Lead Shot and Sinkers Implicated in Fish, Wildlife Health
Millions of pounds of lead used in hunting, fishing, and shooting sports wind up in the environment each year and can threaten or kill wildlife, according to a new scientific report.
Although lead shot was banned for waterfowl hunting in 1991, its use in ammunition for upland hunting, shooting sports, and in fishing tackle remains common.
While noting that more information is needed on some aspects of the impact of lead on wildlife, the authors said that numerous studies already documented adverse effects to wildlife, especially waterbirds and scavenging species, like hawks and eagles. Lead exposure from ingested lead shot, bullets, and fishing sinkers also has been reported in reptiles, and studies near shooting ranges have shown evidence of lead poisoning in small mammals.
Frequently used upland hunting fields may have as much as 400,000 shot per acre. Individual shooting ranges may receive as much as 1.5 to 23 tons of lead shot and bullets annually, and outdoor shooting ranges overall may use more than 80,000 tons of lead shot and bullets each year.
Although precise estimates are not available for lead fishing tackle in the environment, about 4,382 tons of lead fishing sinkers are sold each year in the United States.
The most significant hazard to wildlife is through direct ingestion of spent lead shot and bullets, lost fishing sinkers and tackle, and related fragments, or through consumption of wounded or dead prey containing lead shot, bullets or fragments, emphasized U.S. Geological Survey contaminants experts Barnett Rattner and Chris Franson. The two scientists are lead authors of The Wildlife Society technical report and co-authors with five other experts of a recent Fisheries article on the same subject.
"Science is replete with evidence that ingestion of spent ammunition and fishing tackle can kill birds," Rattner said. "The magnitude of poisoning in some species such as waterfowl, eagles, California condors, swans and loons, is daunting. For this reason, on July 1, 2008, the state of California put restrictions on the use of lead ammunition in parts of the range of the endangered California condor because the element poses such a threat to this endangered species."
Although lead from spent ammunition and lost fishing tackle is not readily released into aquatic and terrestrial systems, under some environmental conditions it can slowly dissolve and enter groundwater, making it potentially hazardous for plants, animals, and perhaps even people if it enters waterbodies or is taken up in plant roots. For example, said Rattner, dissolved lead can result in lead contamination in groundwater near some shooting ranges and at heavily hunted sites, particularly those hunted year after year.
To obtain a copy of the technical review report, "Sources and Implications of Lead-Based Ammunition and Fishing Tackle on Natural Resources," visit www.wildlife.org. For a copy of the American Fisheries Society article on the known and potential impacts of lead in shooting and fishing, visit http://www.fisheries.org/afs/docs/fisheries/fisheries_3305.pdf .