Ingestion of just one lead sinker can poison a loon. Loons are poisoned when they ingest lead sinkers along with fish. The sinkers are ground up in the loon's stomach and the lead is absorbed into the blood and tissues, causing lead poisoning.
When fishermen lose lead sinkers through broken lines or other means loons can inadvertently eat them. Biologists discovered in a recent study that seven of 95 loons found dead in Minnesota had ingested lead objects and tested positive for lead poisoning.
Not only are loons affected; so are other waterfowl, such as the magnificent trumpeter swan we have worked so hard to reintroduce. Some waterfowl swallow lead when they scoop up pebbles from the bottom of a lake or river to help grind their food; others ingest lead by eating a fish "hook, line and sinker."
Bald eagles and osprey, which rely heavily on fish for food, are also susceptible to lead poisoning. It doesn't take much imagination to recognize that all wildlife is undoubtedly affected by the presence of lead in our air, land and water.
Like other "heavy metals," lead is toxic and, in sufficient quantities, has adverse affects on the nervous and reproductive systems of mammals and birds. An animal with lead poisoning will have physical and behavioral changes, including loss of balance, gasping, tremors and, in the case of birds, impaired ability to fly. Wildlife weakened by toxicity is also more vulnerable to predators and may have trouble feeding, mating or caring for its young. Weak and emaciated poisoned animals often die within two to three weeks after ingesting lead.
Between 1984 and 1990, 221 loons were collected from 18 northern and central counties in Minnesota. Night-lighting was used to capture 93 loons and 128 were found dead or dying. No loons were sacrificed for the purpose of the study.
Feathers of both live and dead birds were analyzed for total mercury. Livers of dead birds were analyzed for mercury and livers of birds necropsied that exhibited lesions characteristic of lead poisoning were additionally analyzed for lead. Seventeen percent of the necropsied birds died of lead poisoning.
Biologists have studied the effects of lead sinkers and jigs on water birds and birds of prey since the 1970s. In areas where loons breed lead poisoning from sinkers or jigs may account for up to 50 percent of the dead adult loons found by researchers.
Between 1980 and 1996 the Raptor Center reported lead poisoning in 138 of 650 eagles treated there. From 1996-99, 43 additional eagles were treated for the same. Most of the time the source of the lead cannot be detected, as the birds have cast the material out of their system. The Raptor Center reports there has been no reduction in lead poison of bald eagles despite the recent restrictions on lead gun shot for hunting waterfowl.
It's time to get the lead out!
A high incidence of lead poisoning in loons (57 percent) was found in a New England study. As a result, earlier this year Maine banned the use of lead sinkers and jigs that weigh less than an ounce and are smaller than an inch. Great Britain banned the use of lead sinkers in 1987. In Canada, it is illegal to use lead fishing sinkers and jigs in national parks and national wildlife areas. The U.S. Fish and Wildlife Service is also considering a ban on National Wildlife Refuges where loons and trumpeter swans breed.
The Minnesota DNR is encouraging anglers to replace the lead in their tackle boxes and on their fishing lines on a voluntary basis. There are currently many non-toxic sinker alternatives on the market made out of bismuth, tin, stainless steel, tungsten, ceramic, recycled glass and natural granite. Because weights of the different materials will vary you will have to experiment a bit to find what works best for your type of fishing. Don't be quick to jettison the new tackle. Be patient and all wildlife will benefit.
Ask your local bait and tackle store to stock environmentally-friendly unleaded sinkers. Two examples are Gremlin Green and Bullet Weights. Some major discount stores have made a special effort to increase the variety and supply of non-lead sinkers.
And remember: never throw old tackle into the water or on shore. Consider old lead sinkers and jigs as toxic and dispose of them at a proper household hazardous waste collection site.
To ensure that future generations continue to experience the sight of an eagle soaring or the sound of loon calling, we need to do more to safeguard the environment. Even if you don't go fishing, share this information with family and friends who do.
Just tell them to "Get the lead out!"
(Direct Source: Minnesota Office of Environmental Assistance, DNR Nongame Wildlife Program.)
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