Lower mercury levels found in Utah's ducks

Last year, Utah duck hunters were advised to avoid shooting northern shovelers or common goldeneye ducks because of higher-than-allowable mercury levels.

This year, leading up to the duck hunt, which starts Oct. 7, hunters are being told they can shoot but to stay on the conservative side.

Samples taken on ducks on Utah's marshes around the Great Salt Lake between October and February showed mercury levels well below EPA screening values.

While the ducks are safe to eat, officials are suggesting they be eaten sparingly.

In the case of the northern shovelers, adults are being advised to eat no more than two 8-ounce servings per month. Children, pregnant women and women who may become pregnant are advised to eat no more than one 4-ounce serving per month.

In the case of common goldeneye, adults are advised to eat no more than one 8-ounce serving per month, and children, pregnant women and women who may become pregnant should not eat common goldeneye taken on marshes around the Great Salt Lake.

The advisory also added a third duck to the list — cinnamon teal. The same guidelines placed on shovelers should also be followed for teal.

"Why the drop in mercury levels?" said Tom Aldrich, migratory bird manager for the Utah Division of Wildlife Resources. "That's a good question. I have several theories, but we'll have to complete more studies before we can give a definitive answer."

He explained that during the test, hundreds of thousands of clean birds or birds with low mercury levels migrated onto Utah's marshes, literally overshadowing those birds with higher levels.

"When you have half a million birds migrate in and then go out and sample, the average bird is certain to have less mercury," he added.

There's also the possibility that as the clean birds arrive, the "hot" birds migrate off the marshes.

"Otherwise, as the clean birds are coming in, the birds with higher levels are leaving, so you're more likely to test birds with lower levels," Aldrich explained.

It's a fact, too, in humans anyway, and most likely birds, that once foods containing mercury are no longer being eaten, the body naturally rids itself of half the mercury level every 60 days.