How can we fix this problem? You might think that simply halting the harvest based on size would cause the fish populations to return to “normal.” However, looking at the problem from an evolutionary perspective paints a different picture. When the fish evolved smaller body sizes in the first place, the genetic makeup of the population changed — genes for small size became much more common. And those genes won’t disappear when the selection does. They will remain until they are removed from the population through evolution, and that could take a long time! As David puts it, “When you stop fishing, nature doesn’t automatically exert selection pressure back in the other direction very quickly.”

Even worse, there may be no “normal” to return to. At the same time that we’ve been fishing our wild populations down in size, we’ve been changing their habitats. David suggests that it’s hard to tell how fish populations might evolve once selective harvesting stops “because the environment itself is so different…than the one that originally caused their life history to evolve as it did….We’ve changed the oceans considerably through harvest, through habitat destruction, through climate change — and evolution is a very dynamic process. It’s not something that takes thousands of years to change. But in the strategies we’ve designed to engage in conservation of natural resources, in the past we have not considered evolution to be a dynamic force; we’ve considered the characteristics of organisms to be fixed — and they’re not.”