Living on the Edge: Management and Conservation of Atlantic Salmon at the Southern Limit of the Species Distribution

Abstract

Atlantic salmon (Salmo salar L.) are an emblematic anadromous fish species that inhabit marine and freshwater ecosystems in the Northern Hemisphere. In Portugal, the southern limit of its global distribution range, the species is classified as Critically Endangered (CR), and occurs only in the Minho and Lima rivers, which hold the most abundant populations, with occasional confirmed occurrences in the Cávado and Douro rivers. In this region, the species faces several highly detrimental threats (e.g., dams and other obstacles, unsuitable fishing legislation, and climate change), but some knowledge gaps about the biology, ecology, and structure of these southern populations often impair any attempt to define and implement effective management and conservation programs. We present the objectives, actions, and preliminary results of a set of projects and partnerships, recently implemented in Portugal, focused on increasing knowledge about local salmon populations to contribute to the development of suitable management guidelines for the target species. Within the project “SALMONLINK—Contribution of scientists and fishermen to the conservation and participatory management of Atlantic salmon populations in Portugal”, several actions have been implemented for the past three years to improve knowledge about this species, including the assessment of salmon distribution and abundance, adult and juvenile migration patterns, and population structure. In complement to these measures, we are also implementing (in Portugal) the international projects “SMOLTrack III & IV—Quantifying smolt survival from source to sea: informing management strategies to optimize returns”, which are specifically focused on smolt seaward migration and aim to obtain more information on this particularly vulnerable life-stage. Combined with a strong link with the local commercial and recreational fishing communities, who are providing data on salmon catches and contributing to an overview of the socioeconomic value of salmon in Portugal, these projects will contribute to increasing the knowledge of these populations, and at the same time, within the context of the constant transfer of knowledge between all the involved parties, advise the adaptation of the current fishing legislation to the conservation and management requirements of this highly endangered species