Silver carp
Hypophthalmichthys molitrix Val. have been stocked in Lake Kinneret, Israel, since 1969. From 1972 to 1981, 11 × 10
6 fingerlings were introduced into the lake. Total silver carp catch however was only 642 during this period, resulting in a progressive increase in the silver carp population.
Silver carp feed mostly on phytoplankton from February through August. From September to January, sampled gut contents contained predominantly zooplankton. Indices of electrivity for zooplankton were positive from September to December, negative during January to August and vice versa for phytoplankton.
Predation pressure of planktivorous fish on zooplankton in Lake Kinneret has been intensified recently. It is likely that accumulation of silver carp in the lake supported this process.
Silver carp compete with commercially valuable native fish species by feeding on the same zooplankton resources during summer and fall. Additionally, the grazing population of microcrustaceans is reduced at the time it is needed to prevent microalgae blooms.
Market demands for silver carp are low, catchability of this fish is poor and it can be cultured efficiently in ponds. Consequently it is recommended to stop the stocking of silver carp in Lake Kinneret.
Keywords silver carp - natural food - Lake Kinneret - management