Sunbleak
Belica
Leucaspius delineatus (Heckel, 1843)
Order Cypriniformes
Family Cyprinidae
Conservation status: in Bulgaria: Vulnerable VU [B1a, b (ii, iii, iv)]; International: IUCN [LR/lc], BeC-III.
General distribution. The fresh water basins of Central and Eastern Europe from France eastward to the Volga River basin. In the north, it reaches Southern Sweden. It is introduced to Great Britain.
Distribution and abundance in Bulgaria. In the past, the species was found only in the Dyavolska River [1]. For a long time, it was not recorded anywhere and it was considered absent in Bulgaria [2]. Later, it was found in Beloslav Lake [3], in marshes and canals of the Provadiyska River [4] and in the mouth of the Devnya River [5]. It was also found in the Kamchiya River basin, near the mouth, and in the region of the Krusha fish ponds [6], as well as in the Danube River [7]. Gradually, the species disappeared in most of its previous habitats. In Beloslav Lake it was reported as very rare as early as the 1960s [8], and at present it is no longer found there. The occurrence of the species in the Black Sea rivers needs confirmation. In 2005-2006, it was found only in the Danube (near the villages of Novo Selo, Gomotartsi, Koshava, Simeonovo, Archar and Stanevo) and the adjacent wetlands, such as the Orsoya fish ponds [our data].
Habitats. The lower reaches of permanent rivers and coastal fresh water lakes. It inhabits calm waters overgrown with vascular aquatic plants.
Biology. A shoaling fish. It reaches sexual maturity in the second year. Spawning takes place in shallow waters, among abundant aquatic vegetation, in the period from April to June. The females lay the eggs in strings wound spirally around plant stems with the help of elongated urogenital papillae. The fecundity of females ranges from 80 to 2 300 eggs. It feeds on phytoplankton and zooplankton, reaching a maximum body length of 9-12 cm. It has a life span of about 5 years [9, 10].
Similar species. It greatly resembles the young bleak (Alburnus alburnus), from which it can be differentiated by the absent or incomplete lateral line with 1-12 scales anteriorly.
Negative factors. Changes in the hydrological regime and pollution of the coastal lakes and the Black Sea rivers, as well as the pollution of the Danube River which resulted in a loss of the species habitats. A negative factor is also the competition of non-indigenous fish species.
Conservation measures taken. The species was listed in the Red Data Book of Bulgaria (1985).
Conservation measures needed. Development and implementation of an Action Plan for the protection of the species in Bulgaria. Restoration and protection of the coastal wetlands and lower reaches of rivers against pollution.
References. 1. Kovatcheff, 1923; 2. Drensky, 1948; 3. Stojanov, 1949; 4. Pechev, 1970; 5. Sivkov, 1974; 6. Manolov, Sivkov, 1977; 7. Vassilev, 1994; 8. Gheorghiev, 1967; 9. Holcik, 1998; 10. Maitland, 2000.
Authors: Tihomir Stefanov, Teodora Trichkova
