Lead poisoning from ingestion of fishing gear: A review

Abstract

Many publications have investigated the ingestion and toxicity of metallic lead from hunting and the shooting sports. However, there is limited literature on toxicity associated with the ingestion of lead fishing weights, despite our knowledge of damage caused to many species from entanglement in lines, nets, and fish-hooks. This paper surveys current knowledge of species poisoned by ingestion of lead fishing gear and the types of gear that have been implicated. We review the impacts of lead fishing tackle on wildlife species and human health and describe the efficacy of efforts to reduce the use of lead tackle through voluntary, educational, and regulatory approaches to encourage adoption of non-toxic fishing gear. The authors emphasize the need for further research and policy initiatives to deal with this serious problem.

Full text

LEAD USE IN HUNTING
Lead poisoning from ingestion of fishing gear: A review
Tiffany Grade, Pamela Campbell, Thomas Cooley, Michelle Kneeland,
Elaine Leslie, Brooke MacDonald, Julie Melotti, Joseph Okoniewski,
Elizabeth Jane Parmley, Cyndi Perry, Harry Vogel, Mark Pokras
Received: 3 December 2018 / Revised: 26 February 2019 / Accepted: 1 April 2019
Abstract Many publications have investigated the
ingestion and toxicity of metallic lead from hunting and
the shooting sports. However, there is limited literature on
toxicity associated with the ingestion of lead fishing
weights, despite our knowledge of damage caused to
many species from entanglement in lines, nets, and fish-
hooks. This paper surveys current knowledge of species
poisoned by ingestion of lead fishing gear and the types
of gear that have been implicated. We review the impacts
of lead fishing tackle on wildlife species and human
health and describe the efficacy of efforts to reduce the
use of lead tackle through voluntary, educational, and
regulatory approaches to encourage adoption of non-toxic
fishing gear. The authors emphasize the need for further
research and policy initiatives to deal with this serious
problem.
Keywords Jig Loon Lure Sinker Swan Waterbird
INTRODUCTION
Lead has been used for fishing weights since ancient times
(Galili et al. 2013; Tyrrell 2015). Such weights are used to
sink nets and fishing lines below the water’s surface and
also to add mass to lines and nets to facilitate casting.
Nomenclature for the weights used in fishing tackle varies
regionally but includes such objects as split shot, sinkers,
jigs, lures, worm weights and trolling weights (Schroeder
2010).
Toxicity from ingested lead fishing tackle has been doc-
umented in many species including humans (Table 1; Blus
1994; Perry 1994; Scheuhammer and Norris 1995; Anderson
et al. 2000; Scheuhammer et al. 2003; Franson et al. 2003). It
is well documented as a leading cause of death for common
loons (great northern divers, Gavia immer) (Pokras and
Chafel 1992; Stone and Okoniewski 2001; Sidor et al. 2003;
Strom et al. 2009; Grade et al. 2018) and swans (Cygnus spp)
(Sears and Hunt 1991; Kirby et al. 1994; Newth et al. 2016).
The purpose of this paper is to review current knowl-
edge of the impact of lead fishing tackle on wildlife species
and human health and to investigate the efficacy of efforts
to reduce the use of lead tackle through voluntary and
regulatory approaches. After reviewing estimates of rates
of loss of lead tackle into the environment, we examine the
impact of lead tackle on wildlife, using swan species and
common loons as case studies. We then review the sub-
lethal impacts of lead tackle on wildlife and human health
before examining voluntary and regulatory efforts to limit
the use of lead tackle. We conclude by calling for increased
and more coordinated documentation of wildlife ingestion
of lead tackle and suggest approaches to reduce the input of
lead tackle into the environment.
In conducting our review of current literature on lead
poisoning from fishing gear, we searched initially for the
following keywords in Web of Science, Google Scholar,
PubMed, and SORA: ‘avian’ or ‘lead poisoning’, ‘lead
toxicosis’ and ‘fishing’, ‘fishing gear’, ‘sinker’. This initial
search allowed us to determine the most commonly
reported endpoints. We then conducted subsequent sear-
ches with ‘avian’ or ‘bird’ and ‘sinker’ or ‘weight’ and
each endpoint of interest. References from the publications
collected from these searches were also collected until we
were satisfied that all relevant references were included.
We included both field and experimental studies that
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s13280-019-01179-w) contains sup-
plementary material, which is available to authorized users.
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https://doi.org/10.1007/s13280-019-01179-w

examined correlations between tissue or blood concentra-
tions of lead and endpoints of interest. Although we did not
set a limitation to how far back we went in time, we only
collected articles that were available electronically via the
portals listed above.
LOSS OF LEAD FISHING TACKLE
By their very nature, lead fishing weights are designed to
be used in aquatic environments where they can be irre-
trievably lost. This often occurs when the line to which
they are attached becomes caught or entangled and then
breaks or is cut. But it can also occur when larger fish break
the line, or when smaller lead tackle (e.g., split shot) are
inadvertently dropped and not retrieved.
Studies have documented that significant amounts of
lead can be deposited into lakes and rivers by the loss of
lead fishing tackle. Although not differentiating among the
various types of lead fishing weights, Duerr (1999) found,
‘‘Along heavily fished shorelines, we found an average of
0.05 sinkers/sqm…. Anglers lost, on average, 0.2 sinkers…
per hour spent fishing.’’ Twiss and Thomas (1998) stated,
‘‘An estimated average of 125 to 187 million lead sinkers
are deposited in Canadian waters annually, with about half
in Ontario.’’ A recent Canadian study (ECCC 2018) stated,
‘‘An average Canadian angler can lose 11 to 15 jigs and
sinkers per year while fishing due to snags and other rea-
sons. This adds up to about 460 metric tons of lead jigs and
sinkers lost every year into Canada’s lakes and waterways.
This represents the most significant source of lead releases
into Canadian waters.’’ Radomski et al. (2006) estimated
that during a single walleye (Sander vitreus) fishing season,
one metric ton of lead fishing weights entered five Min-
nesota waterbodies. Scheuhammer et al. (2003) calculated
that approximately 4384 tons of lead fishing tackle were
lost each year in U.S. waterways, and Jacks et al. (2001)
reported that, in Sweden, 100–200 metric tons of lead
sinkers are estimated to be lost annually. Similarly, in
Great Britain, Birkhead (1982) reported an estimated
annual loss of 250 metric tons of fishing sinkers each year.
At local sites in Great Britain, studies reported [15 000
lead split shots lost per hectare annually, with anglers
losing 2–7 split shot sinkers per visit (Bell et al. 1985;
Forbes 1986; Cryer et al. 1987). Lloret et al. (2014) doc-
ument that lead fishing weights accounted for 36% of lost
fishing gear recovered from the seabed in a coastal
Mediterranean area.
LEAD FISHING GEAR INGESTION IN ANIMALS
To date, more than 30 species of birds have been docu-
mented to have ingested lead fishing tackle, along with 3
mammal and 2 reptile species (Table 1). It is estimated that
75 North American bird species may be at risk of lead
Table 1 Animals documented to ingest lead fishing gear (modified
from Perry 1994)
Avian species
Trumpeter swan, Cygnus buccinator
Mute swan, Cygnus olor
Tundra (whistling) swan, Cygnus columbianus
Whooper swan, Cygnus cygnus
Canada goose, Branta canadensis
Wood duck, Aix sponsa (Scheuhammer et al. 2003)
Mallard, Anas platyrhynchos
American black duck, Anas rubripes
Redhead, Aythya americana
Greater scaup, Aythya marila
White-winged scoter, Melanitta deglandi
Long-tailed duck, Clangula hyemalis (Schummer et al. 2011)
Red-breasted merganser, Mergus serrator
Common merganser, Mergus merganser
Great blue heron, Ardea herodias
Great egret, Ardea alba
Snowy egret, Egretta thula
Green heron, Butorides virescens (Scheuhammer et al. 2003)
Black-crowned night-heron, Nycticorax nycticorax (Franson
et al. 2003)
White ibis, Eudocimus albus
Double-crested cormorant, Phalacrocorax auritus
Sandhill crane, Antigone canadensis (Windingstad et al. 1984)
Brown pelican, Pelecanus occidentalis
American white pelican, Pelecanus erythrorhynchos
Northern gannet, Morus bassanus (Pokras, unpubl.)
Laughing gull, Leucophaeus atricilla
Herring gull, Larus argentatus
Royal tern, Thalasseus maximus (Scheuhammer et al. 2003)
Common loon, Gavia immer
Red-throated loon, Gavia stellata (Twiss 1997)
Little penguin, Eudyptula minor (Harrigan 2016)
Bald eagle, Haliaeetus leucocephalus
Great horned owl, Bubo virginianus (MI DNR, unpubl.)
Non-avian species
Humans, Homo sapiens (Mowad et al. 1998, St. Clair and
Benjamin 2008)
Domestic dog, Canis lupus familiaris
(Bengfort and Carithers 1976)
Harbor seal, Phoca vitulina (Zabka et al. 2006)
Snapping turtle, Chelydra serpentina (Borkowski 1997)
Painted turtle, Chrysemys picta (Scheuhammer et al. 2003)
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tackle ingestion due to their foraging behavior (US EPA
1994). However, documentation of the extent of lead tackle
ingestion both across and within species has been generally
poor, due to the difficulty of detecting lead-poisoned ani-
mals as well as limitations of funding and research prior-
ities. Regarding the former, Pain (1991) referred to the
‘‘invisibility’’ of waterfowl that have died from lead poi-
soning, because ailing birds tend to hide in thick vegetation
and carcasses are quickly scavenged. Large numbers of
birds generally do not die in a single location from lead,
also making carcasses less conspicuous (Franson and
Cliplef 1992; Newth et al. 2013). As a result, lead poi-
soning is likely underrepresented as a cause of mortality
among wildlife (Franson and Cliplef 1992; Franson et al.
2003; Strom et al. 2009; Newth et al. 2013; Grade et al.
2018). Due to the difficulties of detecting lead-poisoned
wildlife, lead tackle ingestion has been best documented in
high profile, charismatic, and intensively studied large
species such as swans and common loons. Because of this,
we use these species as case studies for the impact of lead
tackle ingestion on wildlife.
