Lead Fishing Weights and Loons
The Problem
The common loon, charismatic symbol of our northern lakes, faces a variety of threats linked to human activity. Among them is lead poisoning from the ingestion of lead fishing weights. Since 1987 nearly half of the adult loons found dead or moribund on New England freshwater lakes submitted to the Tufts University Wildlife Clinic have been diagnosed with lead poisoning. In New York, lead poisoning has accounted for about 30% of loon mortality documented, excluding mass mortalities from type E botulism on Lake Erie in recent years.
Lead sinkers
Lead weighted Lures
The lead fishing weights ingested by loons can be categorized as sinkers (weights affixed to fishing line) or weighted lures (mostly weighted hooks, i.e. jigs). Both sinkers and weighted lures are frequently lost when snagged on rocks, fallen trees, or other submerged hazards. They are also sometimes simply dropped or spilled while handling and not recovered. Why loons consume these objects has not been studied but the reasons are likely multiple. It has been proposed that loons mistake lost sinkers for the small stones they regularly ingest to help grind fish bones and crustacean shell in their muscular stomach. However, as hooks, brass swivels and pieces of monofilament often accompany sinker remains in loon stomachs, it seems more plausible that sinkers are incidentally ingested when loons swallow minnows or crayfish attached to rigs that have been lost. Finally, and very importantly, lead-weighted lures resemble prey items and are probably mistaken for such by loons. The fact that the lead objects we have found in loons in New York have been most frequently of lure origin than sinker in origin would also seem to support the ingestion of sinkers incidental to bait consumption hypothesis.
Remains of Lead weight in
loon gizzard
Some waterfowl and other waterbirds may also ingest fishing weights. Lead poisoning has been shown to be an important mortality factor in swans in some locations. Examination of dead waterfowl from New York's Finger Lakes during an outbreak of duck viral enteritis in 1994 revealed a surprisingly high incidence (7/15) of lead weights in redhead ducks.
Regulatory Action
Lead fishing weights from loon stomachs
In recognition of the threat to loons and other birds, the sale or use of lead fishing weights has been variably restricted in recent years in a number of locations in the United States and Canada. New Hampshire prohibits the use and sale of lead jigs and sinkers with a total weight of one ounce or less. Maine and, most recently, New York have banned the sale of lead sinkers weighing less than half of an ounce. The use of lead sinkers and jigs weighing less than 50 grams is prohibited in Canadian national parks and national wildlife areas. Lead sinkers are currently prohibited in three national wildlife refuges in the western United States.
Alternatives to Lead
Alternatives to lead now available in sinkers and jigs currently include steel, bismuth, tin, tungsten, alloys of these metals, and metal/plastic or metal/ceramic combinations. The performance and availability of these products has improved rapidly. A good introduction to these products and their manufacturers can be obtained from the Minnesota Office of Environmental Assistance.
Caution: There are also fishing weights made from zinc. These should be avoided as zinc is sufficiently toxic by ingestion that it could, like lead, threaten loons and other aquatic birds.
What You Can Do
Stop using lead tackle, including lead-weighted jigs and other lead-weighted lures. Dispose of the lead on community hazardous waste collection days, or turn in the lead tackle at businesses participating in the Adirondack Cooperative Loon Program's lead sinker exchange program.
Buy Lead-Free Tackle. Patronize retailers that stock the best assortment of lead-free tackle. Ask retailers to stock lead-free replacements for all weighted tackle products.
Recover Snagged Tackle as much as possible. Hooks, lures and monofilament are hazards to wildlife, whether or not you are using lead.
Encourage fellow anglers to follow your example.
Final Thought
The toxicity of lead to animals is well known. We have used this metal extensively for a variety of purposes, some of which have led to toxic consequences for ourselves and wildlife. In the last few decades, however, we have made significant progress in reducing lead releases to the environment by restricting uses in paint, gasoline, pesticides and other products, promoting battery recycling, and prohibiting the use of lead shot in waterfowl hunting. Not long ago, hundreds of thousands of waterfowl died every year from the ingestion of lead shotgun pellets deposited in wetlands across North America. Since the nationwide ban on lead shot use for waterfowl in 1991, lead poisoning in waterfowl has been greatly reduced. With your help we can take another step on getting lead out of the environment. Loons, other wildlife, and ourselves will be the better for it.
Learn More about Loons:
McIntyre, Judith W. 1988. The Common Loon - Spirit of Northern Lakes. University of Minnesota Press, Minneapolis, Minnesota.
Klein, Tom 1985. Loon Magic. Paper Birch Press, Ashland, Wisconsin.
