The diet of the otter (Lutra lutra L.) was assessed through spraint analysis at three different streams in the Beskydy Mountains (north-east Czech Republic) and compared with fish availability and river management procedures. The remains of 3 478 prey items were recorded in 894 spraints, collected between May 2000 and May 2002. Fish were the dominant species taken (90%), followed by amphibians (50%). The most frequently occurring species of fish were the Carpathian sculpin Cottus poecilopus (71%) and brown trout Salmo trutta m. fario (65%). The composition of the otter’s diet tended to reflect the fish availability (biomass) in streams. Despite the general similarity of the different streams studied, diet composition differed significantly. The differences in diet could be explained by differences in fishery management (stocking) together with the location of migration barriers.
The spawning migration from Moravka reservoir to the Moravka river tributary of brown trout in autumn (October – November) lasted 22, 24, and 27 days respectively in the seasons 2002–2004. In 2002, 187 fish were trapped, while the number of trapped spawners increased to 447 in 2003 and 2230 in 2004. Spawning males were significantly longer than females (PoC in the reservoir. The peak of spawning, in all three seasons, took place between 28 October and 3 November, and the river water temperature varied from 6 to 8oC. The spawning in 2002 was more nocturnal (between 8:00 p.m. to 6:00 a.m.) than diurnal (P<0.01) and the diel activity showed the multimodal distribution. There were no large or significant differences between the diurnal and nocturnal migrations in 2003 and 2004. Single environmental variables and their interaction were significantly related to the spawning migration only in 2003 and 2004 (P<0.001).