William Ricker Zoology, Animals, Physiology, Metabolism

Canada's Greatest Fisheries Biologist: Inventor of the Ricker Curve for describing fish population dynamics

"Try and arrange that you’re doing something that you’re interested in. There’s quite a bit of routine in research work but I’ve never worked on a project that I wasn’t very interested in."

The Story

Standing on a thin ledge of rock, just below Hell’s Gate rapids on the Fraser River in British Columbia, William Ricker dips his net into the eddy at his feet. He brings up a big sockeye salmon for tagging. This one is fresh and strong, not like the tired ones who are having trouble with the rapids. Again and again the weak ones find their way into his net. From a pocket, Ricker pulls out two little red and white metal discs and a five-centimetre pin. He wipes his brow and waves to his partner, who is tagging fish a few metres away. The sun is hot. A steady, hot wind blows up the narrow canyon. There is no road down to where they are, only a steep trail.

Ricker is 30. It is the summer of 1938, the first time he has worked on the big river, and he’s enjoying himself. It’s also the first year of the Canadian Salmon Commission’s study of Fraser sockeye. At the time, nobody really knew how or why salmon returned after years in the sea to mate and lay eggs in the very same creek where they were born.

While his partner holds down the lively fish, Ricker uses a pair of pliers to attach the bright tag through its body, just below the dorsal fin. Then he throws the wild sockeye back into the water to fight its way up the gorge through the roaring rapids. The team of four men catches and tags up to 20 fish per hour, several thousand in all — enough to accomplish the goal of the study, which is to find what fraction of the fish go to each of a dozen or so spawning grounds to mate and lay eggs at different seasons. Spawning grounds are the shallow creek beds where female salmon lay eggs, which male salmon then fertilize. Other fisheries scientists in those regions are on the lookout for the salmon and are making estimates of the numbers on each spawning ground.

By examining tags and counting fish, Ricker and his team are able, for the first time, to get an accurate picture of the Fraser River sockeye’s migration pattern.

As a young scientist...

When he was 11 years old, William Ricker began studying his dad’s star charts. His father was the science teacher at North Bay Normal School in North Bay, which is on Lake Nipissing in Ontario. Eventually Ricker could name all the constellations and the brightest stars. All through high school, in the springtime he would get up most mornings at five o’clock. For three hours before breakfast he would ride his bike into the woods or along the shore of Lake Nipissing, looking for birds. While he was at university, he used to get summer jobs at the Ontario Fisheries Research Laboratory, mainly working on trout in the Great Lakes.

After a job studying salmon life history

and enhancement at Cultus Lake, British Columbia, he became a professor of zoology at Indiana State University in Terre Haute, where from 1939 to 1950 he taught about birds and fish. Then he went back to Canada to work as editor of publications for the Fisheries Research Board of Canada in Ottawa, Ontario. In 1964 he moved to Nanaimo to become chief scientist of the Fisheries Research Board of Canada. From his retirement in 1973 until his death in 2001, he continued to work on a voluntary basis on the history of Fraser River salmon fisheries and on other projects.

During his life Ricker identified 90 new species of stoneflies, a major source of food for fish. He wrote a Russian/English dictionary of fisheries terms and was fluent in Russian. Toward the end of his life, he was working on a history book about early travel on the Fraser River canyon. He also had a keen interest in Sir Arthur Conan Doyle’s fictional detective Sherlock Holmes and even wrote a Sherlock Holmes mystery that was published in a Canadian Holmes anthology. As a railway buff he had an encyclopedic knowledge of North American routes of the past. Ricker was an accomplished musician and played bass viol in the Nanaimo Symphony Orchestra. He was interested in folk music of many types and often sang old cowboy songs, serenading his family around the fire on camping trips.

Curiously, Ricker was not a good fisherman, though he loved to fish and spent countless hours trolling the waters around Nanaimo and up and down the coastline of Vancouver Island — rarely catching anything.

The Science

Fisheries biology is the study of fish habitat and population. Knowing the number of spawners in a given year is crucial for predicting how many fish will be available for future harvest. Ricker knew salmon runs like some baseball fans know World Series statistics. He had kept track of the Canadian Salmon Commission’s estimates of the Fraser River sockeye ever since 1938.

Each year different numbers of salmon return to spawn, depending on the species. The five salmon species in British Columbia go through different cycles. For example, the big Fraser sockeye run of 2001 was the same “line” or “cycle” as the record run of 1913, which was around 100 million fish. For sockeye, such huge numbers occur only every four years. Other years are one-tenth as numerous or even less.

Ricker was the first scientist to suggest several possible reasons for the cyclic variation in returning salmon stocks. Biologists are still collecting evidence to determine the correct explanation. The Fraser sockeye are on a four-year cycle possibly because most of the fish mature at four years of age. Farther north, age five is also common. Pink salmon have a two-year life cycle. For coho it’s usually three years, while chinook or “spring” salmon return at any age from two to seven years. Chinook are the largest and most powerful of all salmon. In fact, the largest salmon ever caught in the world was a chinook weighing in at over 57 kilograms.

Ricker is famous for his mathematical model of fish population dynamics, now called the Ricker Curve, which he first described in a book he wrote in the 1950s on the computation of fish population statistics. Today that book is known throughout the world as the “Green Book.”

