NORWAY – A senior biologist with FPL Energy Hydro of Lewiston said a highly toxic compound of the heavy metal mercury is increasing by 10 percent annually in Maine loons.

Bill Hanson addressed about 40 people Wednesday night at a meeting of Mollyockett Chapter of Trout Unlimited in Norway, saying biologists are looking for methylmercury in loons, bald eagles and fish.

Loons are the best indicator for tracking mercury levels because they faithfully return to the same spot in the same lake for 25 years to breed.

“Loons only eat fish of that cove on that lake. They don’t fly to another lake and bring fish back,” Hanson said.

According to the Maine Department of Environmental Protection, mercury levels in Maine fish, loons and eagles are among the highest in North America.

Found naturally in small amounts in oceans, rocks and soils, large amounts of mercury are becoming airborne through burning coal, oil, wood, or natural gas as fuel, incinerating mercury-laden garbage, and through industrial production processes that use the heavy metal.

“We’re at the end of the tailpipe. It’s coming over from the middle of the country, and it’s discouraging. Mercury is quickly becoming a huge issue,” Hanson said.

When mercury gets burned out of coal, he said, it vaporizes and returns to earth in precipitation. When airborne mercury particles land near water, little microbes in mud latch onto them.

The bacteria then excrete methylmercury, and it attaches itself to plankton.

“A little minnow eats tons of plankton, a bigger fish eats 100 minnows, and an adult loon eats 700 pounds of fish in the summer. Mercury’s bad stuff,” Hanson said.

Mercury is additionally believed to be the culprit that’s keeping Maine’s bald eagle population from rebounding, Hanson said.

It may also be a factor in disappearances of loons.

In New Hampshire, loons are threatened; in Maine, they’re not. But, Hanson said, Maine loons contain higher concentrations of methylmercury.

Several loons tested in Chain of Ponds above Eustis, and Aziscohos, Flagstaff and Parmachenee lakes were found to have high concentrations of methylmercury.

“Little Lobster Lake is off the charts,” Hanson said of the Piscataquis County water body in Lobster Township east of upper Moosehead Lake.

Biologists believe that high mercury levels have decreased egg-laying capability and hatchability in loons, altered parental investment and chick behavior, decreased juvenile survival, and reduced fitness in adults and juveniles, and lifetime reproductive success.

According to a 1998-2000 study by the BioDiversity Research Institute for the Maine Department of Environmental Protection, 30 percent of the breeding loon population in Maine is estimated to be at risk, while 46 percent of the eggs laid are potentially impacted.

Mercury pollution, the study states, has created an aquatic landscape that is not sustainable for the common loon in Maine.

Once the non-breeding or buffer population is exhausted, the occupancy of established territories will shrink, and “it will be more obvious that loon populations are declining,” the report states.

But, reversing the decline, Hanson said, will require drastic and potentially expensive efforts.

“Our hope is to stay ahead of the problem,” Hanson said.