Abstract The global decline in wild populations and the growing demand for bioresources have spurred efforts to enhance wildlife populations through captive breeding programmes. However, the success of these initiatives remains limited. Using data from a long-term captive breeding programme conducted by a national salmon hatchery in Japan, I examined the influence of an individual’s origin on mortality in captivity. My results showed that wild individuals had higher mortality rates in captivity than captive-bred individuals. These findings suggest that efforts to enhance wildlife populations through captive breeding can result in the loss of wild individuals with high fitness in the wild and the ability to enhance their offspring’s fitness in the wild, underscoring the need for approaches that lower the mortality of wild individuals in captivity.
Genki Sahashi (Wed,) studied this question.