Lead Toxicity in Mute Swans

Swans
activity and a change in angling accessories initiated the problem of lead
poisoning in mute swans.
In Ireland, there are approximately 1000 coarse anglers (E. Parkes,,
pers. comm.). In addition, many coarse anglers visit Ireland to participate·
in international competition. However, as in England, little information is.
available on 'angling litter' discarded by anglers in this country. Recently_,
Bell et al. (1985) have researched the problem in south Wales. Angling
litter was compared from two sites, one a game fishery and the other a
coarse fishery. Considerable quantities of nylon monofilarnent line were
recovered from the game fishery, where anglers were found to drop, on
average, 2-3m of line per fishing trip. At the coarse fishery, less nylon
line was recovered. There -were, however, high densities of lead shot iin
the mud, with up to 125 shot m- 2 surface area in front of the fishing pegs.
It was estimated that more than 15, 000 lead shot (total weight 5kg) a're
deposited at the fishery (area 1 ha) each year. This represents 2-3 shot
dropped per fishing trip (Bell et al. 1985). Shot weights were in the range
0.03 to O.lOg (this corresponds to shot size 8 and SSG), and represent the
entire range of commercially available split shot. It is also interesting to
note that, on average, 75% of discarded shot which was recovered in the
sampling area was within lm of the bank. It is clear that such a density of
lead shot in the mud could pose a serious threat to waterfowl using the
site. The coarse angling density in Ireland is considerably lower, except
during infrequent international meetings, but it is essential that threats to
our waterfowl be minimised. In view of the fact that coarse angling is the
fastest growing aspect of the sport (E. Parkes, pers. comm.), it is
essential that alternatives to lead weights be used to protect our environment
and wildlife. --
To date, there are six non-toxic products on the market as alternatives
to lead weights. The criteria required are high density and cheapness;
details of alternatives are as follows:
1. Sandvik Safeweight: split weights and ledgers made from a tungstenbased
polymer.
2. Anglers' Weight by Evode: a tacky, rubber-based, powdered steel
mixture in convenient strips.
3. Saturn-shot: reusable zinc-plated steel weight, of various sizes, coloured
to resemble lead.
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