Black Sea Roach
Kutum
Rutilus frisii (Nordman, 1840)
Rutilus frisii velecensis Chichkoff, 1932: Chichkoff, 1932: 355; Drensky, 1948: 23.
Order Cypriniformes
Family Cyprinidae
Conservation status: in Bulgaria: Critically endangered CR [A1a; E]; International: IUCN [DD], BeC-III.
General distribution. In the lower reaches of the rivers flowing into the Black Sea and the western part of the Caspian Sea.
Distribution and abundance in Bulgaria. It has occurred in the rivers Karaagach, Veleka and Rezovska [1, 2, 3, 4, 5, 6, 7]. A very rare species of low abundance. The population in the Karaagach River can be considered extinct, as during studies in 2005, the species was not recorded [8]. In the Veleka River, it was found only in the lowest reaches, downstream the village of Brodilovo, where the population was of low abundance and biomass [6, 7]. There are no data about the state of the population in the Rezovska River.
Habitats. It is found in permanent rivers, including their estuaries.
Biology. It lives in small shoals mainly in the deep parts of the rivers. It reaches sexual maturity at the age of 2-4 years. Spawning occurs in April-May. The species migrates upstream and lays its eggs in shallow water, among weeds and over stony substrate. The fecundity of females ranges between 90 000 and 250 000 eggs. The species feeds on algae and small invertebrate animals. It reaches a maximum length of 60 cm and a maximum weight of 1,5 kg [5].
Similar species. The roach (R. rutilus) and the European chub (Leuciscus cephalus). The Black Sea roach is easily distinguished from the roach by the higher number of scales in the lateral line (58-61). By the same feature it also differs from the European chub, which it greatly resembles with the colour of the body. The scales in the lateral line of roach are 40-44, those in the European chub are 43-47.
Negative factors. Water pollution, rapid growth of tourism and recreation development along the Black Sea coast, which is causing the loss of the last habitats of the species in Bulgaria; pressure from introduced fish species; poaching.
Conservation measures taken. One of the habitats of the species is included in the Mouth of the Veleka River Protected Area.
Conservation measures needed. Introduction of a total ban on the fishing of the species. Inclusion of the lower reaches of the rivers Veleka and Rezovska in the Natura 2000 network of protected areas.
References. 1. Chichkoff, 1932; 2. Drensky, 1948; 3. Drensky, 1951; 4. Karapetkova, 1976; 5. Karapetkova, Zivkov, 1995; 6. Karapetkova, 2003; 7. Dikov, Zivkov, 2004; 8. Trichkova et al., 2006.
Authors: Tihomir Stefanov, Teodora Trichkova
