Management of inland fisheries in shallow eutrophic, mesotrophic and oligotrophic lakes in China

Abstract

Optimizing fish yields in natural waters has long been the primary goal of lake management in China. Three different approaches that are used to increase fish yields are illustrated with reference to lakes on the Jiang Han Plain. In managing eutrophic lakes, fishes which can exploit the large biomass of phytoplankton, zooplankton, benthos and detritus are stocked. The management of mesotrophic macrophyte-dominated lakes involves stocking primarily herbivorous fish such as grass carp (Ctenopharyngodon ideila). Stocking densities of these herbivorous fish are estimated from the total biomass of vegetation in each lake. In managing oligotrophic shallow lakes with low primary productivity, the first step is to increase vegetation biomass in the shallower areas. The lakes are then stocked with herbivorous fishes which — through their consumption of macrophytes — increase rates of nutrient remineralization and enhance the growth of plankton and zoobenthos. The overall result has been an increase in total fish production from the three types of lake, and the management approaches applied to Jiang Han Plain Lakes are now being adopted more widely in China.