Iberian arched-mouth nase  (Iberochondrostoma lemmingii)

The Iberian arched-mouth nase is classified as Vulnerable (VU) on the IUCN Red List (1).

The Iberian arched-mouth nase (Iberochondrostoma lemmingii) is a small fish belonging to the Cyprinidae family, a diverse group of fish comprising over 2,000 species (4) (5). As its name suggests, this species is distinguished by its arched mouth, which is lacking in barbels (4) (6).

Generally, the body of the Iberian arched-mouth nase is covered in small, yellowish-green scales, while its entire body may also be covered in small, black spots (4) (6). The anal fin is slightly smaller than the dorsal fin, with the edge of both fins curving outwards. The tail of the Iberian arched-mouth nase is slightly forked (6).

The female Iberian arched-mouth nase is slightly larger than the male (3).

The Iberian arched-mouth nase is native to Portugal and Spain, where it only occurs in the Tajo, Guadiana, Odiel and Guadalquivir river basins (1) (4).

The Iberian arched-mouth nase inhabits the middle reaches of streams with a moderate current, and also the lower reaches of rivers with a slow current. This species prefers the presence of abundant aquatic vegetation (1) (2).

The Iberian arched-mouth nase is a benthopelagic species, meaning it lives and feeds mainly near the bottom of the water column (2). It is omnivorous, feeding on a range of food types including algae, plants, zooplankton, and invertebrates (2) (3). Members of the Cyprinidae family lack teeth in the jaws, instead processing food using modified bones in the throat, known as ‘pharyngeal teeth’ (5).

The breeding season of the Iberian arched-mouth nase begins in March or April, and lasts until May (2) (3) (7). This species reaches sexual maturity in the second year of life, and the female can spawn twice per year (7). It is a fast growing and relatively short-lived species, with the maximum lifespan of the Iberian arched-mouth nase being around four years (7).

A rare species, the Iberian arched-mouth nase is believed to have suffered more than a 30 percent reduction in its population size over the last 10 years (1). The main cause of this decline is believed to be the loss of its habitat through water extraction for crop irrigation and the building of dams (1) (4) (6). The extraction of material from rivers has also lead to increased turbidity, which can cause suffocation of fish due to the build up of particles in the gills. It has also caused the destruction of this species’ spawning grounds (6) (8).

Further threats to the Iberian arched-mouth nase include pollution and the introduction of exotic predators such as non-native fish and crayfish (1) (6). It is also feared that introduced species may bring disease to which the Iberian arched-mouth nase has no immunity (8).

The Iberian arched-mouth nase is currently protected by its listing on Annex II of the European Union Habitats Directive and Appendix III of the Bern Convention (1) (9) (10). Major conservation aims for this species include increasing the existing population and restoring this species’ habitat (8). In order to achieve these aims, a greater area of this species range needs to be protected (6). Control of invasive species is also hoped to have a positive impact on the Iberian arched-mouth nase population (8).

Future construction of dams and reservoirs should take into account the requirements of this species during planning (8), and water conditions where Iberian arched-mouth nase juveniles are present must be carefully monitored, especially when the river flow is low (6). In order to restock rivers in the future when this species’ habitat has been restored, a captive breeding population needs to be established (6).

As well as a public awareness campaign, more research is needed into the ecology of the Iberian arched-mouth nase in order to better understand how to conserve it (8).

Find out more on the Iberian arched-mouth nase:

• FishBase - Iberochondrostoma lemmingii:
  http://www.fishbase.org/Summary/speciesSummary.php?ID=9940&genusname=Iberochondrostoma&speciesname=lemmingii