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Plant-chomping fish clear canal stretch By WENDY SIPOREN TALENT -- Somewhere in the green murky depths of the irrigation canal flowing from Ashland to Talent are 151 hungry fish eating their way into the history books as the first in the state to be used to control weeds in an irrigation canal. "We put the fish in on June 18 and haven't seen one since then," said Hollie Cannon, Talent Irrigation District manager. Just two weeks into the experiment, the only signs of the fish are bits of plants floating on the surface, he said. The district hopes the Asian grass carp, imported from a fish farm in Arkansas, will prove to be an effective alternative to chemical herbicides in destroying the summer build-up of aquatic weeds that slow water flow and clog irrigators' pumps and sprinklers. "We want to determine how effective they are ... how cost effective and really what the hassle factor is," said Cannon. The fish are making their home in the same three-mile stretch of canal from which the herbicide acrolein spilled in 1996, killing an estimated 92,000 infant steelhead in Bear Creek. The spill forced TID to begin looking for alternatives to chemical weed control and after a preliminary study, the grass carp emerged as the best option. Except for a small private pond, TID's experiment is the first under the Oregon Department of Fish and Wildlife's new policy of allowing the non-native fish into the state under strict conditions. Biologists are concerned the fish -- which can consume up to three times their weight each day -- might out-compete native species for food if they were to escape the confines of the canal. When the carp were introduced to Devil's Lake near Lincoln City in 1986, the fish wiped out most of the vegetation and two other non-native species that depended on it for habitat. In addition to the state requirement that the fish be sterile and fenced-in, the district has implanted a small computer chip in each fish so individuals can be tracked throughout the study period. TID will submit its first report to the state this fall after the fish are recaptured and placed in a winter holding pond outside of the floodplain. ODFW fish biologist Mike Evenson says he expects some fish to be missing, most likely victims of a natural predator such as an osprey, raccoon or otter. "We're not sure quite what the potential (is) for adverse impacts in the Rogue basin," said Evenson. "The cautious approach is to make sure they are sterile ... and minimize the risk of them getting out." The U.S. Bureau of Reclamation will match $25,000 of the district's funds for the carp experiment, with the hopes of applying what is learned here to other areas in the state. Success is not guaranteed. Even with their reputation as aquatic goats, they are known to be picky eaters, said Evenson. "They either don't control them well or they wipe them out completely," he said. The canal has been divided into two study sections with different densities so that it can be determined just how many fish it takes to control the vegetation without them running out of food. Southern Oregon University professor Mike Parker and two biology students will be monitoring the fish over the summer. Use of the carp is also limited by the size of the irrigation canal, he said. Further on in the system, the ditch gets smaller, making the fish more vulnerable to predators. "They won't totally replace it (herbicide use)," said Cannon. "In the long term, the grass carp is just one tool in our tool belt to control weeds." Mail Tribune Copyright � The Mail Tribune 1999, Medford, Oregon USA