Chondrostoma  (Chondrostoma beysehirense)

Chondrostoma beysehirense is classified as Endangered (EN) on the IUCN Red List (1).

A rare fish, Chondrostoma beysehirense has an elongated body which is flattened from side to side (2) (3). The genus name Chondrostoma is derived from the Greek words ‘chondros’ meaning cartilage, and ‘stoma’ meaning mouth (4), and refers to the characteristically horny layer of the prominent lower lip (2) (3) (4). The narrow, elongated snout has a rounded tip (3).

The upperparts of Chondrostoma beysehirense are light brown, and this colouration gradually turns creamy-white towards the underside (3).

Chondrostoma beysehirense is endemic to Turkey (1) (2) (3), where it is restricted to just one stream flowing into Lake Beyşehir. This species does not actually enter the lake itself, as a waterfall blocks the entry route (1).

The stream in which Chondrostoma beysehirense lives is very small, and this species is thought to occupy an area of less than ten square kilometres (1).

Shallow areas of river with coarse substrates including gravel, stones and pebbles are the preferred habitats of Chondrostoma beysehirense (3).

The biology of Chondrostoma beysehirense is poorly understood, although it is known to be a detritus feeder. It is also migratory to a small extent, as it feeds and reproduces in different areas of its stream habitat, migrating to springs upstream to spawn (1).

Chondrostoma beysehirense is a member of the order Cypriniformes. In general, cyprinoids are largely freshwater, egg-laying species, all of which lack jaw teeth. The Cypriniformes are composed of five different families, the largest of which is the Cyprinidae, to which Chondrostoma beysehirense belongs. This family consists of more than 2,000 species, including chubs, minnows and carps. As with most cyprinids, it is assumed that Chondrostoma beysehirense does not exhibit sexual dimorphism (5).

Although the extent of threats to Chondrostoma beysehirense is not well known, the species may be at risk from activities such as water extraction, aquaculture and the construction of dams and weirs. Habitat loss, eutrophication and pollution all pose additional threats, while the introduction of non-native and invasive species may also impact the population of Chondrostoma beysehirense (3).

Although no data on population size exist, in 1998 there were thought to be fewer than 250 mature Chondrostoma beysehirense remaining in the stream (1).

The area around Lake Beyşehir is designated as a national park, meaning that the parts of the stream in which Chondrostoma beysehirense occurs should receive some level of protection (1) (3).

Further survey work has been suggested in order to assess and confirm the current population size of Chondrostoma beysehirense (1) (3). Recommended conservation actions for this species include protecting the remaining populations of Chondrostoma beysehirense outside of the national park, and collecting detailed information on its biology and ecology. Improving water management in this species’ habitat, and regulating the water regime of Lake Beyşehir, particularly during the dry seasons, would also be beneficial to Chondrostoma beysehirense (3).

Introducing Chondrostoma beysehirense to other tributaries and to the main lake is not an option, as these areas contain introduced species, which could be predatory or compete with this species for food and space (1).

More information on freshwater fish:

• IUCN/SSC Freshwater Fish Specialist Group:
  http://www.wetlands.org/Default.aspx?TabId=201&language=en-US