Burbot
Lota lota (Linnaeus, 1758)
Lota vulgaris Cuv.: Kovatcheff, 1923: 49.
Order Gadiformes
Family Gadidae
Conservation status: in Bulgaria: Vulnerable VU [A1b, d; B1b, c].
General distribution. The northern parts of Europe, Asia and North America.
Distribution and abundance in Bulgaria. In the past, it was very abundant in the Danube River, and it was found in its tributaries: the Iskar River (as far upstream as Mezdra and Roman, rarely even reaching Vrazhdebna), and the Yantra River (near the village of Dolna Studena, and its tributary the Rositsa River) [1, 2, 3, 4, 5]. Later, the species was recorded in the Danube River, the Iskar River (rare, reaching upstream Cherven Bryag) and the mouth of the Yantra River [6, 7, 8, 9, 10]. At present, it is found only in the Danube [our data]. In the period from 2002 to 2005, its annual catch decreased 7-fold [11].
Habitats. It is found in permanent large rivers with slow current and in deep lakes.
Biology. Cold water and nocturnal species. In the summer, it is slightly active, and during the day it hides in deep holes, under rocks, among roots of trees and dense aquatic vegetation. During the night, it moves to shallow areas to feed. Depending on the geographical region that it inhabits, the species reaches sexual maturity between the first and eighth year. Spawning occurs in winter (December-March) at water temperature of about 0°C. The fecundity of females ranges from 100 000 to 3 000 000 eggs. The juveniles feed on crustaceans, insect larvae and mollusks, while the adults feed mainly on fish. It attains a maximum length of 150 cm and a maximum weight of 34 kg. The maximum age reached is 20 years, but usually the life span is 10-12 years [12, 13].
Similar species. None.
Negative factors. The main threat to the species is water pollution.
Conservation measures taken. The species was listed in the Red Data Book of Bulgaria (1985).
Conservation measures needed. Protection of the Danube River against pollution.
References. 1. Kovatcheff, 1923; 2. Drensky, 1930; 3. Morov, 1931; 4. Chichkoff, 1939; 5. Drensky, 1951; 6. Paspalev, Peshev, 1955; 7. Karapetkova, 1972; 8. Marinov, 1978; 9. Karapetkova, 1994; 10. Karapetkova, Zivkov, 1995; 11. Ministry of Agriculture and Forestry, 2002-2005; 12. Froese, Pauly, 2006; 13. Jacobs, Wehrly, 2006.
Authors: Teodora Trichkova, Tihomir Stefanov
