Bullhead
Cottus gobio Linnaeus, 1758
Cottus gobio haemusi Marinov & Dikov, 1986: Marinov, Dikov, 1986: 18.
Order Scorpaeniformes
Family Cottidae
Conservation status: in Bulgaria: Critically endangered CR [A1a+2; B1a, b; E], BDA-II; International: IUCN [LR/lc], HD-II.
General distribution. The rivers in all of Europe, excluding Italy, Greece, Eire and the northern parts of Norway, Sweden and Finland.
Distribution and abundance in Bulgaria. In Bulgaria, it is found in the upper reaches of some Danube tributaries – Ogosta, Iskar, Vit, Osam and Yantra Rivers [1, 2, 3, 4, 5, 6, 7, 8]. In recent years, the species has become very rare, having decreased in abundance and disappeared in many of its former habitats. At present, it is found in the following rivers: Dalgodelska Ogosta upstream the village of Dalgi Del, Berkovska upstream Berkovitsa, Malki Iskar upstream Etropole, Beli Vit near Ribaritsa, Toplya (a tributary of the Vit) and Beli Osam upstream Troyan [our data].
Habitats. The upper reaches of rivers with sandy and gravel bottom and cold, fast-flowing water.
Biology. A benthic species. It reaches sexual maturity in the second year. The spawning period is from April to May. The fecundity of females is very low: between 100 and 300 eggs. After fertilization, the eggs are laid attached to undersides of large stones and are guarded by the males. It feeds on different invertebrate animals and small fish [6, 9].
Similar species. In Bulgaria, none.
Negative factors. Loss (degradation) of habitats as a result of river regulation by barrages and weirs; water pollution; clear-cutting in the mountain regions resulting in river siltation and flooding; competition with introduced fish species (for example, the rainbow trout, Oncorhynchus mykiss).
Conservation measures taken. The species was listed in Annex II of the Biological Diversity Act (2002).
Conservation measures needed. Development of an Action Plan for the protection of the species in Bulgaria. Inclusion of the river sections where the species occurs in the Natura 2000 network of protected areas.
References. 1. Kovatcheff, 1923; 2. Chichkoff, 1939; 3. Drensky, 1951; 4. Marinov, Dikov, 1986; 5. Karapetkova, 1994; 6. Karapetkova, Zivkov, 1995; 7. Dikov et al., 1994; 8. Trichkova et al., 2004; 9. Maitland, 2000.
Authors: Tihomir Stefanov, Teodora Trichkova
