Management of invasive and nuisance aquatic weeds uses herbicides, mechanical removal, and biological control with variable welfare implications for non-target aquatic animals.
Aquatic weed management welfare depends entirely on method selection and application specificity. Broad-spectrum aquatic herbicides kill invertebrates and plant communities beyond the target weed, destroying the habitat and food base for fish and waterfowl. Mechanical dredging eliminates benthic communities that may take years to recover. Grass carp provide biological control without chemical use but can overconsume native vegetation needed by other species. The most welfare-positive approach combines manual removal in targeted areas, minimally toxic and species-specific herbicides where necessary, and prevention of re-introduction rather than repeated large-scale treatment.