Consequences of biomanipulation for fish and fisheries

The main goal of biomanipulation by fish reduction is not a change in the fish community but a change in the aquatic ecosystem. Fish reduction is a method to push the system in another state, usually a shift from algae domination to macrophyte domination. Intensive fish removal is done by one of the following methods: seining (the Netherlands, Germany, UK), trawling (Sweden, Finland), use of rotenone (Norway, USA, Poland) and stocking of piscivorous fish (USA, Germany). If circumstances allow it (reservoir, ponds) draining is combined with seining (the Netherlands, UK, Poland). The intensity and duration of fishing differs per case, but is quite important for the way the system changes. Fishing may be combined with stocking of predatory fish, mainly pike and pikeperch (or walleye)......