We have been stocking salmon for a long time. From the middle of the nineteenth century salmon managers have been collecting adults from rivers, breeding them in hatcheries, rearing their offspring to some age, then releasing those offspring back into rivers to interact with wild-born fish. When we started stocking Darwin and Wallace were still developing their ideas about how natural selection drives adaptive evolution. Mendel was breeding peas to uncover the simplest principles of inheritance. By breeding and rearing salmon in hatcheries, we were driving maladaptation by artificial selection before we even understood adaptation by natural selection.
During the first half of the twentieth century paleontologists, evolutionists, ecologists, and geneticists drew upon the ideas of the early naturalists to study everything from fruit flies to dinosaurs. By the middle of the twentieth century this collective effort culminated in a period known as the Evolutionary Modern Synthesis. The goal of naturalists changed from naming and counting organisms to understanding how animals came to be, and not to be.
Salmon managers were not paying attention. They were busy refining and industrializing hatchery technology, resulting in the first collateral catastrophe of stocking: the damming of many of the world’s great salmon rivers. Had we not been able to build huge hatcheries to replace fish lost by building dams, surely fewer would have been built— public outrage and commercial fishers wouldn’t have allowed it. But when hatcheries offered society the promise of electricity, water for irrigation and drinking, and salmon, destroying river ecosystems was easy.