CASE STUDIES: LEAD TACKLE INGESTION
IN SWANS AND COMMON LOONS
Acquisition of lead tackle in swans and common
loons
Methods of ingestion of lead fishing tackle for loons and
swans vary from acquiring tackle from current fishing
activity to ingesting lost tackle as grit. For common loons
in New Hampshire, Grade et al. (2018) found a peak of
lead tackle mortalities in July and August, coinciding with
a peak of fishing activity, and that the majority of loons
that died from lead fishing tackle ingestion also had
ingested non-lead associated tackle (i.e., hooks, fishing
line, swivels, leaders). This evidence suggests that current
fishing activity (e.g., eating a fish that has ingested a lead
jig or sinker and broken the line, or striking at tackle or a
fish being retrieved by an angler) is a primary mechanism
by which loons ingest lead fishing tackle (Grade et al.
2018). This is in contrast to speculations in previous
studies (Pokras and Chafel 1992; Scheuhammer et al.
2003; Pokras et al. 2009; Haig et al. 2014). These studies
noted that lead fishing gear ingested by common loons is
typically close in size to the pebbles which these birds
ingest to help break down food, suggesting that loons
ingest lost lead tackle from lake substrates (Franson et al.
2001).
Similar to mortality patterns in common loons, mute
swan (Cygnus olor) mortality from ingested lead tackle and
median blood lead levels in England peaked during fishing
season, prior to legislation banning lead fishing weights
(Birkhead 1982,1983; Sears 1988). Sears (1988) suggested
that, in addition to swans ingesting tackle as grit, some
swans likely ingested tackle from fishing lines, possibly
after becoming entangled in line caught in vegetation or
from eating bait attached to tackle. Fourteen percent of
dead swans in the Thames Valley had associated tackle in
their gizzards (Sears 1988). Subsequent to the ban, the
previously documented spike in lead exposure during
fishing season became less evident, suggesting that swans
may be ingesting lead weights as grit that were lost prior to
the ban rather than those recently lost or in current use
(Sears and Hunt 1991; Perrins et al. 2002; Kelly and Kelly
2004).
Lead tackle ingestion in swans
The problem of mortality in wildlife from lead fishing
tackle ingestion was first extensively documented in mute
swans in the United Kingdom (UK). Goode (1981) reported
that lead fishing tackle accounted for 50% of documented
swan mortalities throughout England in 1980–1981, and
estimated that approximately 3000–3500 swans in the UK
died annually as a result of lead poisoning. Researchers
also documented declines in local populations amid high
rates of mortality from lead tackle ingestion (Goode 1981;
Kirby et al. 1994). The majority ([70%) of documented
lead poisoned swans had ingested split shots (Birkhead
1982; Sears 1988; Sears and Hunt 1991) and *7% had
ingested larger weights (Sears and Hunt 1991). Less than
2% of cases of lead poisoning among mute swans in the
UK were attributable to ingested lead shot ammunition
(Sears and Hunt 1991). Lead tackle ingestion impacted
both adult swans and cygnets (Birkhead 1982; Sears 1988;
Kirby et al. 1994; Wood et al. 2019).
After legislation took effect in 1987 in England and
Wales to ban the sale and use of lead fishing weights,
mute swan deaths from lead poisoning declined from 34%
of documented mortalities between 1971 and 1986 to 6%
between 1987 and 2014 (Wood et al. 2019). The mute
swan population rebounded, more than doubling accord-
ing to a population index in the years following the leg-
islation, with a model including the legal status of lead
explaining 82% of the variation in population size (Wood
et al. 2019). Despite this, after an initial decline in median
blood lead levels among non-breeding flocks (Sears and
Hunt 1991), subsequent sampling of swans brought to
rescue centers in England (1994–2002) showed [60% of
birds still had lead levels that exceeded levels considered
elevated for lead ([1.21 lmol/l; Perrins et al. 2002; Kelly
and Kelly 2004). Researchers concluded that lead poi-
soning remains a threat to swans (Perrins et al. 2002;
Newth et al. 2013; Wood et al. 2019), but the regulation
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of lead tackle has resulted in the recovery of the popu-
lation (Wood et al. 2019).
Mortality from lead fishing tackle ingestion has been
documented in other swans, including trumpeter swans
(Cygnus buccinator;Blusetal.1989;Blus1994;
Degernes et al. 2006), tundra swans (Cygnus colum-
bianus; Owen and Cadbury 1975;Blus1994), and
whooper swans (Cygnus cygnus; Spray and Milne 1988;
Perry 1994). However, the majority of documented lead
poisoning in these species has resulted from ingested
lead ammunition (Blus 1994; O’Connell et al. 2008).
Mute swans may be more susceptible to poisoning from
ingested lead fishing tackle and less from ingested lead
ammunition owing to their preference for foraging in
aquatic habitats over agricultural fields in comparison
with other swan species (Ciaranca et al. 1997;Bowen
and Petrie 2007). The susceptibility of mute swans to
lead fishing tackle ingestion can also likely be attributed
to their habitation in urban areas, where they are fed by
humans and may be attracted to anglers’ baits and areas
in which lost lead tackle may accumulate (Sears 1989).
Lead tackle ingestion in common loons
Lead poisoning from ingested fishing tackle in common
loons was first documented in 1976 (Locke et al. 1982) and
has subsequently been documented to be a leading cause of
mortality for this species (Pokras and Chafel 1992; Stone
and Okoniewski 2001; Sidor et al. 2003; Strom et al. 2009;
Grade et al. 2018). Across the range of common loons in
North America, lead poisoning accounts for 11–49% of
documented mortality (Table 2). Differences among
regions should be interpreted with caution and are likely a
function of differing reporting methods, collection efforts,
and sample sizes, as well as real differences in fishing
pressures and loon populations. Mortality from ingested
lead fishing tackle primarily occurs among adult loons on
the summer breeding lakes (Ensor et al. 1992; Daoust et al.
1998; Sidor et al. 2003), although loon deaths from
ingested lead tackle have been documented on wintering
grounds (Sidor et al. 2003; Pokras, unpubl.; Loon Preser-
vation Committee, unpubl.) and among migrating loons in
Washington and on the Great Lakes (Cooley and Melotti,
Table 2 Mortality from lead poisoning in common loons in North America. Unless specified otherwise, ‘‘Total Mortalities Collected’’ include
all age classes
State/country/
region
% Lead
mortalities
Total mortalities
collected
Population size (in most
recent year of study)
Years of
study
Source
New Hampshire
a
48.6 253 (NH AD
population only)
638 1989–2012 Grade et al. (2018)
Maine 25.2 480 (AD only) 4100 (in 2010) 1990–2017 B. MacDonald, pers. com.;
Evers et al. (2010)
New York
b
20 261 1900–2300 1972–2017 Stone and Okoniewski (2001);
J. Okoniewski, pers. com.
New England 44 254 (Breeding AD
only)
1987–2000 Sidor et al. (2003)
Canada 15.0 433 (AD only) *500,000 1992–2018 E.J. Parmley, pers. com.; CLLS
(2019)
Michigan
c
14.1 340 (AD only) 700–800 breeding pairs 1987–2017 J. Melotti, pers. com.
Wisconsin *20 *100 4350 2006–2017 Strom et al. (2009); S. Strom,
pers. com.
Minnesota 11.4 132 12,000 1976–1991, 2009–2015 C. Henderson, pers. com.
Washington 38% from 1996
to 2010; 0%
post-2010
21 (AD only)
1996–2010; 5 AD
post-2010
50 1996–2018 D. Poleschook and V. Gumm,
pers. com.
AD adult
a
Common loon mortality from lead poisoning is underrepresented in New Hampshire because the Grade et al. (2018) study included only loons
that were clearly from the New Hampshire loon population and for which multiple lines of evidence indicated that birds died from lead fishing
tackle ingestion. Thus, cases of lead-poisoned loons were excluded from this study that would have been included in studies and reporting from
other regions
b
Twenty-one additional loons that died from ingested lead fishing tackle were collected during type E botulism outbreaks on the Great Lakes in
New York. Because the total number of dead loons collected during these outbreaks in New York is unknown, these lead mortalities are not
included in the numbers reported in this table
c
Note that ‘‘% Lead mortalities’’ and ‘‘Total mortalities collected’’ in Michigan include loons collected from type E botulism events on the Great
Lakes
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pers. com.; Poleschook, pers. com.). Datasets that combine
wintering and migrating adults generally result in lower
rates of lead tackle ingestion than datasets reporting mor-
tality among the breeding population. Lead poisoning has
not been documented in loon chicks (Sidor et al. 2003),
although it does occur in generally low rates among juve-
nile and sub-adult loons. An exception to this is in
Michigan, where 15 of 60 juvenile/sub-adult loons were
recorded to have died from lead poisoning (numbers not
included in totals reported for Michigan in Table 2, which
includes only adult loons; Cooley and Melotti, unpubl.). In
regions where mortality numbers reported in Table 2
include age classes other than adults, rates of lead tackle
mortality are diluted by younger age groups.
Collection efforts for dead loons are known to vary widely
among different areas in North America (Table 2). In New
Hampshire, the Loon Preservation Committee (LPC) con-
ducts intensive monitoring of the state’s loon population and
has extensive public outreach to encourage reporting of
moribund or dead loons. LPC estimated that its recovery of
deceased loons on breeding grounds is *60%, resulting in
mortality rates that are representative of causes of death
(Grade et al. 2018). Less intensive collection efforts in other
regions depend on a variety of factors, such as available
funding and differing agency priorities and levels of public
outreach, resulting in smaller sample sizes and less repre-
sentative samples of loon mortality. In some states and
regions, mortality sampling may occur in association with
outbreaks of type E botulism in migratory birds. In general,
increased rates of lead fishing tackle mortality are associated
with more intense collection efforts and sample sizes that are
more representative of overall mortality rates (Stone and
Okoniewski 2001; Strom et al. 2009).
Fishing pressure in a given region appears to play a sig-
nificant role in the rate of lead fishing tackle mortality.
Although collection effort can be a confounding factor,
resulting in areas with high fishing pressure but low docu-
mented rates of lead tackle mortality, the role of angling
pressure in rates of lead tackle mortality is evident. Portions
of southern Ontario with high rates of fishing pressure had
the most frequent incidence of lead fishing tackle mortality
among common loons in Canada (Scheuhammer et al. 2003).
Similarly, in New England, New Hampshire’s high rate of
lead tackle mortality compared with the rate in Maine is
likely accounted for by high fishing pressure in the state
(Scheuhammer et al. 2003), although a more intense effort to
collect loon cadavers in New Hampshire likely plays a role.
