid bog lakes shaped like an hourglass. Hasler received permission to bulldoze an earthen dam across the narrow constriction between these two lakes in 1951. Subsequently one lake (Peter) was treated with hydrated lime to flocculate and precipitate dissolved organic carbon, while the other (Paul) was maintained as an untreated reference (control). Hasler and his students then measured the effects of this manipulation by making physical/chemical comparisons and measuring the effects of the biota of both the experimental and reference lake (Johnson and Hasler 1954; Hasler 1964). For example, improved water clarity increased phytoplankton and zooplankton production, which provided more food for rainbow trout, thereby increasing trout production in the experimental lake.
Hasler served with the U.S. Strategic Bombing Survey in Germany in 1945. There he met German Nobel Laureates Konrad Lorenz and Karl von Frisch, who inspired Hasler in the research he is best known for on olfactory imprinting and homing in salmon.
Von Frisch had been studying the Schreckstoff reaction in minnows. Schreckstoff is an alarm pheromone that is released when the skin of a minnow is broken, for example by a fish eating bird swooping down and grabbing one in its talons. It signals other minnows in the school of danger, causing the school to rapidly disperse. The lesson Hasler took back from his discussion with von Frisch was that some species of fishes had a very acute sense of smell.
Lorenz had been investigating imprinting in geese. Imprinting refers to the permanent bond that forms between a gosling and its mother. For many years it was thought that this bond resulted from genetics. Instead, Lorenz showed that imprinting is learned rather than genetic. Imprinting is a process of rapid irreversible learning during a critical period that elicits a stereotyped pattern of behavior. In geese, the critical period occurs shortly after hatching, when the gosling forms a permanent attachment to the first moving object it sees—normally its mother waddling in front of it. Lorenz proved his thesis by assuming the role of a surrogate mother. He paced in front of a group of eggs as they were hatching; the goslings forsook their avian ancestry and adopted Lorenz as their mother. The birds followed him around like a shadow everywhere he went, just as goslings follow their mother. The lesson Hasler took back from his discussions with Lorenz was that an animal could be imprinted in a narrow window of time (called the “critical period” in its development) and form a permanent memory of whatever it was imprinted to.
It was during a vacation to Utah that an incident occurred that caused Hasler to incorporate the imprinting concept with the problem of homing in salmon. “We had driven across the sage country and high desert from Madison, Wisconsin to my parental home in Provo, Utah . As I hiked along a mountain trail in the Wasatch Range of the Rocky Mountains where I grew up, my reflections were interrupted by wonderful scents that I had not smelled since I was a boy. Climbing up toward the alpine zone of Mt. Timpanogos, I had approached a waterfall which was completely obstructed from view by a cliff; yet, when a cool breeze bearing the fragrance of mosses and columbine swept around the rocky abutment, the details of the waterfall and its setting in the face of the mountain suddenly leapt into my mind’s eye. In fact, so impressive was this odor that it evoked a flood of memories of boyhood chums and deeds long since vanished from conscious memory. The association was so strong that I immediately applied it to the problem of salmon homing. The connection caused me to formulate the hypothesis that each stream contains a particular bouquet of fragrances to which salmon become imprinted before emigrating to the ocean, and which they subsequently use as a cue for identifying their natal tributary upon their return from the sea. I envisioned that the soil and vegetation of each drainage basin would impart a distinctive odor to the water, thereby providing the salmon with a unique cue for homing” (A. D. Hasler, in Hasler and Scholz 1983).
Hasler was also aware of studies that showed if salmon were removed from their natal tributary and transplanted to different one, where they smolted and migrated to the sea, they would return to the transplant stream rather than the natal tributary. This immediately suggested to Hasler that homing was not connected to a genetic memory of the home stream. Rather, the data implied that salmon learn (or imprint to) the cues that identify their “home stream” during a critical period of development, the smolt stage. The smolt stage is when salmon turn silver, develop osmoregulatory correctional mechanisms that enable them to survive in seawater, and migrate, en masse, to the ocean. In 1951, Hasler formalized this hypothesis in collaboration with his graduate student Warren J. Wisby (Hasler and Wisby 1951).
