Lead Shot And Sinkers: Weighty Implications For Fish And Wildlife
Health

ScienceDaily (July 16, 2008) — 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.

Lead is a metal with no known beneficial role in biological systems,
and its use in gasoline, paint, pesticides, and solder in food cans
has nearly been eliminated. 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 USGS
contaminants experts Drs. Barnett Rattner and Chris Franson. The two
scientists are lead authors of The Wildlife Society (TWS) 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."
Lead poisoning causes behavioral, physiological, and biochemical
effects, and often death. The rate of mortality is high enough to
affect the populations of some wildlife species. Although fish ingest
sinkers, jigs, and hooks, mortality in fish seems to be related to
injury, blood loss, exposure to air and exhaustion rather than the
lead toxicity that affects warm-blooded 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 water bodies 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.

Research on lead poisoning related to spent ammunition and lost
fishing tackle has been focused on bird species, with at least two
studies indicating that the ban on the use of lead shot for hunting
waterfowl in North America has been successful in reducing lead
exposure in waterfowl, the report said. The authors found that upland
game — such as doves and quail — and scavenging birds — such as
vultures and eagles — continue to be exposed to lead shot, putting
some populations (condors in particular) at risk of lead poisoning.

Some states have limited the use of lead shot in upland areas to
minimize such effects, and others are considering such restrictions.
Environmentally safe alternatives to lead shot and sinkers exist and
are available in North America and elsewhere, but use of these
alternatives is not widespread, according to the report.

The authors of the report concluded that a better understanding of the
toxicity and amount of lead poisoning in reptiles and aquatic birds
related to fishing tackle is needed, as well as more information on
the hazards of spent ammunition and mobilized lead at or near shooting
ranges. In addition, the authors suggested that a more detailed
knowledge of how lead shot and fishing tackle specifically affect
wildlife here and in other countries is essential, as well as studies
that evaluate the effects on wildlife health and ecosystems of
regulations restricting the amount of lead ammunition and lead fishing
tackle.

This technical review was authored by contaminant experts at the
request of TWS and the American Fisheries Society (AFS). Such reviews
synthesize available information and research on a particular topic.
In this case, TWS and AFS sought to address the scientific data on the
hazard and risk of lead in hunting, shooting sports, and fishing
activities to fulfill their conservation missions.

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Adapted from materials provided by United States Geological Survey.

United States Geological Survey (2008, July 16). Lead Shot And
Sinkers: Weighty Implications For Fish And Wildlife Health.
ScienceDaily. Retrieved July 17, 2008, from http://www.sciencedaily.com­
/releases/2008/07/080711125733.htm

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