The correlation between the annual peak in lead tackle
mortality in New Hampshire with months of peak fishing
activity (Grade et al. 2018) likewise suggests the role of
fishing pressure on loon mortality from lead poisoning.
Differences in body size across the range of the common
loon may contribute to regional differences in mortality
rates from lead tackle ingestion as well. Larger loons
inhabiting regions near the coasts (Gray et al. 2014) may be
more likely to ingest larger fish, which, in turn, may be
more likely to break fishing lines and ingest tackle. The
role of body size in lead tackle ingestion may also be
reflected in the skewed sex ratio towards males (Grade
2011), which average [20% larger than females (Gray
et al. 2014). For the datasets represented in Table 2for
which the sex ratio of lead tackle mortalities is known, an
overall average of 66.1% of lead mortalities are males,
28.6% are females, and 5.3% are unknown or unrecorded
sex (total n= 469; range: males = 56.9–77.5%, females =
12.5–36.6%, and unknown sex = 0.0–33.3%).
While many factors influence rates of lead tackle mor-
tality, results reported in Table 2need to be interpreted
with caution due to varying collection efforts, differences
in reporting methods, and different criteria for including
loons in studies (e.g., breeding vs. migrating and/or win-
tering loons) and assigning cause of death as lead poison-
ing (e.g., required presence of lead object vs. other
criteria). Given high collection rates and a focus on adults
of the breeding population, the studies for New Hampshire
(Grade et al. 2018) and New England (Sidor et al. 2003)
likely provide the most accurate assessment of the impact
of mortality from lead fishing tackle ingestion on breeding
loons. In New Hampshire, Grade et al.’s (2018) data
indicate that toxicosis from ingested lead fishing tackle has
had a population-level effect on the state’s common loons,
reducing the population by 43% during the years of the
study (1989–2012), and has inhibited the recovery of loons
in the state. For all regions, the numbers presented in
Table 2likely underestimate the impact of lead poisoning
from fishing tackle ingestion on loon populations.
Tackle types and sizes reported in loons
Jigs and sinkers account for the majority of tackle objects
ingested by loons (Table 3), although loons are also known
to ingest swim baits, internal weights from lures, and other
types of tackle (Grade et al. 2018). Typical sizes of eroded
tackle documented in loons ranged from 0.3 to 30.4 g for
sinkers and 0.3 to 20.9 g for eroded jigs (Stone and Oko-
niewski 2001; Pokras et al. 2009; Grade et al. 2018),
although loons can ingest much larger tackle. An eroded
sinker weighing 78.2 g was reported by Franson et al.
(2003) and several previously unreported eroded, saltwater
jigs each exceeding 100 g were removed from loons
recovered on the coasts of Massachusetts and California
(Fig. 1; Grade et al. 2018; Pokras unpubl.).
The high proportion of ingested jigs recorded from
across the range of the common loon highlights the
importance of including lead-headed jigs in legislation
restricting lead tackle to ensure effective protections for
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loons and other wildlife. Grade et al. (2018) recommend
substituting non-lead alternatives for lead sinkers and jigs
weighing B28.4 g to protect loons and other wildlife.
While erosion rates of many metal objects in avian gizzards
are unknown, studies of erosion of lead shot (Cook and
Trainer 1966; Finley et al. 1976) and lead tackle suggest
that erosion may take place fairly rapidly due to the
grinding action with the pebbles that are virtually always
present in adult loon gizzards (Franson et al. 2001; Pokras,
pers. comm.).
SUBLETHAL EFFECTS OF LEAD IN WILDLIFE
While direct mortality from lead ingestion can be signifi-
cant for wildlife, it is also important to consider the sub-
lethal impacts to individuals and populations. The insidious
effects of sub-acute lead exposure can add to the multiple
stressors already affecting wildlife health, and even low
levels of lead exposure may contribute to mortalities
attributed to other causes (Newth et al. 2016; Ecke et al.
2017). Veterinarians and wildlife professionals are just
beginning to investigate the potential effects of sublethal
lead levels in animals, so some of our most detailed
understanding of the sublethal effects from lead comes
from the human medical literature where low level lead
toxicosis is documented to impair a wide variety of meta-
bolic processes (Wani et al. 2015).
In light of associations between low level lead exposure
and impaired neuropsychological function in humans,
similar cognitive effects of sublethal lead poisoning are
beginning to be studied in wildlife. In herring gulls (Larus
argentatus), effects on locomotion, food begging, feeding,
treadmill learning, thermoregulation, and individual
recognition were observed in chicks dosed with lead
(Burger and Gochfeld 1994). The development of aggres-
sive behaviors has been documented in great tits (Parus
major) and northern mockingbirds (Mimus polyglottos)
exposed to heavy metals (Janssens et al. 2003; McClelland
et al. 2019). Just as lead exposure has been found to affect
the human humoral immune response (Metryka et al.
2018), mallards (Anas platyrhynchos) experimentally
exposed to lead shot were found to have impaired antibody
production following antigen challenge compared to con-
trols (Trust et al. 1990). Immunosuppression secondary to
lead exposure may contribute to lowered disease resistance
in wildlife.
Although subtle effects of sub-lethal lead exposure in
wildlife species have been best documented in controlled
laboratory settings, some studies are beginning to investi-
gate how lead exposure may affect the complex behaviors
of animals in their natural environment. For example, Ecke
et al. (2017) identified lead-induced behavioral effects in a
population of free-ranging golden eagles (Aquila chrysae-
tos). Sublethal lead concentrations were associated with
impaired flight performance and increased mortality risk. A
retrospective study of mute swans admitted to a wildlife
Table 3 Types of fishing tackle removed from loons that died from lead poisoning. Data from the same mortality datasets in Table 2. Pokras
et al. (2009) uses the mortality dataset from Sidor et al. (2003)
State/country/
region
% Jigs % Sinkers % Unknown/
other lead object
Total n of lead
tackle objects
Source
New Hampshire 52.6 38.8 8.6 116 Grade et al. (2018)
New York 68.7 20.9 10.5 67 Stone and Okoniewski (2001);
J. Okoniewski, pers. com.
New England 19.0 60.0 21.0 222 Pokras et al. (2009)
Canada 25.6 39.5 34.9 43 E.J. Parmley, pers. com.
Michigan 53.2 25.5 21.3 47 J. Melotti, pers. com.
Fig. 1 Lateral radiograph of large (116 g) lead jig ingested by
common loon. (Steel shot identified on radiograph and recovered at
necropsy had been present for an extended period and were not
associated with significant pathology.)
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care center for rehabilitation suggested that birds with
elevated but moderate blood lead levels suffered an
increased risk of collision with powerlines or other over-
head cables. Those with intermediate to high levels had a
reduced risk of collision, possibly because they were too
weak to fly (Kelly and Kelly 2005). Karstad (1971), Hunter
and Haigh (1978), and de Francisco et al. (2016) docu-
mented significant effects of lead on the cardiovascular and
nervous systems of birds.
Pattee and Pain (2003) documented an increasing use of
lead worldwide and state that ‘‘lead concentrations in many
living organisms may be approaching thresholds of toxicity
for the adverse effects of lead.’’ Environmental lead
exposure, even at low levels, could very well contribute to
wildlife mortality by impairing organ functions, increasing
susceptibility to trauma and disease, and hindering the
complex mental processes and social behaviors required
for reproductive success and survival.
LEAD IN FISHING GEAR AND HUMAN HEALTH
In regard to consumer lead products and public health, we
are at a critical moment where regulations urgently need to
catch up with the science. In human health, current science
asserts that no safe exposure level exists for lead, which
contributes to 0.6% of the global burden of disease (WHO
2009). Given the growing body of evidence that even low
doses of lead exposure over time can lead to multiple
health and cognitive impairments, one should not under-
estimate the human health hazards associated with han-
dling lead fishing gear.
Sahmel et al. (2015) found that simply handling fishing
sinkers resulted in deposition of lead on the skin and that an
average of 24% of this lead could be transferred from the
hands to the mouth. Practices such as biting lead split-shot
to secure onto the line and melting down scrap lead to
produce home-made fishing weights are both examples of
significant public health concerns directly related to lead
fishing weights. Molds to cast homemade sinkers, jigs,
bullets, lead soldiers, and other items are readily available
for purchase, and there are numerous internet videos
illustrating such techniques without providing any mean-
ingful safety and health information. Indeed, many sources
document significant lead exposure from the melting of
lead at home to make fishing gear and other objects
(Olivero-Verbel et al. 2007; Khan 2014). These cases
expose people to lead via fumes and small particulates that
can be inhaled or may contaminate food and water.
The ingestion hazard to humans posed by small fishing
weights should not be overlooked. Poison control centers are
commonly consulted on cases of ingestion of lead foreign
bodies, and previous studies have noted that some of these
are fishing weights (Cole et al. 2010). In 2016, 2412 of the
poisoning cases reported to poison control centers in the US
were due to single exposures to lead, typically due to the
ingestion of small lead items (Gummin et al. 2017). In many
cases the lead item ingested was not defined. However, in 38
cases reported to US poison control centers in 2016 the item
ingested was specifically recorded as lead fishing tackle and
most of these (28 cases) were due to ingestion by children
under 6 years of age (Gummin et al. 2017). Note that not all
ingestions of lead sinkers will result in reports to poison
control centers and the toxic impacts of the exposure may not
be immediately evident. It is likely that the poison control
center numbers underestimate of the total number of children
exposed to lead via this route. Significantly elevated blood
lead levels have been documented in children exposed to
lead for very short periods of time. For example, blood lead
levels in a 4-year old child were found to exceed 65 lg/dl the
day following ingestion of a single fishing sinker (Cole et al.
2010). Retention of lead fishing sinkers in the stomach and
intestines of children following ingestion has been demon-
strated and can result in long-term elevation of lead levels
(Mowad et al. 1998).
Concerns regarding the public health impacts of lead
exposure have resulted in regulations on other lead prod-
ucts including paint, toys, and gasoline additives (Stroud
2015). The human health perspective should also inform
the risk management strategy for other lead products
including lead fishing gear (Health Canada 2013).
VOLUNTARY AND LEGISLATIVE APPROACHES
FOR REGULATING LEAD FISHING GEAR
Over more than three decades and in multiple jurisdictions,
many approaches have been used to try to reduce the toxic
impacts of lead fishing gear on wildlife. In our ESM
(electronic supplementary materials), we summarize the
effectiveness of key voluntary and legislative measures that
have been used thus far. We assessed the effectiveness of
each measure in terms of reduced uses of lead tackle and/or
reduced mortality wherever data are available (Table S1).