The olfactory hypothesis for salmon homing presented by Hasler and Wisby (1951) was broken into three testable hypotheses:
1. Each stream has a distinctive odor that is detectable by fish;
2. Juvenile salmon become imprinted to the distinctive odor of their home tributary during the smolt stage, the critical period for imprinting; and
3. Adult salmon use this odor information stored in long term olfactory memory, to find their home stream during the spawning migration.
Hasler and Wisby (1951) (Figure 3.37) and Wisby (1952) used classical conditioning experiments to determine if fish could discriminate two different streams, one running through an open meadow, the other through forested land. They used groups of blunt nose minnows and Coho salmon for these tests. One group of fish was given a food reward shortly after water from the meadow stream was added to their tank (positive reinforcement) and mild electroshock shortly after water from the forested stream was added to the tank (negative reinforcement). These fish learned to associate these types of water being added with either the food reward or electroshock punishment because after about 40 trials they clustered underneath the feeder before any food was added whenever water from the meadow stream added to their tank, or cowered at the opposite end of the tank (away from the shock electrode) whenever water from the forested stream was added and before the electroshock was administered.
When their nasal sacs were occluded or cauterized, fish that had been previously trained were no longer able to discriminate between the two waters. If their nasal sacs were occluded or cauterized before training began, they were not able to learn to associate the food reward or the electroshock punishment with either stream. Thus, Hasler and Wisby (1951) had demonstrated that each stream has a characteristic odor that is detectable by fish.
Next Hasler and Wisby devised a field experiment to test the olfactory hypothesis. Their research site was a small Y-shaped tributary located 25 km from Seattle, Washington: Issaquah Creek and its East Fork. Each branch had its own native stock of Coho salmon. Hasler and Wisby set up weirs in both streams to collect salmon. The nasal chamber of half the fish from each tributary was plugged with Vaseline coated cotton, while the remaining fish were left unplugged to control for olfactory impairment. Each fish was tagged so that it could be identified in terms of the treatment it had received and the branch where it was originally caught. All of the fish were then released 1.6 km below the junction of the two streams and allowed to repeat their upstream migration. Almost all of the control fish released migrated upstream into the same trap where they were originally collected. In contrast, only about half of the fish deprived of their sense of smell migrated upstream and those that did were distributed randomly between the two traps. Sensory impairment experiments were criticized by Brett and Groot (1963), Harden-Jones (1968), Peters (1971) and Ramsey (1961), who argued that nose-plugged fish may home with less precision because of generalized traumatic or inhibitory effects rather than because of loss of the olfactory sense. Consequently, the results of sensory-impairment experiments are difficult to interpret. Another problem with the ablation experiment was that the fish had been exposed to their home water shortly before being tested, so the homing behavior exhibited during the experiment may be owing to “short term conditioning” rather than long-term memory of the stream.
These criticisms condense to a central point: to determine if olfactory imprinting occurs, a definitive experiment must encompass two periods in the life of the salmon, the smolt stage, when imprinting takes place, and the adult spawning migration, when the fish must use their “long-term olfactory memory” of the natal tributary as a cue for homing. To take both periods into account, Hasler and Wisby (1951) proposed to imprint smolting salmon artificially with synthetic chemicals as a substitute for natural stream odors, and later, to use the scent to attract the fish into a different tributary. The proposed method eliminated recent experience as a factor and allowed them to manipulate olfactory cues without interfering with the fish’s olfactory sense, so that problems with sensory impairment could be avoided.
The author of this book (Allan T. Schmolz) was Hasler’s last graduate student and collaborated with him in performing this experiment. Working at a fish hatchery in the Mississippi River drainage of Wisconsin, we exposed one group of 18-month-old Coho salmon to a synthetic chemical called morpholine and a second group to a different synthetic chemical called phenethyl alcohol for about 30 days during the smolt stage. A third group was left unexposed (control). Each fish was given a distinctive fin clip, which corresponded to the treatment odor it had received.
At the end of the exposure period, all three groups were trucked to Lake Michigan and released midway between the two test streams, the Little Manitowoc River and Two Rivers, located 9.4 km apart.
