Jon Davids' summer job is driving an enormous inflatable largemouth bass across the country in a white van.

Davids, a student from Lynn, Mass., is with the "Clear the Air" campaign created by a nonprofit organization called the U.S. Public Interest Research Group. He brought the giant fish to Bismarck's Sertoma Park on Thursday to be part of a presentation by groups concerned about the levels of mercury in the state's fish. The groups are calling on North Dakota's congressional delegation to oppose what they call the Bush administration's proposal to weaken mercury emission rules for power plants.

Steve Van Dyke, spokesman for Partners for Affordable Energy, a coalition that promotes coal-based electricity, called that assertion misleading.

There are no mercury standards at present, Van Dyke said. The Bush administration is trying to establish some, he said, and the Environmental Protection Agency is taking comments this summer as it looks at three different standards, he said.

Technology exists which could eliminate 90 percent of mercury emissions, said Mary Mitchell of the Missouri Valley Chapter of the Dakota Resource Council, another sponsor of the presentation.

Van Dyke's group disagrees.

"There is no control technology that works on large-scale power plants," he said. At present, more than $25 million is being spent researching mercury capture techniques, he said.

North Dakota's coal-fired power plants release 2,000 pounds of mercury into the air each year, which makes its way into the water supply and from there to fish and then to people, said Jonathan Bry, of Bismarck, chairman of the Dakota Chapter of the Sierra Club.

Mercury, as a heavy metal, is a neurotoxin particularly dangerous for young children and pregnant women, Bry said. He said that mercury accumulates in fish, particularly bass; as a fisherman himself, he said he keeps only medium-sized fish, not the larger, older ones.

According to the presentation sponsors, mercury may cause learning disabilities, developmental delays and other problems in children, and that mercury is passed through a mother's placenta to her unborn child, and to babies through breast milk.

The North Dakota Department of Health has issued a warning and guidelines for a number of fish commonly caught in the state, recommending meal limits on them because of mercury concerns, he said.

Those guides are available at most places where fishing licenses are sold, said Mike Ell, environmental scientist at the Department of Health, as well as the department's Web site at http://www.health.state.nd.us/wq. The guidelines were published in 2003 and were based on data collected over a 7-10 year period, he said.

Carmen Hoffner of Bismarck, a member of the Missouri Valley Resource Council, said that coal-fired power plants are the biggest source of mercury both nationally and in North Dakota, and that the Bush administration is pushing for weaker rules that the Environmental Protection Agency is developing, including permitting trading of pollution control credits by power plants. This trading could result in areas with no reductions in mercury at all, she said.

"This is not the best we can do," she said.

Van Dyke said that flume studies show that most of the mercury that settles in North Dakota is not locally generated, but comes from overseas, mainly Asia.

About 30 day-care children attended the program Thursday, had their picture taken with the big fish, and colored and signed pages that will be sent to Sen. Byron Dorgan, D-N.D., Sen. Kent Conrad, D-N.D., and Rep. Earl s, D-N.D., Hoffner said.