Scientific Name
Rutilus frisii
Common Name
Kutum
Biology
A semi-anadromous species which occurs in large brackish estuaries and their large, freshened plume waters, coastal lakes connected to rivers and lowland stretches of large rivers. Can tolerate salinities up to 7-12 ppt. Landlocked populations live in lakes or reservoirs. Larvae and early juveniles take zooplankton, algae and insect larvae as food while adults feed on molluscs, Rhithropanopeus crabs and other benthic invertebrates. Feeding ceases while migrating, spawning and overwintering. Breeds in small rivers or streams with heavy current on gravel bottom. Begins migration to rivers in second half of October (Black Sea, rarely in Caspian Sea). When rivers are covered with ice, spawning migration stops and continues when ice breaks up or even under ice in February-April. Spawns in April-May. Adults migrate back to estuaries to forage immediately after