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To Counter Thirsty River Plants, Texas Turns to Hungry Carp

The Washington Post News (02/02/2003)

By Karin Bruillard

Texas authorities have spent years struggling to save the dehydrated Rio Grande from thirsty exotic plants that clog the river and absorb its waters -- and soon, they’ll deploy an unconventional new warrior in the battle: neutered fish.

During the coming weeks, officials will release into the river 25,000 to 50,000 genetically neutered grass carp -- called “triploid” for the extra set of chromosomes that renders them infertile -- in hopes the fish will devour invasive plants that suck up the Rio Grande’s waters.

Tangled aquatic plants such as hydrilla and water hyacinth have impeded the river’s flow and worsened conditions in drought-stricken South Texas. Hydrilla has been named one of the Nature Conservancy’s “Dirty Dozen” of nonnative plant and animal species. Because carp reproduce quickly, eat any vegetation that crosses their paths and present a risk to farmlands and native flora along the river, a team of Southwest Texas University biologists tested a preliminary team of the triploid carp last summer. The modified fish, which were equipped with radio tags so scientists could track their movements, performed perfectly, mowing down the insidious plants.

Biologist Tom Arsuffi said he is confident the sterile swimmers can help control the plants. “These guys are vegetarians and they like aquatic salads,” he said. “They’re very effective.”