Management of a highly unlikely native fish: The case of arctic charr Salvelinus alpinus from the Southern Alps

As a result of ancient introductions, some alien species are erroneously considered native. Salvelinus alpinus (Linnaeus, 1758) is hypothesized to have survived as a postglacial relic in the northern European Alps, although documented ancient introductions contradict its native status in a few mountain lakes from the southern Alps (Trentino Alto Adige, Italy). Regardless of its uncertain origin, its recent expansion across the southern Alps (introduced into >170, mainly originally fishless, high-altitude lakes) was the result of management and alleged conservation actions. The present study is a review of the origin of S. alpinus in the southern Alps, and of the appropriateness of management and conservation actions. The autochthony of S. alpinus in this region is rejected by multiple lines of evidence and its presence is most likely the result of historical introductions. Only the origin of two populations occurring at lower altitude is uncertain, as they may be native. Residual uncertainty makes it difficult to evaluate the conservation status and value of the Italian populations of S. alpinus, but it does not prevent the highlighting of several errors in the past and the present management of this species. Past and present introductions have altered the original genetics of the ancient populations and have contributed to the invasion of montane aquatic habitats by modern domestic fish. Although it is now timely to consider the adverse ecological consequences of fish stocking, the many introductions of S. alpinus are associated with a misleading conservation rhetoric, providing ambiguous educational messages to people and relevant stakeholders, and probably diverting resources intended for biodiversity conservation. A non-intervention approach (i.e. not to stock or fish S. alpinus) would have been the wiser strategy to preserve ancient populations, their supposed conservation value, and their actual cultural value. Even now, this strategy is probably the best option, while planning definitive research.