We then used this review to develop recommendations for
the design of a risk management strategy to reduce the
toxic impact of lead fishing gear on wildlife (Table 4).
In reviewing data on effectiveness of risk management
measures, it is important to note that there can be high year
to year variability in the number of mortalities recorded in
any population, and many animals killed by lead tackle
ingestion may not be recovered or subject to post mortem
examination (Pain 1991). Long term monitoring programs
and assessment of trends over many years are essential to
determine the impact of risk management measures. Such
data are not available for all jurisdictions. Several case
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studies are discussed in detail as these examples have the
advantage of long-term monitoring data linked to voluntary
and legislative approaches that evolved over time, allowing
us to learn from their sustained efforts and experience. As
Thomas and Guitart (2003) said, ‘‘…resolving lead expo-
sure and toxicosis of wildlife is more about the develop-
ment of appropriate social and governmental policy than
the state of science.’’ This was reinforced by Arnemo et al.
(2016) who stated, ‘‘Our understanding of the deleterious
impacts of …lead exposure on wildlife and humans will
change little with further scientific research, no more evi-
dence is required….This is now a socio-political issue.’’
Voluntary and education-only approaches to manage
risks from lead fishing gear have proved ineffective,
including efforts in the UK, Sweden, Denmark, and several
US states (LPC 2012; Wood et al. 2019). As a result,
legislative restrictions have been introduced in many
jurisdictions (Table S1). In Washington State, it was noted
that a sizable portion of anglers given on-site education
about the toxicity of lead fishing tackle indicated that they
would change in the future but only when an actual ban
was in place (Poleschook and Gumm 2009). This attitude
has also been noted in other jurisdictions. For example,
following a 15-year outreach effort in Sweden to encourage
the sale and use of non-toxic tackle, retailers stated that
they did not intend to start selling alternatives until legis-
lation banning lead tackle was introduced (KEMI 2007). In
Minnesota, a well-funded 10-year outreach program was
initiated to reduce mortalities from ingested of lead fishing
tackle. This program was described as, ‘‘one of the most
ambitious in the country’’ (LPC 2012). The campaign
included over 200 tackle exchange programs which col-
lected 8000 lbs. of lead, the distribution of 50 000 sample
packages of lead-free tackle, displays at retail stores, and
extensive media coverage. Despite such efforts, this pro-
gram failed. At the end of the program, the supervisor of
the Sustainable Development Unit of the Minnesota Pol-
lution Control Agency concluded, ‘‘I believe no one
Table 4 Recommendations for risk management strategy development for regulating lead fishing tackle. Developed from the review of existing
international voluntary and legislative approaches found in Table S1 for this publication
Conclusions based on international efforts to date Recommended instrument design features
Voluntary/education only approaches ineffective Use a combination of legislation (regulatory restriction on lead sinker/
jig sales and uses) with education to support regulation
Limited product restrictions based on size can be inadequate If a size range is specified in the regulation, ensure that it covers
ingestion hazard for all sizes that are typically ingested by receptors
of concern, or restrict all sizes of lead terminal tackle (note that sizes
specified in most existing legislation are based on heavily impacted
species such as loons but other wildlife species and children can also
ingest these lead products)
Risk management strategies that are very limited in geographical scope
have little, if any, impact on the overall market for lead fishing gear.
If the scope of the restriction excludes large numbers of the angling
community, it will be ineffective in driving change
Restrictions should be applied at the state or national level wherever
possible to ensure the fishing tackle market transitions from lead to
lead-free non-toxic alternatives. Restrictions should apply equally to
all anglers
Stockpiles of existing lead sinkers/jigs continue to be problematic years
following introduction of restrictions
Restriction should be applied to both sale and use and be combined
with effective enforcement. Enforcing a ban on uses also prevents the
continued manufacture and use of home-made lead fishing weights
and prevents purchasing from other jurisdictions that do not have
restrictions on sales. Use education and enforcement, combined with
buy-back programs, to ensure anglers cease use of lead in existing
supplies. In some jurisdictions effective enforcement at the point of
use may require cooperation between different levels of government
Lack of availability of non-lead alternatives for purchase by anglers and
higher cost of alternatives can be a deterrent for switching to non-
lead
Restrictions on sale ensure a guaranteed market for non-lead
alternatives, hence manufacturers will produce them and retailers
will stock them. Costs of non-lead alternatives expected to fall in any
market with effective regulatory restrictions on lead due to increased
economy of scale for non-lead options
Exclusions for coated lead products in some restrictions not supported
by science, as coating is readily eroded after ingestion and is
ineffective in limiting exposure or toxicity
Restrictions should not include exclusions for coated products
Wildlife are exposed to lead from multiple sources, toxicosis and
mortalities occur from many
Coordinated action on a variety of lead products may be required for a
comprehensive and effective risk management strategy
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knowledgeable about our concerted and sustained educa-
tional efforts in Minnesota would make the claim that
education alone will sufficiently reduce or eliminate
avoidable loon deaths as a result of lead ingestion’’ (LPC
2012).
This review of voluntary and legislative approaches
concurs with the conclusion that, ‘‘a comprehensive solu-
tion involving legislation backed by intensive educational
efforts will be required to address this issue’’ (LPC 2012).
It is also clear that legislation developed must be appro-
priately designed to effectively address the issue (see
Table 4). For example, legislation that fails to ban all sizes
and types of lead tackle documented to be regularly
ingested by wildlife will fail to adequately address the
issue. Legislation that bans sale but not use will be much
less effective since existing stocks of lead tackle will
continue to be used, may continue to be purchased from
jurisdictions outside the ban, and may continue to be cast at
home (also resulting in public health concerns regarding
lead exposure). Conversely legislation that bans use but not
sale would leave lead tackle readily available, make
enforcement difficult and discourage anglers from adopting
nontoxic alternatives. Legislation that is limited in geo-
graphical scope and does not include both sale and use bans
will have little, if any, impact on overall market demand
for lead fishing gear. Enforcement throughout supply-
chains is also critical. Even in Denmark, a jurisdiction with
complete bans on importation and sale of all sizes of lead
fishing tackle since 2002, lead fishing gear was found on
sale in 2012 and 2013 (Danish EPA 2014). In this case,
active enforcement and fines applied in recent years appear
to be gradually reducing violations.
Ideally one might wish to advocate for elimination of all
fishing tackle containing lead. But given historical oppo-
sition to attempts to limit lead sinkers and jigs by some
fishing groups, tackle retailers, and tackle manufacturers,
regulators have been reticent to extend bans beyond the
sizes and types of ingested tackle documented to harm
wildlife. Elected officials find themselves trying to recon-
cile the sometimes conflicting goals represented by the
scientific data and jurisdictional economic priorities and
political realities. Therefore, it is important to document
sizes and types of ingested tackle and to press for science-
based restrictions to protect wildlife.
The most effective risk management instrument is
expected to be one that includes a prohibition on
importation, manufacturing (including home casting),
sale, and use of fishing tackle items made from lead.
This needs to be combined with educational outreach to
support the legislation and effective enforcement
throughout the supply chain (at domestic manufacturing
facilities, at importation, at points of sale, and at points
of use).
DISCUSSION: SEEKING SOLUTIONS THROUGH
EDUCATION AND POLICY CHANGE
The role of human dimensions: Social science
research and communication
Management decisions regarding lead fishing tackle have
the potential to be very controversial, and legislation
designed to protect wildlife is often met with resistance
(Kneeland and Pokras 2008). Stakeholders are diverse, as
this issue concerns government agencies, conservation
non-profits, anglers, wildlife-viewers, fishing tackle retail-
ers, manufacturers, and others. Stakeholder involvement in
decision-making processes has increased the demand for
human dimensions research in order to understand and
predict stakeholder positions (Vaske and Manfredo 2012).
Also, since human behavior is the root cause of lead in
freshwater environments from fishing tackle, understanding
angler behaviors is essential for accomplishing conserva-
tion goals (Ross-Winslow and Teel 2011), such as
increased legislative awareness and elimination of lead
tackle use.
Human dimensions research applies social psychology
to understand stakeholder thoughts and actions towards
wildlife (Vaske and Manfredo 2012). With this under-
standing, agencies can create more targeted outreach ini-
tiatives and increase message effectiveness, improve
conservation strategies, as well as managing conflicts
among stakeholders (Redpath et al. 2015). Leszek (2015)
found that anglers not using lead-free fishing tackle believe
it is too expensive and were unsure if it would perform as
well as lead. In this case, it may be more effective to frame
communication messages that minimize perceived barriers
(Ross-Winslow and Teel 2011), rather than focus solely on
traditional educational efforts involving lead toxicity or
wildlife conservation.
Other approaches measure connections between atti-
tudes and broad value scales, such as altruistic (i.e., caring
about others), egoistic (maximizing individual outcomes),
and biospheric (caring for non-human nature and the bio-
sphere itself) (Stern et al. 1999; DeGroot and Steg 2007).
Altruistic and biospheric values tend to be positively
related to environmental policy acceptability, while ego-
istic values appear to be negatively related (Stern et al.
1999). Changes to values are unlikely to occur after edu-
cation and informational campaigns because values are
central to one’s identity and are relatively stable over the
course of a lifetime (Fulton et al. 1996). Therefore, rather
than attempting to change environmental values, another
strategy is to promote messages that match those values. In
the case of lead fishing tackle, it may be beneficial to focus
on messages that appeal to egoistic values in addition to
biospheric. Implementing message campaigns that focus on
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the human health hazards of lead, for example, might
appeal to those expressing fewer concerns about wildlife
health but are more concerned about their own personal
well-being.
Many anglers may simply be unaware that lead fishing
tackle causes ecological harm (Kneeland and Pokras 2008),
but cognitive-based outreach approaches (i.e., presenting
scientific information to the public) may not always be
effective. Human behaviors are also influenced by beliefs,
attitudes, value orientations, emotions, social norms,
experience, and many other complex factors (Vaske and
Manfredo 2012). An understanding of these factors is
essential for designing effective communication messages.
Since behaviors and attitudes of stakeholders regarding
lead fishing tackle are still largely unknown (Thomas 1997;
Ross-Winslow and Teel 2011), the authors recommend
future studies to explore these relationships.
