Environment: milieu / climate zone / depth range / distribution range
Freshwater; benthopelagic; potamodromous (Ref. 59043). Temperate; 6°C - 18°C (Ref. 2059); 50°N - 44°N, 8°E - 21°E
Europe: Danube drainage. Introduced into other European river basins when their numbers declined due to ecological changes in the Danube. Appendix III of the Bern Convention (protected fauna).
Length at first maturity / Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 150 cm TL male/unsexed; (Ref. 11243); common length : 70.0 cm TL male/unsexed; (Ref. 682); max. published weight: 52.0 kg (Ref. 719); max. reported age: 20 years (Ref. 59043)
Morphology | Morphometrics
(total): 3 - 5;
soft rays: 7 - 14;
Vertebrae: 66 - 72. Distinguished from other species of Salmonidae in central and eastern Europe by the following combination of characters: lateral line with 180-200 scales; no red spots and white fin margins; head dorsally flattened and long ( 22-24% SL); body roundish; caudal fin deeply emarginate; large size (in undisturbed areas); usually 13-19 gill rakers (Ref. 59043).
Usually solitary, inhabits deeper regions of swift flowing streams with oxygen rich waters. Adults are territorial but not solitary (Ref. 26170). Carnivore. Juveniles feed mainly on invertebrates and adults mostly on fishes, but also prey on amphibians, reptiles, small mammals and waterfowl (Ref. 26170). Important sport fish with minimum size of catch from 50-55 cm. Transplantations of young artificially incubated and reared fish have not been successful. Depletion of stocks due to overexploitation, industrial pollution, waterway redirection and badly designed or non-existent fish ladders in dams and reservoirs. Territorial, but migrates short distances upstream for spawning (Ref. 556). Reported to be one of the biggest freshwater fishes of the world, reaching a length of over 2 m and weight of over 100 kg (Ref. 26170); which is probably erroneous (A. Mangold, pers. comm.).
Sexually mature fish migrate upstream into smaller and shallower (0.3-1.5 m deep) streams (Ref. 26170), usually in upper reaches of tributaries (Ref. 59043). Males arrive first at spawning sites. Males defend females against other individuals. Spawning usually occurs during daytime (Ref. 59043). Spawns on gravelly bottom where female makes a shallow hole where the eggs are laid and covered with gravel (Ref. 682). Both sexes covered the eggs with substrate. They both defend the spawning site up to 2 weeks after spawning. Eggs usually hatch after 25-40 days. Larvae stay in gravel until yolk sac is absorbed after 8-14 days (Ref. 59043). Young remain near spawning area feeding on bottom fauna. Spawns with snow melt, in shallow water in Danube or affluents (Ref. 682).
Kottelat, M., 1997. European freshwater fishes. An heuristic checklist of the freshwater fishes of Europe (exclusive of former USSR), with an introduction for non-systematists and comments on nomenclature and conservation. Biologia, Bratislava, 52/Suppl. 5:1-271. (Ref. 13696)
IUCN Red List Status (Ref. 125652)
Threat to humans
Fisheries: commercial; aquaculture: commercial; gamefish: yes
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingNutrientsMass conversion
Estimates based on models
Phylogenetic diversity index (Ref. 82804
= 0.5625 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.01230 (0.00726 - 0.02086), b=3.01 (2.86 - 3.16), in cm total length, based on LWR estimates for this species & (Sub)family-body (Ref. 93245
Trophic level (Ref. 69278
): 4.2 ±0.74 se; based on food items.
Generation time: 11.0 ( na - na) years. Estimated as median ln(3)/K based on 2 growth studies.
Resilience (Ref. 120179
): Low, minimum population doubling time 4.5 - 14 years (tm=5; tmax=20).
Fishing Vulnerability (Ref. 59153
): High to very high vulnerability (68 of 100).