Ricker retired just before the age of personal computers, and he never used one. According to his son, Eric, his father was a man who had little interest in things that changed established, well-functioning habits. He never had a dishwasher, for example. Ricker used to tell a story about the time he uncovered some serious computer calculation errors with a few quick moves on his trusty old slide rule.

1. The Ricker Curve is still used all over the world to determine average maximum catches for regional fisheries. Each curve represents a different type of fish population. This is what governments use to decide how many days commercial fishers can be allowed to fish for salmon or cod, so that there are enough fish left to reproduce more than their current numbers the next year.

Line of natural replacement: Along this line, spawners (adult fish that lay eggs or fertilize them) are replaced by an equal number of progeny (fish that grow up to be adults).

2. Line of natural replacement: Along this line, spawners (adult fish that lay eggs or fertilize them) are replaced by an equal number of progeny (fish that grow up to be adults).

3. Salmon are interesting because their Ricker Curve looks more like this. At this point, at the top of the curve you have reduced the population to 40 percent of the natural equilibrium by fishing, but some fish, such as salmon, produce many more mature progeny when their spawning grounds are less crowded.

4. Natural equilibrium: At this point, spawners equal progeny. If there were no commercial fishery, this is where the fish population would tend to stay. In nature, fish don’t go much beyond this level because they get too crowded. Spawning beds get messed up and many eggs die.

5. For a fish species that followed Ricker Curve A, if commercial fishers were allowed to catch 20 percent of the mature spawners the fish population would be at this point. There would be fewer progeny, but enough to sustain the catch — a 20 percent surplus.

6. The point of maximum sustainable catch on any Ricker Curve is shown by the curving dotted line (“Sm” shows the maximum point for salmon). Note that it’s actually a bit to the left of the peak of a curve. This is because the distance between the curve and the natural replacement line is the greatest at this point. Anywhere to the left of this line, you are overfishing and will reduce the next generation’s harvest.

So You Want to Be a Fisheries Biologist

Ricker felt that anyone planning a career in science should be sure to choose a subject that is of great personal interest. Some aspects of scientific work can be boring, consisting of very repetitive experiments or endless data collection. Only a keen interest in the subject will make the tedium of the day-to-day work tolerable.

Explore Further

David R. Montgomery, King of Fish: The Thousand-Year Run of Salmon, Westview Press, 2003.

William Ricker, Computation and Interpretation of Biological Statistics of Fish Populations, Bulletin of the Fisheries Research Board of Canada no. 191, 1975. (This is “the Green Book.”)

Website of the Pacific Fishery Management Council.

Cyber Salmon website by Alaska Region of the U.S. Fish & Wildlife Service and the Fairbanks Fish & Wildlife Field Office.

Salmon lifecycle on the GoldSeal website.

Career Advice

So You Want to Be a Fisheries Biologist

Ricker felt that anyone planning a career in science should be sure to choose a subject that is of great personal interest. Some aspects of scientific work can be boring, consisting of very repetitive experiments or endless data collection. Only a keen interest in the subject will make the tedium of the day-to-day work tolerable.

Explore Further

David R. Montgomery, King of Fish: The Thousand-Year Run of Salmon, Westview Press, 2003.

William Ricker, Computation and Interpretation of Biological Statistics of Fish Populations, Bulletin of the Fisheries Research Board of Canada no. 191, 1975. (This is “the Green Book.”)

Website of the Pacific Fishery Management Council.

Cyber Salmon website by Alaska Region of the U.S. Fish & Wildlife Service and the Fairbanks Fish & Wildlife Field Office.

Salmon lifecycle on the GoldSeal website.

The Person

Birthdate
August 11, 1908
Birthplace
Waterdown, Ontario
Date of Death
September 8, 2001
Place of Death
Nanaimo, British Columbia
Family Members
  • Mother: Rebecca Rouse
  • Father: Harry Edwin Ricker
  • Spouse: Marion (Caldwell)
  • Children: 4 sons
  • Grandchildren: 3
Personality
Generous, modest, self-effacing, quiet
Favorite Music
Bach, e.g. Brandenburg Concertos, Handel, Mozart
Other Interests
Plants, birds, geology, insect classification, bass viol, Canadian history, languages, archaeology, trains.
Title
Retired Chief Scientist, Fisheries Board of Canada
Office
Nanaimo Biological Station, Canadian Department of Fisheries and Oceans
Status
Deceased
Degrees
  • BA, University of Toronto, Ontario, 1930
  • MA, University of Toronto, Ontario, 1931
  • PhD, University of Toronto, Ontario, 1936
Awards
  • Eminent Ecologist, Ecological Society of America, 1990
  • Order of Canada, 1986
  • Fry Medal, Canadian Society of Zoologists 1983
  • Flavelle Medal, Royal Society of Canada, 1970
  • Award of Excellence, American Fisheries Society, 1969
  • Gold Medal, Professional Institute of Public Service of Canada, 1966
  • Fellow of the Royal Society of Canada, 1956
Mentor
Professors Dymond, Walker, Coventry and Harkness, University of Toronto; W. A. Clemens and R. E. Foerster, Pacific Biological Station; F.I. Baranov’s for his 1918 Monograph about fish, R. A. Fisher for his book The Genetical Theory of Natural Selection.
Last Updated
August 21, 2006
Popularity
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Profile viewed 64555 times

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