During the spawning migration, morpholine was metered into one of the test streams (Little Manitowoc River) and phenethyl alcohol into the other (Two Rivers). The streams were surveyed for marked fish by conducting electro fishing, gill netting and creel surveys. In addition, 17 other locations were also monitored to determine whether a significant number of experimental fish were straying into non-scented streams.
This experiment was conducted twice – this artificial imprinting was done in 1973 with 5,000 fish in each group and again in 1974 with 10,000 fish per group. The spawning migrations of three-year-old fish were in 1974 and 1975 respectively. The data from both experiments showed that of the morpholine exposed fish recovered, 95% were captured in the morpholine-scented stream; and, of the phenethyl alcohol exposed fish 92.5% were captured in the phenethyl-alcohol-scented stream. By contrast, large numbers of control fish were captured at other locations. About twice as many fish were recovered from each group in 1975 (from the release of 10,000 smolts per group in 1974) than in 1974 (from the release of 5,000 smolts per group in 1973) (Scholz et al. 1976; Hasler et al. 1978; Hasler and Scholz 1983).
Our procedure gave some assurance that the fish did not learn alternative cues about the test streams, since they had been reared in a hatchery whose waters flowed into the Mississippi River and were stocked directly into Lake Michigan. Hence, we inferred that they were returning to the test streams because of the odor they had been exposed to as smolts. Our results demonstrated that olfactory imprinting occurs when the fish are 18 months old at the time they undergo the transition from parr to smolt. They retained an odor memory of these synthetic chemicals without again being exposed to them for the 1.5 years they were at large in Lake Michigan, and, as adults, returned to the synthetic chemical that they had been exposed to as smolts.
Hasler was elected to the National Academy of Sciences in 1969. He received an Award of Excellence from the American Fisheries Society (AFS) in 1977 and the Distinguished Service Award from the American Institute of Biological Sciences (AIBS) in 1980. He was awarded the Navmann- Thienemann Medal from the International Association of Theoretical and Applied Limnology, the highest international award in Limnology, in 1992. He received about a dozen other prestigious awards.
Hasler served as president of the following professional societies: American Society of Limnology and Oceanography (1951), the Ecological Society of America (1961), the International Association for Ecology (1967–1974), and the American Society of Zoologists (1971). Hasler was also the founder and first director of the Institute for Ecology (1971–1974). According to John Magnuson, Hasler’s successor at the UW Limnology Lab, Hasler believed
“you were not done with your research until you dealt with the management implications it raised.... He loved music and poetry. He used to read poetry in his [Limnology] class about the beauty of lakes. He imparted a moral and ethical sense of the value and beauty of nature” (Carpenter and Kitchell, 2001).
He played the french horn for 30 years in the Madison Civic Symphony and the University of Wisconsin Symphony. When he retired in 1979, his former students held a festschrift in his honor. (Nearly all of the 52 PhD students he had directed and about 30 of his master’s students made it a point to be there; some flew to Madison from as far away as Hawaii or the East Coast to be there). They presented him with an original horn concerto that they had hired a composer to write.
Figure 3.37 (A) Operant conditioning apparatus used by Hasler and Wisby to test discrimination of stream odors by salmon. (B) Close up of apparatus showing Hasler on left
One of Hasler’s most memorable attributes was his store of German poems, which he could reel off (recite by heart) if given the slightest encouragement. For example, when a rock and flower garden at the UW Center for Limnology was dedicated to him in 1998, instead of giving a speech, he simply recited Eduard Mörike’s Septembermorgen:
Im Nebel ruhet noch die Welt,
Noch träumen Wald und Wiesen: Bald siehst Du, wenn der Schleier fällt, Den blauen Himmel unverstellt, Herbstkräftig die gedämpfte Welt
In warmem Golde fließen.
Following is a translation of September Morning by Walter A. Aue:
The world’s a dream in fog’s embrace,
Still slumber woods and meadows:
But soon, through the dissolving lace,
You’ll see the blue of endless space,
The milder grace of autumn’s face
Transcending golden shadows.
Gene Likens biography of Arthur D Hasler
ARTHUR DAVIS HASLER
January 5, 1908–March 23, 2001