The commercial white fish industry on Lesser Slave Lake in Alberta, Canada is a multi-million dollar business that hinges upon catching the biggest fish. To optimize the industry fisherman have developed nets that have holes big enough for the smaller fish to pass through, while capturing the larger white fish, which will yield a larger profit. This selective fishing, however, is having an effect on the whitefish population in Alberta on an evolutionary time scale. Since people are selectively removing the larger fish, only the smaller fish are able to pass on their genes to the next generation and thus the whitefish are now smaller on average.
This is the hypothesis of Sean Rogers, a University of Calgary evolutionary biologist for why fishermen are observing that the average whitefish size is declining and their gill nets are pulling in fewer and fewer fish. He plans to test this theory using DNA samples that have been collected by the government over the past 30 years to determine if this is merely a coincidence or their has actually been a change in the DNA of the whitefish so that they develop into smaller fish.
When discussing his hypothesis Rogers brings up the crucial point in evolution that is often misunderstood, the question of, “Survival of the Fittest.” Ever since the evolution became widely accepted in the scientific community with the publishing of Charles Darwin’s On the Origin of Species, the general public has associated it with the idea that the biggest and strongest species will survive. This, however, is not the case. Evolution, in short, states that the specie that is best suited for the environment will propagate and pass on its genes to the next generation. This does not, however, mean that the biggest will always be the best. In the case of the whitefish, the fish that was most likely to survive changed throughout the course of history, because the introduction of the commercial fishing industry changed their environment. Before people were introduced to the equation, it was most advantageous for the fish to grow big and strong, because then they could win the battles for food. When people started fishing for great numbers of whitefish, however, it became more advantageous for them to be smaller, because the advantage of being big in order to win battles with each other over resources was strongly overpowered by the disadvantage of the increased probability of getting caught in the net of a fisherman. In short, bigger is not always better.