Biological Control of Aquatic Weeds: The Efficacy of Hybrid Grass Carp in Two Southern California Irrigation Canals

摘要

The use of hybrid grass carp (a result of crossbreeding female grass carp, Ctenopharyngodon idella, with male bighead carp, Aristichthys nobilis) for aquatic weed control in irrigation canals was evaluated in a 3-year cooperative study. Studies were conducted in both a small lateral and a large delivery canal in southern California. Data were collected on macrophyte distribution, biomass, stem length and density, tuber density, and soil composition. During the 1980 growing season, field techniques were developed and baseline measurements were made. Hybrids were stocked from June to September 1981, at rates from 56 to 296 kilograms per hectare. During the summer of 1982, all test sections showed trends of lower plant biomass in stocked areas than in corresponding control areas.