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Anglers need to pay attention to a couple of new species and add a major fishery if they plan to eat what they catch in Utah.
Utah's Mercury Fish Consumption Advisory List grew Tuesday with a few additions:
Smallmouth bass from Flaming Gorge Reservoir, which straddles the Utah/Wyoming border, showed elevated levels of mercury in samples collected. The positive test is the first for the Utah side of the lake; tests in Wyoming have already found contaminated fish.
Tiger muskie, a warmwater species recently added to Joes Valley Reservoir, also tested positive.
And smallmouth bass at Upper Enterprise Reservoir also were added to the list of contaminated fish.
Joes Valley and Upper Enterprise both already had fish on the warning list.
Utah now has 27 waterways and 14 fish species on the consumption advisory list with a potential for more.
"We sample as many waters and species as we can and run them through the Department of Environmental Quality. We can't afford to run unlimited samples so we try to look at the most popular fisheries," said Roger Wilson, chief of aquatics for the Utah Division of Wildlife Resources. "It is a concern, of course, but only 10 percent of the waters we have sampled have shown elevated levels of mercury."
Though mercury occurs naturally in the environment, it is believed additional mercury can build up from air particulates and upstream mining activities.
The toxic form, methylmercury, accumulates in nerves and muscles and is passed up the food chain. Fish that eat other fish or foods with methylmercury inherit the toxin. Predatory fish, like smallmouth bass and tiger muskie, feed predominantly on other fish and crayfish.
People who eat those fish also accumulate the toxic form of mercury in their bodies.
The amount of fish people can eat varies on the species, the reservoir they come from and the people eating them.
For example, pregnant women and children under age 6 should limit their intake of smallmouth bass from Flaming Gorge to one 4-ounce meal per month. Women of child-bearing age and children ages 6 to 16 years old should only eat two 8-ounce servings a month. And women past child-bearing age and men over 16 years old can have as many as seven 8-ounce meals.
But pregnant women and children under age 6 should not eat tiger muskie from Joes Valley or smallmouth bass from Upper Enterprise Reservoir because the fish have more mercury in them.
Ratings for the new species added to the list and all the others can be found at Utah's Mercury Fish Consumption Advisory List website.
Health officials point out that the advisories are based on long-term consumption and are not tied to eating fish occasionally. Fish can be an important part of a healthy diet.
Smallmouth bass and tiger muskie, while popular sport fish, are not species many people eat in Utah.
"Smallmouth bass are the least targeted species by anglers on Flaming Gorge," said Ryan Mosley, Flaming Gorge Project Leader for the Utah Division of Wildlife Resources.
Wyoming listed consumption advisories for fish on its side of Flaming Gorge in December of 2012, with special note that burbot longer than 30 inches should not be eaten by pregnant women or children.
Mosley said Utah's fish have been tested several times since 2006. Smallmouth samples collected in the summer of 2013 proved interesting enough for further testing. Smallmouth bass caught this summer showed the elevated levels of mercury, but no other species were above the acceptable mercury level.
"It doesn't make a whole lot of sense," Mosley said. "We tested the same species in the same places and the same sizes. It is weird that they wouldn't be high and then they were."
Also on Tuesday, the advisory for consumption of striped bass in Lake Powell was updated. Striped bass in Lake Powell were added to the mercury list in 2012. But new tests results showed stripers collected north of Dangling Rope Marina came back below the level of concern. A consumption advisory remains for striped bass south of Dangling Rope.
"We took a fairly sizable sample and we are not seeing the elevated levels up-lake," Wilson said. "Lake Powell is massive and Dangling Rope is a good dividing line."
Twitter: @BrettPrettyman