Otter (Lutra lutra) diet related to abundance of fish in some Latvia's rivers
1999
Birzaks, J. (Latvian Fisheries Research Inst., Riga (Latvia)) | Ozolins, J. (State Forest Inventory Inst., Riga (Latvia)) | Ornicans, A. (State Environmental Inspection, Riga (Latvia))
Otter feeding in the Salaca River and in four of its tributaries was investigated by excrement analysis and compared with fish abundance estimated by electrofishing. Of the 27 fish species inhabiting the studied waterbodies, 22 were identified in otter diet. Fish biomass was not related to consumption by otters. Fast swimming pelagic and semi-pelagic species were less preyed upon. The bottom dwelling stone loach Noemacheilus barbatulus and bullhead Cottus gobio, which are widespread and abundant species in the studied waters, were the most important otter food items. Seasonal changes in otter diet were determined by studying the size structure of consumed fish. The largest fish were consumed in spring, but the proportion of fish up to 10 cm long in otter diet was usually about 70% of all eaten specimens.
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