Desert rivers are highly dynamic systems in which dry periods, frequently involving the cessation of superficial flow, alternate with violent flash floods. In spite of their territorial importance and high functional and biological diversity, desert rivers have received little attention in the scientific literature, especially in Northern Africa. This study investigated the distribution of non‐native fish, their relationship with river damming and their potential impacts on native biodiversity in the main river basins draining arid areas of Morocco (Oued Draa, Oued Ziz and Oued Ghir), based on field sampling covering 84 stream reaches. Thirteen fish species were recorded, eight of which are non‐native. Two species (stone moroko, Pseudorasbora parva, and bleak, Alburnus alburnus) had not been previously recorded in Morocco, while the native sandsmelt (Atherina boyeri) had not been cited as an invader. Pumpkinseed (Lepomis gibbosus) was the most widely distributed non‐native fish. Non‐native fish species were associated with reservoirs, colonizing the regulated downstream reaches. In contrast, unregulated upstream reaches tended to be free of non‐natives. The low abundance of native fish in reservoirs seems to be caused by the impacts of introduced fish species. Management options for environmental flow are limited, owing to reduced water availability. Non‐native fish management should thus focus on limiting the spread of species already introduced and avoiding new introductions, especially into reservoirs. Copyright © 2014 John Wiley & Sons, Ltd.

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Montane biota is vulnerable to climate change, especially in the case of relict species in environmentally extreme areas. The Dades trout Salmo multipunctata is a relict species from the Draa basin, on the southern slopes of the High Atlas Mountains, Morocco. Apart from its genetic and morphological singularity almost nothing is known about this species. We surveyed the whole potential distribution range of the Dades trout and found that only two isolated populations exist (in the Dades and M'Goun catchments), occupying an extremely small range, < 22 km of stream reaches in a narrow altitudinal range (c. 2,150–2,375 m). The species was found more frequently and more abundantly at intermediate elevations within its range, and somatic condition increased with altitude. Climatically suitable areas for the Dades trout will be confined to mountain summits without permanent water bodies by 2070. The Dades trout is a Critically Endangered species in need of active management for its persistence. We propose actions for the long-term conservation of the species, including catchment-scale erosion control, riverbed restoration, local-scale measures to mitigate global warming, and an ex situ breeding programme.

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