The taxonomy of fishing gear
In crafting educational and regulatory efforts on lead
fishing gear, one of the problematic issues has been that
manufacturers, marketers and anglers use a wide variety of
terms for different fishing weights. Lead can be cast in
many forms for fishing including items such as split shot,
worm weights, trolling weights, jigs, ad infinitum. Initial
attempts to regulate lead fishing gear focused on ‘‘sinkers,’’
but the term ‘‘sinker’’ only applies to certain types of
fishing weights. In the U.S., many fishing groups were able
to avoid proposed regulations by claiming that other types
of fishing weights are not ‘‘sinkers.’’ The gear identified as
‘‘jigs’’ or ‘‘jigheads’’ in the U.S. is referred to as ‘‘lures’’ in
the UK. Thus, in developing regulatory and educational
materials, we should either make exhaustive lists of types
of fishing gear that contain lead or consider a more inclu-
sive terminology; perhaps something like, ‘‘any tackle,
weights or lures containing lead used for fishing’’.
The authors also note that there is potential for mis-
classification of lead objects retrieved from avian GI tracts.
Larger or more intact objects like bullets, jigs and sinkers
are unlikely to be confused. But there is significant
opportunity for inaccurate classification of smaller
deformed or eroded objects, and it can sometimes be hard
or impossible to tell if original objects were of fishing or
shooting origin. Some of us have spent significant time
using dissecting microscopes, magnets and other tools in
attempts to differentiate eroded split shot or small jigs from
gunshot, bullet fragments, or lead fragments from non-
sporting origins. Over time we have improved our skills,
but there are still items that end up being classified as
‘‘unknown Pb.’’ Because of the challenges associated with
the identification of some deformed lead objects, we sus-
pect that some things identified in other studies as being
firearm projectiles may in fact have been fishing gear.
Coatings for lead fishing gear
Some groups have claimed that coating fishing gear with
paint or other materials would prevent lead from being
absorbed after ingestion. USFWS (1986) detailed extensive
testing (some going back to the 1940s and 1950s) that had
been done to see if lead shot could be coated to make them
non-toxic when ingested by waterfowl. Those experiments
concluded that for most practical purposes, coatings were
uniformly unsuccessful and were quickly ground off in
waterfowl gizzards. Thomas et al. (2015) reinforce the
ineffectiveness of coatings for gunshot. To model what
takes place with coated fishing gear ingested by common
loons, Pokras (unpubl.) is currently testing commercially
available painted or coated fishing weights in rock tumblers
containing simulated gastric acid and the types of pebbles
usually found in loon gizzards (Franson et al. 2001). Work
to date has found that within 24 h, even heavily applied,
multi-layer paint coatings are eroded enough to expose the
metallic lead to gastric fluids. Thus, any legislation
excluding coated or painted fishing tackle will be ineffec-
tive in preventing mortalities from lead poisoning.
Alternative materials
It may be that only metals have suitable characteristics for
the temperatures and pressures encountered inside firearms.
Thomas (2019) reviews the advantages and disadvantages
of a variety of metals for ammunition and angling. For
fishing, a variety of non-metallic materials can be suit-
able substitutes including natural rock and porcelain
products.
An internet search for topics such as ‘‘rock fishing
sinkers,’’ ‘‘biodegradable sinkers,’’ or ‘‘non-metal fishing
weights’’ shows numerous alternative products. Most pri-
ces are similar to those of lead products. Sinkers and jigs
made of non-toxic metals are also on the market, including
tackle made of tungsten, tin, bismuth, and steel. Tungsten’s
high density makes it a preferred material among profes-
sional anglers. However, fishing weights containing other
toxic metals including zinc and cadmium have been found
in U.S. stores, often bearing labels such as, ‘‘This Product
Does Not Contain Lead.’’ Regulators and educators must
be aware of this practice and take steps to avoid having
these or other toxic substitutes enter the marketplace.
Appendix S1 for this paper contains information on some
sources for non-toxic fishing gear.
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Other fishing-related issues
Clearly fishing activities deposit large amounts of metallic
lead and other materials into a variety of aquatic environ-
ments (Bell et al. 1985; Forbes 1986). In addition to
ingestion of such fishing gear by non-target species, under
some conditions a great deal of lead can enter sediments
and the water. Jacks et al. (2001) discuss the erosion of lead
fishing gear in a Swedish river. Binkowski (2017) discusses
environmental conditions, especially low pH, under which
lead from spent gunshot or fishing gear may be transferred
to sediments and the water column. The effects of this lead
on aquatic organisms is deserving of further study but
should be similar to lead deposited into aquatic systems
from mining activities, shooting, industrial effluent, or
other sources.
Effects of lead on individual animals
Traditionally wildlife managers have primarily been con-
cerned about threats to animal health in two circumstances.
First, if such threats are shown to have population-level
effects on the species in question, and second, if these
threats may serve a sentinel function to protect human
health. There is no doubt that both of these are good rea-
sons to replace lead in fishing gear with non-toxic
alternatives.
But the authors would be remiss if we did not point out
the significant benefits to individual animals of switching
to non-toxic fishing gear. Hunters and anglers have long
been some of our most ardent conservationists and tra-
ditionally abhor the unnecessary killing of non-target
animals (Reiger 1975). Even if lead poisoning is not
having a population-level effect on a particular species, it
is killing large numbers of animals in a manner that is
often prolonged, painful, and cruel. This flies in the face
of two of the historic central tenets of sporting traditions:
first, that we should avoid harm to non-target species, and
second, that wild animals being taken for food or sport
should, whenever possible, be afforded a quick death.
Lead poisoning is inhumane and causes unnecessary
stress, pain, and suffering in a wide variety of species
including people, dogs, horses, ruminants, and birds.
There is abundant literature over many years to demon-
strate acute abdominal pain, peripheral muscle pain and
weakness, incoordination, seizures, anemia and weakness,
gout, and other clinical problems seen in many taxa
(Oliver 1914;Walker1981;Nriagu1983; Needleman
2000;Blakley2019). It is worth considerable money and
effort to eliminate this poison from our outdoors
activities.
CONCLUSIONS
There is a significant need to improve the development,
marketing, adoption and regulatory approaches for non-toxic
fishing gear. Those of us interested in reducing the use of
lead need to develop strategies to increase the acceptance of
non-toxic alternatives and educate anglers about:
1. The dangers of lead fishing gear to human and animal
health
2. The availability and costs of non-toxic alternatives
3. The fact that non-lead fishing gear is suitable for their
angling goals. This may include funds for demonstra-
tion activities such as lead fishing gear exchange
programs, lead-free fishing derbies, and other
programs
4. Dramatically improve the marketing of non-lead
fishing gear.
Part of the solution may be developing novel business
models. One suggestion, based on the regulatory desire to
reduce the health threat from tobacco use, would be
introduce a significant ‘‘sin tax’’ on the manufacture or sale
of lead (or other toxic) fishing gear. Funds generated from
such taxes could be dedicated to such things as research on
non-toxic alternatives, public education, and other goals.
Compiling information for this paper has also made it
clear that further efforts should be made to improve our
knowledge and data collection about the ingestion of lead
fishing gear. To paraphrase Sainsbury et al. (2001), with
few exceptions, current programs to investigate morbidity
and mortality of wildlife are fragmented and uncoordi-
nated, often being limited to specific narrow taxonomic
foci, large-scale outbreaks, or focal geographic areas. Due
to limited time, personnel and funding, data collected in
one jurisdiction are often not easily comparable with those
collected elsewhere. Enhancements in citizen science
efforts (including some STEAM education programs—
Science, Technology, Engineering, the Arts, and Math)
may provide opportunities to correct some of these defi-
ciencies in the future.
We recommend that the following points can be
important when developing scientific, educational and
regulatory efforts for managing the risks associated with
lead fishing gear:
1. It is important to specify what alternative materials are
safe and non-toxic based on best available science and
not simply to say ‘‘non-lead’’
2. Scientists and agencies should work collaboratively
with anglers’ groups, retailers, manufacturers and
regulators to accelerate the development, marketing
and acceptance of nontoxic fishing tackle
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3. Anglers, manufacturers, sellers and regulators should
be helped to understand that coatings will not render
lead fishing gear safe and non-toxic
4. To enhance long-term data compatibility and sharing,
researchers and agencies should consider more widely
circulating their study plans, priorities and protocols.
This will have the effect of more rapidly advancing
science and accelerating the development of sound,
science-based policies.
5. Voluntary and educational approaches alone are not
effective for risk management and must be combined
with legislative approaches which incorporate the
features summarized in Table 4of this paper.
Acknowledgements We would like to thank the following people for
contributing their data and perspectives to the development of this
paper: Eric Corneau, Environment and Climate Change Canada,
Gatineau, Que., Canada. Susan Gallo, Maine Audubon Society, Fal-
mouth, ME, USA. Meghan Hartwick, Univ. of New Hampshire,
Durham, NH USA. Carrol Henderson, Minnesota Dept. of Natural
Resources, St. Paul, MN, USA. Erica LeMoine, Sigurd Olson Inst.,
Northland College, Ashland, WI, USA. Daniel and Ginger Pole-
schook, loon biologists, Loon Lake, WA, USA. Sean Strom, Wis-
consin Department of Natural Resources, Madison, WI, USA. Jillian
Whitney, Massachusetts Department of Conservation and Recreation,
West Boylston, MA, USA.
REFERENCES
Anderson, W.L., S.P. Havera, and B.W. Zercher. 2000. Ingestion of
lead and nontoxic shotgun pellets by ducks in the Mississippi
Flyway. Journal of Wildlife Management 64: 848–857.
Arnemo, J.M., O. Andersen, S. Stokke, V.G. Thomas, O. Krone, D.J.
Pain, and R. Mateo. 2016. Health and environmental risks from
lead-based ammunition: Science versus socio-politics. Eco-
Health 13: 618–622.
Bell, D.V., N. Odin, and E. Torres. 1985. Accumulation of angling
litter at game and coarse fisheries in South Wales, UK.
Biological Conservation 34: 369–379.
Bengfort, J., and R.W. Carithers. 1976. Lead poisoning in dogs. Iowa
State University Veterinarian, 38. https://lib.dr.iastate.edu/
iowastate_veterinarian/vol38/iss3/4.
Binkowski, L.J. 2017. The influence of environmental conditions on
lead transfer from spent gunshot to sediments and water: Other
routes for Pb poisoning. Chemosphere 187: 330–337.
