Nowhere to swim to: climate change and conservation of the relict Dades trout Salmo multipunctata in the High Atlas Mountains, Morocco

Abstract

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.

Moroccan desert rivers: fish on the arid extreme of Mediterranean streams

“…We could not confirm previous information on the presence of redbelly tilapia or African jewelfish (Hemichromis bimaculatus) in the Ghir basin, which had been reported from the Algerian part of the basin in the early 20 th century (Qninba and Mataame, 2009 The Dades trout (Figure 11) is a critically endangered species with a tiny distribution range, probably among the smallest of any stream salmonid worldwide (Clavero et al, 2017). It occupies less than 22 km of stream reaches in a narrow elevation band (roughly 2150 to 2375 masl), being thus extremely vulnerable to warming climatic conditions and to any possible catastrophic event.…”

“…In our specific study area, conservation efforts are urgent for the Dades trout (Clavero et al, 2017) and the Sahara aphanius (Bacha and Freyhof, 2017). It is also relevant to avoid the introduction of new non-native species, as well as avoiding the expansion of those already established through their introduction to basins where they are not present yet.…”

“…It occupies less than 22 km of stream reaches in a narrow elevation band (roughly 2150 to 2375 masl), being thus extremely vulnerable to warming climatic conditions and to any possible catastrophic event. Clavero et al (2017) propose specific measure to enhance its conservation chances, including habitat restoration and improvement (involving stream channels, riparian vegetation and the drainage areas), the establishment of new population nuclei and the start of a captive breeding program. Of critical importance to maintain the integrity of the Dades trout uniqueness is avoiding any trout stocking in the Draa basin, involving either trout from other Moroccan lineages or American trout.…”

Salmo macrostigma(Teleostei, Salmonidae): Nothing more than a brown trout (S. trutta) lineage?

“…In the brown trout Salmo trutta L. 1758, natural diversity is notably characterized by complex patterns of phenotypically distinct geographic forms and considerable life‐history variation (Bernatchez et al ., ; Elliott, ; Kottelat & Freyhof, ; Sanz, ). In addition to S. trutta and Salmo salar L. 1758, studies of biological variation during the last century have led to the description of several Salmo L. 1758 species, often having very restricted geographical ranges (Berrebi et al ., ; Clavero et al ., ; Ninua et al ., ). Depending on the source, the number of Salmo species ranges from around 25 (IUCN, ; Kottelat & Freyhof, ) to nearly 50 (FishBase; http://fishbase.mnhn.fr).…”

Stop draining the swamp: it's time to tackle wetland loss

“…This issue of Oryx delves into the problems confronting a wide range of wetland-dependent species. Small, fragmented, isolated wetlands are the last refuge for some: for the range-restricted Dades trout in Morocco climate change is likely to reduce suitable habitat (Clavero et al, 2018), and in Asia once-common otters (Li & Chan, 2018) and fishing cats (Thaung et al, 2018) persist only in remnant populations that often lie outside protected areas.…”