Although ingestion of Pb shotgun pellets was for many years the main source of elevated Pb exposure and poisoning for waterfowl and most other birds, for some species (e.g., common loons, Gavia immer) ingestion of small Pb fishing weights (sinkers and jigs) is a more frequent cause of Pb poisoning. A 'sinker' is an object, usually made of Pb, fastened to a fishing line in order to sink the line; a 'jig' is a weighted hook used as part of a lure to catch fish. Globally, thousands oftons ofPb in the form offishing weights are lost or discarded annually. Wildlife, primarily piscivorous birds and other water birds, sometimes ingest these items and suffer Pb poisoning as a result. Empirical evidence indicates that small (<30 g) Pb sinkers and jigs present the greatest potential for ingestion; however, almost all sinkers and jigs contain more than enough Pb to poison and kill water birds. In eastern North America, Pb poisoning from sinker or jig ingestion can be a major source of mortality for adult common loons during the breeding season in habitats that experience high recreational angling pressure, accounting for an average of about 20-30% of total reported mortality in these environments. In North America, in addition to loons, individuals of more than 20 species of wildlife (mainly water bird species) have been documented to ingest fishing sinkers and/or jigs. In Great Britain, extensive Pb poisoning of swans from sinker ingestion led to a regulation prohibiting the sale of small (<28.35 g or 1 oz) Pb fishing weights. Since the ban on Pb sinkers, mute swan (Cygnus olor) numbers, which had been declining in Britain, have increased dramatically. A few other jurisdictions (Canada, Denmark, and some US states) have also established regulations prohibiting the use or sale of some Pb types and sizes of fishing weights.
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