Birkhead, M. 1982. Causes of mortality in the mute swan, Cygnus
olor, on the River Thames. Journal of Zoology 198: 15–25.
Birkhead, M. 1983. Lead levels in the blood of mute swans, Cygnus
olor, on the River Thames. Journal of Zoology 199: 59–73.
Blakley, B.R. 2019. Overview of lead poisoning. Merck Veterinary
Manual (online). https://www.merckvetmanual.com/toxicology/
lead-poisoning/overview-of-lead-poisoning
Blus, L.J. 1994. A review of lead poisoning in swans. Comparative
Biochemistry and Physiology Part C 108: 259–267.
Blus, L.J., R.K. Stroud, B. Reiswig, and T. McEneaney. 1989. Lead
poisoning and other mortality factors in trumpeter swans.
Environmental Toxicology and Chemistry 8: 263–271.
Borkowski, R. 1997. Lead poisoning and intestinal perforations in a
snapping turtle (Chelydra serpentina) due to fishing gear
ingestion. Journal of Zoo and Wildlife Medicine 28: 109–113.
Bowen, J.E., and S.A. Petrie. 2007. Incidence of artifact ingestion in
mute swans and tundra swans on the Lower Great Lakes,
Canada. Ardea 95: 135–142.
Brown, M.J., E. Linton, and E.C. Rees. 1992. Causes of mortality
among wild swans in Britain. Wildfowl 43: 70–79.
Burger, J., and M. Gochfeld. 1994. Behavioral impairments of lead-
injected young herring gulls in nature. Fundamental and Applied
Toxicology 23: 553–561.
Ciaranca, M.A., C.C. Allin, and G.S. Jones. 1997. Mute swan (Cygnus
olor), version 2.0. In The Birds of North America, eds. A.F.
Poole and F.B. Gill. Ithaca, NY: Cornell Lab of Ornithology.
https://doi.org/10.2173/bna.273.
CLLS (Canadian Lakes Loon Survey). 2019. The Canadian lakes
loon survey: Science for lake and loon conservation.https://
www.birdscanada.org/volunteer/clls/resources/CLLSBrochure.
pdf.
Cole, J.B., S.J. Stellpflug, A. Karpas, and D.J. Roberts. 2010.
Ingestion of one lead fishing sinker resulting in toxic lead levels
within hours [abstract]. Clinical Toxicology 48: 622.
Cook, R.S., and D.O. Trainer. 1966. Experimental lead poisoning of
Canada geese. Journal of Wildlife Management 30: 1–8.
Cryer, M., J.J. Corbett, and M.D. Winterbotham. 1987. The deposi-
tion of hazardous litter by anglers at coastal and inland fisheries
in South Wales. Journal of Environmental Management 25:
125–135.
Danish EPA (Environmental Protection Agency). 2014. Report on
lead fishing gear sales in Denmark. Copenhagen, DK: Ministry
of Environment and Food of Denmark. https://mst.dk/service/
nyheder/nyhedsarkiv/2014/maj/miljoestyrelsen-paa-jagt-efter-bly-
i-fiskegrej/
Daoust, P.-Y., G. Conboy, S. McBurney, and N. Burgess. 1998.
Interactive mortality factors in common loons from Maritime
Canada. Journal of Wildlife Diseases 34: 524–531.
de Francisco, O.N., D. Feeney, A.G. Armie
´n, A. Wuenschmann, and
P.T. Redig. 2016. Correlation of brain magnetic resonance
imaging of spontaneously lead poisoned bald eagles (Haliaeetus
leucocephalus) with histological lesions: A pilot study. Research
in Veterinary Science 105: 236–242.
Degernes, L.A., S. Heilman, M. Trogdon, M. Jordan, M. Davison, D.
Kraege, M. Correa, and P. Cowen. 2006. Epidemiologic
investigation of lead poisoning in trumpeter and tundra swans
in Washington state, USA, 2000–2002. Journal of Wildlife
Diseases 42: 345–358.
DeGroot, J., and L. Steg. 2007. Value orientations and environmental
beliefs in five countries: Validity of an instrument to measure
egoistic, altruistic, and biospheric value orientations. Journal of
Cross-Cultural Psychology 38: 318–332.
Duerr, A.E. 1999. Abundance of lost and discarded fishing tackle and
implications for waterbird populations in the United States. MS
Thesis. Tucson, AZ: Univ. of Arizona. http://hdl.handle.net/
10150/278698.
Ensor, K.L., D.D. Helwig, and L.C. Wemmer. 1992. Mercury and
lead in Minnesota common loons (Gavia immer). St. Paul, MN:
Minnesota Pollution Control Agency.
ECCC. 2018. Study to gather use pattern information on lead sinkers
and jigs and their non-lead alternatives in Canada. Gatineau,
QC: Prepared by ToxEcology Environmental Consulting Ltd. for
Environment and Climate Change Canada (ECCC). https://www.
canada.ca/en/environment-climate-change/services/management-
toxic-substances/list-canadian-environmental-protection-act/lead/
using-more-lead-free-fishing-tackle.html.
ECHA. 2018. A review of the available information on lead in shot
used in terrestrial environments, in ammunition and in fishing
123 Royal Swedish Academy of Sciences 2019
www.kva.se/en
Ambio

tackle. Helsinki, Finland: European Chemicals Agency, Annex
XV Investigation report. https://echa.europa.eu/documents/10162/
13641/lead_ammunition_investigation_report_en.pdf/efdc0ae4-
c7be-ee71-48a3-bb8abe20374a.
Ecke, F., N.J. Singh, J.M. Arnemo, A. Bignert, B. Helander, A.M.M.
Berglund, H. Borg, C. Bro
¨jer, et al. 2017. Sublethal lead
exposure alters movement behavior in free-ranging golden
eagles. Environmental Science and Technology 51: 5729–5736.
European Commission. 2004. Advantages and drawbacks of restrict-
ing the marketing and use of lead in ammunition, fishing sinkers
and candle wicks. European Commission Enterprise Directorate-
General COWI CONTRACT NUMBER – ETD/FIF.20030756
Final Report.
Evers, D.C., J.D. Paruk, J.W. McIntyre, and J.F. Barr. 2010. Common
loon (Gavia immer). No. 313. The Birds of North America
Online, ed. A Poole. Ithaca, NY: Cornell Laboratory of
Ornithology. http://bna.birds.cornell.edu/bna/species/313.
Finley, M.T., M.P. Dieter, and L.N. Locke. 1976. Lead in tissues of
mallard ducks dosed with two types of lead shot. Bulletin of
Environmental Contamination and Toxicology 16: 261–269.
Forbes, I.J. 1986. The quantity of lead shot, nylon fishing line and
other litter discarded at a coarse fishing lake. Biological
Conservation 38: 21–34.
Franson, J.C., and D.J. Cliplef. 1992. Causes of mortality in common
loons. In Proceedings from the 1992 conference on the loon and
its ecosystem: Status, management, and environmental concerns,
ed. L. Morse, S. Stockwell, and M. Pokras, 2–12. Concord, NH:
U.S. Fish and Wildlife Service.
Franson, J.C., S.P. Hansen, M.A. Pokras, and R. Miconi. 2001. Size
characteristics of stones ingested by common loons. Condor 103:
189–191.
Franson, J.C., S.P. Hansen, T.E. Creekmore, C.J. Brand, D.C. Evers,
A.E. Duerr, and S. DeStefano. 2003. Lead fishing weights and
other fishing tackle in selected waterbirds. Waterbirds 26:
345–352.
Fulton, D.C., M.J. Mangredo, and J. Lipscomb. 1996. Wildlife value
orientations: A conceptual and measurement approach. Human
Dimensions of Wildlife 1: 24–47.
Galili, E., A. Zemer, and B. Rosen. 2013. Ancient fishing gear and
associated artifacts from underwater explorations in Israel—A
comparative study. Archaeofauna 22: 145–166.
Goode, D.A. (ed). 1981. Lead poisoning in swans. Report of the
Nature Conservancy Council’s Working Group.
Grade, T.J. 2011. Effects of lead fishing tackle on common loons
(Gavia immer) in New Hampshire, 1989–2010. MS Thesis.
Madison, WI: Univ. of Wisconsin.
Grade, T.J., M.A. Pokras, E.M. LaFlamme, and H.S. Vogel. 2018.
Population-level effects of lead fishing tackle on common loons.
Journal of Wildlife Management 82: 155–164.
Gray, C.E., J.D. Paruk, C.R. DeSorbo, L.J. Savoy, D.E. Yates, M.D.
Chickering, R.B. Gray, K.M. Taylor, et al. 2014. Body mass in
common loons (Gavia immer) strongly associated with migration
distance. Waterbirds 37 (sp1): 64–75.
Gummin, D.D., J.B. Mowry, D.A. Spyker, D.E. Brooks, M.O. Fraser,
and W. Banner. 2017. 2016 Annual report of the American
Association of Poison Control Centers’ national poison data
system (NPDS): 34th annual report. Clinical Toxicology 55:
1072–1254. https://doi.org/10.1080/15563650.2017.1388087.
Haig, S.M., J. D’Elia, C. Eagles-Smith, J.M. Fair, J. Gervais, G.
Herring, J.W. Rivers, and J.H. Schulz. 2014. The persistent
problem of lead poisoning in birds from ammunition and fishing
tackle. The Condor 116: 408–428.
Harrigan, K. 1991. Causes of mortality of little penguins, Eudyptula
minor, in Victoria. Emu-Austral Ornithology 91: 273–277.
Health Canada. 2013. Risk management strategy for lead. Ottawa,
ON. https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/
ewhsemt/alt_formats/pdf/pubs/contaminants/prms_lead-psgr_plomb/
prms_lead-psgr_plomb-eng.pdf.
Hunter, B., and J.C. Haigh. 1978. Demyelinating peripheral neuropa-
thy in a guinea hen associated with subacute lead intoxication.
Avian Diseases 22: 344–349.
Jacks, G., M. Bystron, and L. Johansson. 2001. Lead emissions from
lost fishing sinkers. Boreal Environment Research 6: 231–236.
Janssens, E., T. Dauwe, E. Van Duyse, J. Beernaert, R. Pinxten, and
M. Eens. 2003. Effects of heavy metal exposure on aggressive
behavior in a small territorial songbird. Archives of Environ-
mental Contamination and Toxicology 45: 0121–0127.
