CALGARY — Researchers are exploring whether the desire to have the plumpest, flakiest whitefish fillets on dinner plates may actually be gutting the evolution of the species in a northern Alberta lake and threatening a million-dollar industry.
Nets used by the commercial whitefish industry on Lesser Slave Lake have always been designed to catch the biggest and best fish.
But that means smaller fish are falling through the holes and now historical data indicates an inadvertent shift in how the species evolves, says Sean Rogers, a University of Calgary evolutionary biologist.
It’s the genes of the smaller whitefish that are being passed on, Rogers says.
“Instead of the bigger and best surviving, those were the ones we were actually removing from the population and consequently we elicited this selection response in the fish population.
“What you could see from the fishing with the gill nets was this average size for lake whitefish declining.”
Charles Darwin’s theory of natural selection has often been misrepresented over the years, explains Rogers.
It’s widely believed that the term “survival of the fittest” means only the bigger and stronger survive. But the theory actually refers to any survival traits that become more common in successive generations.
Whitefish are the backbone of Alberta’s freshwater fishing industry, which has an estimated worth of $1 million annually in the province and $18 million nationwide.
But the commercial fishery at Lesser Slave Lake has seen severe fluctuations in fish populations over time. Between 1965 and 1972 the fishery was actually shut down.
With the provincial fishing season preparing to open soon, Rogers’s molecular ecology lab has initiated a study to dig deeper into what’s happening. It will look at scale samples collected by the government over the last 30 years. The DNA from the samples should allow researchers to determine how the fishery has evolved over time.
“We’re launching this as a way of trying to get at the underlying mechanism of why this is happening and can we help reverse this or set it back on the right track?”
If the theory is proven, it won’t be the first time there has been evidence of man having an impact on genetics.
A 2003 study by David Coltman from the University of Alberta found that trophy hunters were driving down the horn size of bighorn sheep.
The report, published in the prestigious scientific journal Nature, said diminishing horn size was an evolutionary response caused by killing the largest rams before they reached their breeding peak.
“What you would normally expect for bighorn sheep is those that have the largest size and largest horns are those supposed to have the strongest reproductive quality, but unfortunately we remove them from the population before they have a chance to actually pass those genes on from one generation to the next,” said Rogers, who is familiar with Coltman’s study.
“As a result, it’s the other sheep that are reproducing.”