Prey size selection of the Eurasian Otter,<i>Lutra lutra</i>(Linnaeus, 1758), at the Jajrood River, Iran

Abstract Eurasian Otters, Lutra lutra (Linnaeus, 1758), prey at the River Jajrood, east of Tehran, generally on fish between 3 and 21 cm in length, but the size range varied with different species and at different sites. The length of Alburnoides bipunctatus in the diet correlates with the length of fish found in the river, but a similar correlation is not found regarding Leucuscus cephalus and Capoeta spp. Otters appear to select these two species according to their size: L. cephalus and Capoeta spp. with a size between 9 and 15 cm and A. bipunctatus with a size between 3 and 9 cm. At site 2, a significant correlation was found between the length of A. bipunctatus in the diet and in the river, but there was no similar correlation for L. cephalus and Capoeta spp. As at site 1, otters appear to select L. cephalus and Capoeta spp. according to their length. At site 3, finally, we found a significant correlation between the length of A. bipunctatus and L. cephalus in the diet and in the river, but not in Capoeta spp. These results emphasise the diverse spectrum of the diet of the Otter in Iran. The differences between the three sites on the same river suggest that the Otter preys opportunistically.