The Vadnais Lake Area Water Management Organization is continuing to see evidence of lead poisoning in trumpeter swans found dead on waters where lost fishing tackle lies in shallow areas.
In the latest case of a swan found dead Feb. 3 on Sucker Channel, pathologists at the University of Minnesota last week found a silver, metallic sinker inside the bird during a necropsy exam. A report from the university’s Veterinary Diagnostic Lab said internal lesions in the swan suggest lead toxicity. The suspicion of heavy metal poisoning likely will be confirmed next week, the report said.
Dawn Tanner, the conservation biologist for the watershed around Vadnais Heights, said this would be the fifth confirmed lead poisoning of a trumpeter swan in the area in the past 14 months. The same cause of death is suspected in eight other swan deaths in that time period, including an adult swan that died recently on East Vadnais Lake, she said. The bird was on thin ice and couldn’t be retrieved for testing.
Tanner’s work is relevant to the Minnesota Pollution Control Agency’s attempt to reduce the use of lead sinkers and jigs. The agency is ready to roll out a $1.2 million public awareness campaign to encourage Minnesotans to voluntarily switch to small nontoxic fishing jigs and sinkers. Federal funding for the three-year program has hit a snag at the Legislature, but it’s not expected to thwart the initiative.
“These deaths are completely unnecessary because nonlead alternatives are available and inexpensive,’’ Tanner said.
The education effort aims to reduce the annual mortality of loons and other waterfowl due to lead poisoning. As many as 200 to 300 loons are estimated to die of lead poisoning every year in Minnesota. The birds encounter the lead pieces on lake bottoms while ingesting grit necessary for them to digest food.
Tanner said she responded to 11 swan deaths in her watershed last year. Many of the birds were found emaciated, and none showed signs of outward injuries. Four of the birds were suitable for post-mortem examination at the university and all four were declared victims of lead toxicosis, according to reports from Dr. Arno Wuenschmann, a veterinary pathologist.
Last fall, Tanner organized a group of university students to test sediment in a shallow, high-use fishing area in the watershed. The testing recorded numerous examples of fishing tackle scrambled with pebbles in samples of sediment.