It has been documented that ingestion of lead sinkers, jigs and other fishing tackle can injure or kill birds including loons and eagles. Here are some links from the Maine Audubon Society: http://maineaudubon.org/wp-content/uploads/2013/03/fact-sheet-about-lead.pdf
Here is most recent Maine’s Department of Inland Fish & Wildlife interpretation on the use a sale of lead sinkers:
Lead Sinker Law/Interpretation
1) The Department will interpret the definition of lead sinker to include any tackle that is permanently manufactured to the lead itself. When measuring for a minimum of 2.5 inches, the manufactured tackle will be included in the measurement. This will not include any additional items that have been added to the original manufacturing device.
2) Please read the manufacturer’s label carefully to determine the weight of the lead sinker. If the lead is manufactured as part of other fishing tackle, the entire piece of equipment needs to be more than 1 ounce in weight.
3) The definition of a lead sinker DOES NOT include artificial lures, weighted line, weighted flies or jig heads.
4) If a lead sinker is over 2.5 inches in length or it weighs over 1 ounce or both it is legal to use and sell or offer for sale.
5) We will interpret the law to mean that it applies to Inland Waters NOT Tidal Waters.
6) If a sinker contains any amount of lead, it will be considered illegal if it doesn’t meet the length and weight requirements.
Reminder: Currently the law only prohibits the use and sale of lead sinkers that do not meet the length and/or weight requirements. The sale of bare lead jigs and use of bare lead jigs not meeting the length and/or weight requirements is currently legal but will be prohibited in September of 2016 and September 2017 respectively.
8) If you have additional questions relating to this topic feel free to look at Maine Audubon’s website at: http://maineaudubon.org/wildlife-habitat/legislative-action/loons/