Karstad, L. 1971. Angiopathy and cardiopathy in wild waterfowl from
ingestion of lead shot. Connecticut Medicine 35: 355–360.
Kelly, A., and S. Kelly. 2004. Fishing tackle injury and blood lead
levels in mute swans. Waterbirds 27: 60–68.
Kelly, A., and S. Kelly. 2005. Are mute swans with elevated blood
lead levels more likely to collide with overhead power lines?
Waterbirds 28: 331–334.
KEMI. 2007. Lead in articles. Stockholm, SE: Reported by the
Swedish Chemicals Agency and the Swedish Environmental
Protection Agency, Report 5/07. https://www.kemi.se/global/
rapporter/2007/rapport-5-07-lead-in-articles.pdf.
Khan, H. 2014. Exposure of lead amongst primary school children in
fishing communities in South Africa. MS Thesis. Univ. of
Witwatersrand, Johannesburg, South Africa. http://146.141.
12.21/bitstream/handle/10539/15464/MMed587333FINAL.pdf?
sequence=1&isAllowed=y.
Kirby, J., S. Delany, and J. Quinn. 1994. Mute swans in Great Britain:
A review, current status, and long-term trends. Hydrobiologia
279: 467–482.
Kneeland, M., and M. Pokras. 2008. Lead poisoning: Using transdis-
ciplinary approaches to solve an ancient problem. EcoHealth 5:
379–385.
Leszek, M. 2015. Changing angler behavior to reduce the impacts of
lead fishing tackle in New Hampshire: Applied social science
using community based social marketing. MS Thesis. Plymouth
State University, Plymouth, NH.
Lloret, J., A. Garrote, N. Balasch, and T. Font. 2014. Estimating
recreational fishing tackle loss in Mediterranean coastal areas:
Potential impacts on wildlife. Aquatic Ecosystem Health &
Management 17: 179–185.
Locke, L.N., S.M. Kerr, and D. Zoromski. 1982. Lead poisoning in
common loons (Gavia immer). Avian Diseases 26: 392–396.
LPC (Loon Preservation Committee). 2012. The efficacy of education
to address loon mortality from ingested lead fishing tackle.
Moultonborough, NH: Loon Preservation Committee.
MacDonald, J.W., R. Goater, N.K. Atkinson, and J. Small. 1990.
Further causes of death in Scottish swans, Cygnus olor.State
Veterinary Journal 44: 81–93.
McClelland, S.C., R.D. Ribeiro, H.W. Mielke, M.E. Finkelstein, C.R.
Gonzales, J.A. Jones, J. Komdeur, E. Derryberry, et al. 2019.
Sub-lethal exposure to lead is associated with heightened
aggression in an urban songbird. Science of the Total Environ-
ment 654: 593–603.
Metryka, E., K. Chibowska, I. Gutowska, A. Falkowska, P. Kupnicka,
K. Barczak, and I. Baranowska-Bosiacka. 2018. Lead (Pb)
exposure enhances expression of factors associated with inflam-
mation. International Journal of Molecular Sciences 19: 1813.
https://doi.org/10.3390/ijms19061813.
MCPA (Minnesota Pollution Control Agency). 2013. Toxics and
pollution prevention evaluation report. St. Paul, MN. https://
www.pca.state.mn.us/sites/default/files/lrp-p2s-2sy13.pdf.
Mowad, E., I. Haddad, and D.J. Gemmel. 1998. Management of lead
poisoning from ingested fishing sinkers. Archives of Pediatric
and Adolescent Medicine 152: 485–488.
Royal Swedish Academy of Sciences 2019
www.kva.se/en 123
Ambio

Needleman, H.L. 2000. Human lead exposure. Boca Raton, FL: CRC
Press.
Newth, J.L., R.L. Cromie, M.J. Brown, R.J. Delahay, A.A. Meharg,
C. Deacon, G.J. Norton, M.F. O’Brien, et al. 2013. Poisoning
from lead gunshot: Still a threat to wild waterbirds in Britain.
European Journal of Wildlife Research 59: 195–204.
Newth, J.L., E.C. Rees, R.L. Cromie, R.A. McDonald, S. Bearhop,
D.J. Pain, G.J. Norton, C. Deacon, et al. 2016. Widespread
exposure to lead affects the body condition of free-living
whooper swans Cygnus cygnus wintering in Britain. Environ-
mental Pollution 209: 60–67. https://doi.org/10.1016/j.envpol.
2015.11.007.
Nriagu, J.O. 1983. Lead & lead poisoning in antiquity. New York:
Wiley.
O’Connell, M.M., E.C. Rees, O
´. Einarsson, C.J. Spray, S. Thor-
stensen, and J. O’Halloran. 2008. Blood lead levels in wintering
and moulting Icelandic whooper swans over two decades.
Journal of Zoology 276: 21–27.
Oliver, T. 1914. Lead poisoning: From the industrial, medical, and
social points of view. New York: Paul B. Hoeber.
Olivero-Verbel, J., D. Duarte, M. Echenique, J. Guette, B. Johnson-
Restrepo, and P.J. Parsons. 2007. Blood lead levels in children
aged 5–9 years living in Cartagena, Colombia. Science of the
Total Environment 372: 707–716.
Owen, M., and C.J. Cadbury. 1975. The ecology and mortality of
swans at the Ouse Washes, England. Wildfowl 26: 31–42.
Pain, D.J. 1991. Why are lead-poisoned waterfowl rarely seen?: The
disappearance of waterfowl carcasses in the Camargue, France.
Wildfowl 42: 118–122.
Pattee, O.H., and D.J. Pain. 2003. Lead in the environment. In
Handbook of ecotoxicology, 2nd ed, ed. D.J. Hoffman, B.A.
Rattner, G.A. Burton Jr., and J. Cairns Jr. New York: Lewis
Publishers.
Pennycott, T.W. 1999. Causes of mortality in mute swans Cygnus
olor in Scotland 1995–1996. Wildfowl 50: 11–20.
Perrins, C.M., P. Martin, and B. Broughton. 2002. The impact of lost
and discarded fishing line and tackle on mute swans. Bristol,
UK: Environment Agency R&D Technical Report W1-051/TR.
Perry, C. 1994. Lead sinker ingestion in avian species. U.S. Fish and
Wildlife Service, Division of Environmental Contamination
Information Bulletin. 94-09-01, Arlington, VA.
Pokras, M.A., and R. Chafel. 1992. Lead toxicosis from ingested
fishing sinkers in adult common loons (Gavia immer) in New
England. Journal of Zoo and Wildlife Medicine 23: 92–97.
Pokras, M.A., M. Kneeland, A. Ludi, E. Golden, A. Major, R. Miconi,
and R.H. Poppenga. 2009. Lead objects ingested by common
loons in New England. Northeastern Naturalist 16: 177–182.
Poleschook, D., and G. Gumm. 2009. Recommendation to ban the use
of lead fishing tackle in Washington. Olympia, WA: Report to
Washington Fish and Wildlife Commission.
Radomski, P., T. Heinrich, T.S. Jones, P. Rivers, and P. Talmage.
2006. Estimates of tackle loss for five Minnesota walleye
fisheries. North American Journal of Fisheries Management 26:
206–212.
Redpath, A.M., R.J. Gutierrez, K.A. Wood, and J.C. Young. 2015.
Conflicts in conservation: Navigating towards solutions. Cam-
bridge, UK: Cambridge University Press.
Reiger, J.F. 1975. American sportsmen and the origins of conserva-
tion. New York: Winchester Press.
Ross-Winslow, D.J., and T.L. Teel. 2011. The quest to eliminate lead
from units of the National Park System: Understanding and
reaching out to audiences. The George Wright Forum 28: 34–77.
Sainsbury, A.W., J.L. Kirkwood, P.M. Bennett, and A.A. Cunning-
ham. 2001. Status of wildlife health monitoring in the United
Kingdom. Veterinary Record 148: 558–563.
Sahmel, J., E.I. Hsu, H.J. Avens, E. Beckett, and K.D. Devlin. 2015.
Estimation of hand-to-mouth transfer efficiency of lead. Annals
of Work Exposures and Health 59: 210–220.
St. Clair, W.S., and J. Benjamin. 2008. Lead intoxication from
ingestion of fishing sinkers: A case study and review of the
literature. Clinical Pediatrics 47: 66–70.
Scheuhammer, A.M. 2009. Historical perspective on the hazards of
environmental lead from ammunition and fishing weights in
Canada. In Ingestion of lead from spent ammunition: Implica-
tions for wildlife and humans, eds. R.T. Watson, M. Fuller, M.
Pokras, and W.G. Hunt. Boise, ID: The Peregrine Fund. https://
doi.org/10.4080/ilsa.2009.0105.
Scheuhammer, A.M., S.L. Money, D.A. Kirk, and G. Donaldson.
2003. Lead fishing sinkers and jigs in Canada: Review of their
use patterns and toxic impacts on wildlife. Ottawa, ON:
Canadian Wildlife Service. Occasional Paper #108.
Scheuhammer, A.M., and S.L. Norris. 1995. A review of the
environmental impacts of lead shotshell ammunition and lead
fishing weights in Canada. Ottawa, ON: Canadian Wildlife
Service Occ. Paper # 88.
Schroeder, R.R. 2010. Lead fishing tackle: The case for regulation in
Washington State. MS Thesis. Olympia, WA: Evergreen State
College.
Schummer, M.L., I. Fife, S.A. Petrie, and S.S. Badzinski. 2011.
Artifact ingestion in sea ducks wintering at northeastern Lake
Ontario. Waterbirds 34: 51–58.
Sears, J. 1988. Regional and seasonal variations in lead poisoning in
the mute swan Cygnus olor in relation to the distribution of lead
and lead weights, in the Thames area, England. Biological
Conservation 46: 115–134.
Sears, J. 1989. Feeding activity and body condition of mute swans
Cygnus olor in rural and urban areas of a lowland river system.
Wildfowl 40: 88–98.
Sears, A., and J. Hunt. 1991. Lead poisoning in mute swans, Cygnus
olor, in England.InProceedings of the third IWRB international
swan symposium, eds. J. Sears, and P. Bacon. Wildfowl
Supplement 1: 383–388.
Sidor, I.F., M.A. Pokras, A.R. Major, R. Poppenga, and R.M. Miconi.
2003. Mortality of the common loon in New England, 1988 to
2000. Journal of Wildlife Diseases 39: 306–315.
Spray, C., and H. Milne. 1988. The incidence of lead poisoning
among whooper and mute swans Cygnus cygnus and C. olor in
Scotland. Biological Conservation 44: 265–281.
