BIOLOGICAL CONTROLS used in California
Two type of biological control agents have been used in limited situations to control aquatic weeds in California.
The triploid grass carp (Ctenophyllum idealla) will consume filamentous algae and most submersed aquatic plants. (The triploid grass carp are functionally sterile and will not reproduce.) However, because it is a non-native species, its use is currently restricted to three counties in southern California. Contact the California Department of Fish & Game for permitting requirements.
In the early 1980's a weevil was introduced into the Sacramento-San Joaquin Delta for control of water hyacinths. However, there is little evidence that the weevils have had much impact, apparently due to difficulty with surviving the low winter temperatures which may occur in this region.