September 17, 2023 — In a recently published global synthesis consisting of 206 peer-reviewed studies from 1970 through 2021, conclusions emphasize the detrimental effects that hatchery salmon have on wild populations. The research, published by Fisheries Management and Ecology in July 2023, highlights how human efforts to bolster wild salmon numbers through hatchery programs have hindered rather than helped their populations.
The authors of the global synthesis study acknowledged the complexity of the issue, stating that their aim was to provide a transparent and updatable synthesis of existing research without delving into the social, political, and legal aspects surrounding hatcheries. The study focused solely on evaluating the scientific evidence related to the impacts that hatcheries have on wild populations.
Before delving into the study’s findings, it’s important to understand the distinction between wild and hatchery salmon. Wild salmon are those that live and breed in their natural environments without human interference, evolving over generations to adapt to their surroundings through natural selective pressures. On the other hand, hatchery salmon are artificially bred and raised in controlled environments, with certain selective pressures removed, such as female choice and male-to-male competition. Omitting these pressures allows for unnatural juveniles to survive, later introducing hatchery salmonids to wild populations through largescale releases into the North Pacific.
Researchers found that large releases of hatchery salmonids triggered adverse density-dependent responses in various co-mingling populations of wild salmonids. These responses encompassed reduced survival, growth, fecundity, body size, and abundance of wild salmonids that rely on the same common pool prey resource. The effects were observed across different species and countries, suggesting the wide-ranging nature of the issue.