Wyoming became the last state in the lower 48 to warn about possibly unhealthy levels of mercury in fish, advising anglers today to be cautious about eating some saltwater fish and fish taken from Big Horn, Seminoe and Pathfinder reservoirs.

"Eating fish with high amounts of mercury can cause health problems, especially in children," Timothy Ryan, environmental public health section chief with the state Department of Health, said.

"In general, Wyoming fish are low in mercury," Ryan said. "But we are recommending that women of childbearing age, pregnant women, nursing mothers and children under the age of 15 should eat more small Wyoming-caught fish and fewer large fish, and should avoid eating channel catfish, bass, sauger and walleye from certain waters."

Mike Stone, fisheries chief with the Wyoming Game and Fish Department, explained that the size of fish is a factor in mercury levels in the fish.

"The longer a fish lives the greater its chances of accumulating mercury in its tissues," Stone said in a joint news release issued by the state health and game agencies. "In general, fish that feed on other fish or bottom-feeders are also more likely to accumulate mercury."

State Game and Fish spokesman Erik Keszler said only Alaska has yet to issue a mercury advisory.

Mercury is a naturally occurring element that is distributed throughout the environment by both natural processes and human activities. High amounts of mercury can damage the human nervous system, particularly in developing fetuses.

Specifically, the agencies offer the following guidelines when consuming fish:

Women of childbearing age, pregnant women, nursing mothers and children under 15 are advised to consume no more than two meals per week of fish that are low in mercury. People in that group should not eat fish that are considered high in mercury.

For others, the agencies advise prudent consumption of fish low in mercury and no more than one to two meals per month of fish high in mercury.

Freshwater fish low in mercury include Wyoming-caught trout and farm-raised tilapia and catfish. Freshwater fish high in mercury include channel catfish, sauger, and walleye from Big Horn, Seminoe and Pathfinder reservoirs.

Specific recommendations are available on the state Department of Health's Web site at http://www.health.wyo.gov and are included in the 2008-09 Wyoming Fishing Regulations, which will be available Jan. 1.