Threatened fishes of the world: Squalius torgalensis (Coelho, Bogutskaya, Rodrigues & Collares-Pereira, 1998) (Cyprinidae)

Abstract

Common name: Escalo do Arade (Portuguese). Conservation status: Critically Endangered according to the Portuguese Red Data Book (Cabral et al. 2005). Identification: Small cyprinid with 131mm of maximum standard length and 35–42 canaliculate scales on the lateral line, 7–8.5 scales above the lateral line, 2.5–3 scales below the lateral line, 8 dorsal and 7–8 anal fin rays. Pharyngeal teeth are two-rowed (2.5–5.2); vertebral formulae are 21+17 or 21+16; preopercular–mandibular cephalic sensory canal communicates with infraorbital canal; and fourth and fifth infraorbitals are large and completely fused (Coelho et al. 1998). Illustration: Marcos Oliveira. Distribution: This species is endemic to Portugal and occurs in the rivers Arade, Seixe, Algibre, Bordeira, Aljezur, Alvor and Quarteira. It was isolated from its sister species, Squalius torgalensis, around 5.13 MYago due the uplift of the Caldeirao Mountains (Sousa-Santos et al. 2007). Abundance: It is estimated that the number of mature individuals is higher than 10.000 but strong seasonal fluctuations may occur (Cabral et al. 2005). Habitat and ecology: Generalist species, inhabiting a broad range of habitats outside the reproductive season—in spring migrations towards higher velocity areas with coarse substrata seem to occur (Santos and Ferreira 2008). Reproduction: Breeding season is expected to be similar to that of S. torgalensis: March to June. Extensive hybridization with Squalius alburnoides occurs in the Quarteira River (Sousa-Santos et al. 2006). Threats: Dams, proliferation of introduced exotic species, water scarcity, habitat degradation and loss of water quality. Conservation: Some efforts are being conducted to the ex situ reproduction of this species. Conservation recommendations: Habitat restoration of some stretches followed by restocking with fish produced in ex-situ breeding programmes. Mesquita et al. (2005) suggested that conservation efforts should pay particular attention to isolated populations and smaller drainages, where low levels of genetic diversity were found (as a Environ Biol Fish DOI 10.1007/s10641-009-9550-z