September 2, 2013

Lead poisoning killing loons, necropsies show

A Bay State animal medical examiner is the main voice behind a Maine law banning lead fishing sinkers and jigs.

NORTH GRAFTON, Mass. - A loon was beached on Cobbossee Lake in Winthrop, Maine, a maggot-filled wing wound keeping it from flying or resisting capture from a game warden.

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Volunteer Julia Graham photographs a loon's wing, as she assists Mark Pokras last month in the necropsy room of the wildlife clinic at Tufts University's veterinary medical school in North Grafton, Mass.

Photos by Joe Phelan/Kennebec Journal

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Mark Pokras holds up a swab that shows that the fishing jig removed from a loon tests positive for lead.

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The gash was too deep and the skin around it too decayed to save the agonized, emaciated bird. It was euthanized at an avian clinic in Freedom, Maine.

Enter Mark Pokras, whose job it is to figure out why the bird was disabled in the first place.

Since 1987, the Tufts University professor of wildlife health has done necropsies on approximately 2,000 loons, nearly 500 of them from Maine.

The small necropsy room in a corner of a clinic at the university's veterinary medicine school, on a rural campus less than 10 miles east of Worcester, is a laboratory of the macabre.

One day in mid-August, rabbit, loon and turtle cadavers lay in a refrigerator awaiting examination, each of their deaths a mystery for Pokras, an animal medical examiner, to solve.

Maybe the wing wound means the loon was attacked by an eagle, Pokras wonders aloud. Loons are also known to fight, so maybe it's from a pointed beak, normally used to spear fish.

Then again, those could just be good stories.

"But that's what we do," Pokras said. "We make up stories and then we try and test them."

The necropsy is the test. And as the loons have piled up, a trend has emerged.

Though the Cobbossee bird wasn't affected, Pokras has discovered that lead poisoning is the leading cause of premature death in Maine loons, whose haunting wails are a fixture of summer life, their images adorning license plates and trinkets at tourist shops.

He was a main voice behind a law passed earlier this year by the Maine Legislature that banned lead fishing sinkers and jigs, identified as the major culprit behind poisoning.

The law will fully ban sale and use of the lead fishing gear weighing one ounce or less or measuring 2½ inches or less by 2017.

But with a loon population that has boomed since it was first counted 30 years ago, Maine sportsmen are split on the ban. Conservationists, though, say the boom isn't what it seems and loons are vulnerable.


In Pokras' necropsy room, Julia Graham, a 2012 graduate of Mount Holyoke College in South Hadley, Mass., applying to veterinary schools and volunteering to assist the professor, made the first cut into the Cobbossee Lake loon.

The blade was drawn just under the skin. Small feathers flew. The loon's subcutaneous fat was gone, suggesting a period of weakness and starvation before death.

After that, the sternum was removed, revealing the loon's organs. There was still fat around the heart, the last store to be depleted before loons starve to death in the wild, Pokras said.

Graham cut open the bird's trachea to check for signs of fungal infection, which can plague loons in the wild. There was no sign of that.

Next is a cut into the gizzard, the bird's specialized stomach. If a lead sinker or jig were there, it would likely be seen in an initial X-ray of the bird and pulled out at this step.

But the Cobbossee bird's gizzard was mostly normal, holding the pebbles loons dive down lake bottoms to swallow in order to help break down food in their digestive tract.

That's where breeding adults almost always pick up lead from fishing gear that has fallen to lake bottoms, Pokras said. Before the necropsy on the Maine loon, he pulled a lead jig head out of another loon's gizzard, that one from New Hampshire.

(Continued on page 2)

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Additional Photos

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Pokras holds the lead jig he removed in front of an X-ray of it inside the bird.


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