It was more than 25 years ago that lead poisoning was first identified as a major cause of morbidity and mortality for Common Loons in Maine and a number of other states. Early studies documented that nearly all lead poisoning resulted from ingestion of fishing gear. Loons may catch fish with lead sinkers and jigs attached, or pick up lead sinkers and jigs while ingesting pebbles from lake bottoms to help them digest their food. Loons appear to die relatively quickly after ingesting even one small lead object.
This three-year project being led by BRI’s wildlife veterinarians will determine the frequency of lead poisoning in Maine’s Common Loons and help assess the effectiveness of Maine’s new laws limiting the sale and use of certain types of lead fishing gear in fresh water.
In 2002, Maine enacted legislation aimed at protecting loons from lead poisoning, but the law proved too narrow in scope, and significant loon mortalities from lead continued. In an effort to remedy this, a successful bill was introduced to the Maine State Legislature in 2013. The new law strengthens the ban on lead sinkers to include both the sale and use of lead sinkers and includes a larger range of sizes than earlier legislation, banning sinkers weighing up to one ounce. The statute also bans the use and sale of bare lead-headed jigs two-and-a-half inches long or less, with a phased-in ban on the sale of those jigs beginning in September 2016 and on their use beginning in September 2017.
1.) Analyze and Expand the Long-term Dataset
For more than 25 years, dead Common Loons from Maine have been examined by Dr. Mark Pokras at Tufts Cummings School of Veterinary Medicine. This long-term dataset gives us a solid basis for comparison as the new legislation takes effect.
2.) Examine Common Loon Cadavers to Determine Cause of Death
Cadavers of Common Loons that die in Maine will be collected for examination. A comprehensive post-mortem (necropsy) examination will then be performed, and any fishing gear present in loons’ digestive tracts will be recovered, measured, and tested for the presence of lead. All recovered lead objects will be carefully documented and saved for future reference. Body fluids and/or tissues will be tested to determine lead levels. Other pathologies or causes of mortality will also be documented.
3.) Assess the Effectiveness Maine’s New Lead Fishing Gear Regulations
By quantifying new cases of lead poisoning from fishing gear in Common Loons, documenting the specific types of fishing gear that cause lead poisoning, and comparing these new findings to previous data on lead poisoning in loons in Maine over the past 25 years, we can begin to assess the effectiveness of the new legislation, angler compliance with these regulations, and the need for additional law enforcement and/or educational efforts.
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