Stern, P., T. Dietz, L. Kalof, and G. Guagano. 1999. A value-belief-
norm theory of support for social movements: The case of
environmental concern. Human Ecology Review 6: 81–97.
Stone, W.B., and J.C. Okoniewski. 2001. Necropsy findings and
environmental contaminants in common loons from New York.
Journal of Wildlife Diseases 37: 178–184.
Strom, S.M., J.A. Langenberg, N.K. Businga, and J.K. Batten. 2009.
Lead exposure in Wisconsin birds. In Ingestion of lead from
spent ammunition: Implications for wildlife and humans, eds.
R.T. Watson, M. Fuller, M. Pokras, and W.G. Hunt. Boise, ID:
The Peregrine Fund. https://doi.org/10.4080/ilsa.2009.0104.
Stroud, D.A. 2015. Regulation of some sources of lead poisoning: A
brief review. In Proceedings of the Oxford lead symposium, eds.
R.J. Delahay and C.J. Spray, 8–26. Oxford: Edward Grey
Institute.
Thomas, V.G. 2019. Chemical compositional standards for non-lead
hunting ammunition and fishing weights. In Lead in hunting
ammunition: Persistent problems and solutions, eds.
N. Kanstrup, V.G. Thomas, and A.D. Fox, Ambio vol. 48,
Special Issue. https://doi.org/10.1007/s13280-018-1124-x.
Thomas, V.G, N. Kanstrup, and C. Gremse. 2015. Key questions and
responses regarding the transition to use of lead-free ammuni-
tion. In Proceedings of the Oxford lead symposium. Lead
123 Royal Swedish Academy of Sciences 2019
www.kva.se/en
Ambio

ammunition: Understanding and minimising the risks to human
and environmental health. Edward Grey Institute, The University
of Oxford. http://www.oxfordleadsymposium.info/wp-content/
uploads/OLS_proceedings/papers/OLS_proceedings_thomas_
kanstrup_gremse.pdf.
Thomas, V.G., and R. Guitart. 2003. Lead pollution from shooting
and angling, and a common regulative approach. Environmental
Policy and Law 33: 143–149.
Thomas, V.G. 1997. Attitudes and issues preventing bans on toxic
lead shot and sinkers in North America and Europe. Environ-
mental Values 6: 185–199.
Trust, K.A., M.W. Miller, J.K. Ringelman, and I.M. Orme. 1990.
Effects of ingested lead on antibody production in mallards
(Anas platyrhynchos). Journal of Wildlife Diseases 26: 316–322.
Twiss, M.P. 1997. Preventing lead poisoning of Ontario’s piscivorous
birds through policy and regulative reform. MS Thesis. Univ. of
Guelph, Ontario, Canada.
Twiss, M.P., and V.G. Thomas. 1998. Preventing fishing-sinker-
induced lead poisoning of common loons through Canadian
policy and regulative reform. Journal of Environmental Man-
agement 53: 49–59.
Tyrrell, R. 2015. Lead weights. In Heybridge: A late iron age and
Roman settlement, excavations at Elms Farm 1993-5 eds.
M. Atkinson and S.J. Preston. Internet Archaeology 40. http://
dx.doi.org/10.11141/ia.40.1.tyrrell8.
USEPA (Environmental Protection Agency). 1994. Lead fishing
sinkers; response to citizens’ petition and proposed ban;
proposed rule, 40 CFR part 745. Federal Register 59:
11122–11143.
USFWS (US Fish and Wildlife Service). 1986. Final supplemental
environmental impact statement on the use of lead shot for
hunting migratory birds. Office of Migratory Bird Management,
FES 86-16.
Vaske, J.J., and M. Manfredo. 2012. Social psychological consider-
ations in wildlife management. In Human dimensions of wildlife
management, 2nd ed., eds. D.J. Decker, S.J. Riley, and W.F.
Siemer. Baltimore, MD: The Johns Hopkins University Press.
Walker, R.E. 1981. Malleus and podagra: Lead poisoning in horse
and man. Veterinary History 1: 118–136.
Wani, A.L., A. Ara, and J.A. Usmani. 2015. Lead toxicity: A review.
Interdisciplinary Toxicology 8: 55–64.
WHO (World Health Organization). 2009. Global health risks:
Mortality and burden of disease attributable to selected major
risks. Geneva, CH. https://www.who.int/healthinfo/global_
burden_disease/GlobalHealthRisks_report_full.pdf.
Windingstad, R.M., S.M. Kerr, L.N. Locke, and J.J. Hurt. 1984. Lead
poisoning of sandhill cranes (Grus canadensis). Prairie Natu-
ralist 16: 21–24.
Wood, K.A., M.J. Brown, R.L. Cromie, G.M. Hilton, C. Mackenzie,
J.L. Newth, D.J. Pain, C.M. Perrins, et al. 2019. Regulation of
lead fishing weights results in mute swan population recovery.
Biological Conservation 230: 67–74.
Zabka, T.S., M.M. Haulena, B. Puschner, F.M.D. Gulland, P.A.
Conrad, and L.J. Lowenstine. 2006. Acute lead toxicosis in a
harbor seal (Phoca vitulina richardsi) consequent to ingestion of
a lead fishing sinker. Journal of Wildlife Diseases 42: 651–657.
Publisher’s Note Springer Nature remains neutral with regard to
jurisdictional claims in published maps and institutional affiliations.
AUTHOR BIOGRAPHIES
Tiffany Grade (&) is a biologist at the Loon Preservation Com-
mittee (LPC). Her research interests include causes of mortality in
loons, particularly issues related to lead fishing tackle mortality, and
impacts of contaminants on loon survival and breeding success.
Address: Loon Preservation Committee (LPC), P.O. Box 604,
Moultonborough, NH 03254, USA.
e-mail: tgrade@loon.org
Pamela Campbell is a Principal at ToxEcology – Environmental
Consulting Ltd. Research interests include chemical risk assessment
and risk management, chemical lifecycle and cost–benefit analyses,
and science-based policy development.
Address: ToxEcology – Environmental Consulting Ltd., 204-53 West
Hastings St, Vancouver, BC V6B 1G4, USA.
Address: Vancouver, Canada.
e-mail: campbellpm@toxecology.com
Thomas Cooley is a Wildlife Biologist/Pathologist at Michigan
Department of Natural Resources. His research interests include
wildlife disease/pathology.
Address: Michigan Department of Natural Resources Wildlife Dis-
ease Lab, 4125 Beaumont Rd, Lansing, MI 48910, USA.
e-mail: cooleyt2@michigan.gov
Michelle Kneeland is a veterinarian and Director of the Wildlife
Health Program at Biodiversity Research Institute. Her research
interests include implementing a One Health approach to wildlife
health, and network building among professionals across the realms
of human, environmental, and wildlife health.
Address: Wildlife Health Program, Biodiversity Research Institute,
276 Canco Road, Portland, ME 04103, USA.
e-mail: mkneel02@gmail.com
Elaine Leslie is Chief of Biological Resources for the US National
Park Service, overseeing wildlife conservation and health, at-risk
species, non-native species and their impacts, landscape-level
restoration and issues affecting ecological integrity in the national
park system. Elaine has long been involved in issues of lead toxicity,
including work on California condors, bald and golden eagles.
Address: Biological Resources, Natural Resource Stewardship and
Science, National Park Service, 1201 Oakridge Drive Suite 200, Fort
Collins, CO 80525, USA.
e-mail: elaine_leslie@nps.gov
Brooke MacDonald is a master’s student in Ecology and Environ-
mental Sciences at the University of Maine, Orono. Her research
interests are in applied ecology and human dimensions of conserva-
tion biology and resource management.
Address: Department of Ecology and Environmental Sciences,
University of Maine, 251 Nutting Hall, Orono, ME 04469, USA.
e-mail: brooke.hafford@maine.edu
Julie Melotti is a Laboratory Technician with the Michigan
Department of Natural Resources, Wildlife Disease Laboratory
(WDL). Her duties include performing gross necropsies on birds and
mammals for cause of death determinations, monitoring reports of
sick and dead wildlife from the public, and conducting disease
surveillance for bovine tuberculosis and chronic wasting disease.
Address: Michigan Department of Natural Resources Wildlife Dis-
ease Lab, 4125 Beaumont Rd, Lansing, MI 48910, USA.
e-mail: melottij@michigan.gov
Joseph Okoniewski is a wildlife biologist recently retired after
37 years of necropsies and investigations. Research interests included
the effects of environmental contaminants on wildlife.
Address: New York State Department of Environmental Conserva-
tion, Wildlife Health Unit, 108 Game Farm Road, Delmar, NY 12009,
USA.
e-mail: joseph.okoniewski@dec.ny.gov
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Elizabeth Jane Parmley is a veterinarian and epidemiologist. She works
in surveillance programs, risk assessments, and wildlife conservation and
management projects. Research interests include emerging threats and
opportunities at the human–animal-environmental interface.
Address: Canadian Wildlife Health Cooperative, University of Guelph,
Guelph, ON N1G 2W1, USA.
e-mail: jparmley@uoguelph.ca
Cyndi Perry is a biologist, retired from the US Fish & Wildlife
Service. She serves on the Board of Directors of the Wildlife Center
of Virginia. Her research interests include working in communities to
understand the challenges they face while living in close connection
with wildlife and how they can benefit.
Address: US Fish & Wildlife Service, Wildlife Center of Virginia,
Waynesboro, VA 22980, USA.
Address: Oakton, USA.
e-mail: cmperry353@gmail.com
Harry Vogel is a Senior Biologist/Executive Director at the Loon
Preservation Committee. His research interests include effects of
anthropogenic stressors on loon survival and reproductive success,
and efficacy of management and education to mitigate stressors and
recover loon populations.
Address: Loon Preservation Committee (LPC), P.O. Box 604,
Moultonborough, NH 03254, USA.
e-mail: hvogel@loon.org
Mark Pokras is an Associate Professor Emeritus at the Cummings
School of Veterinary Medicine at Tufts University. His research
interests include medicine and surgery of native wildlife, birds as
indicators of environmental health, and conservation biology.
Address: Wildlife Clinic & Center for Conservation Medicine,
Cummings School of Veterinary Medicine, Tufts University, North
Grafton, MA 01536, USA.
e-mail: mark.pokras@tufts.edu
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