Some years ago, lead shot under a certain size was banned for use so far as fishing was concerned in the UK. Larger sizes were permitted on the basis that wildfowl would not ingest it
There is no doubt that wildfowl will die if they injest lead, at least l have read enough evidence from the data to support that. However l can only say this that many of the places the wildfowl would visit in the UK winter periods were also areas that they were hunted over, marshland and areas like that.
On the other hand we have a very high population of Swans in the UK and that bird can reach way down to feed off the bottom. There was again here sufficient evidence to prove that Swans had dyed because of injested lead shot. They are a protected species. Shot of course for a cartridge is not cut like shot for fishing purposes, so that was also a way to substantiate the source. Fisherman, however that would relate more to use by course fisherman and not fly fishers !!.
What are my views about that. If l thought that l was causing a species to die because of the use, then l would not do it.
On another note l also believe that the recovery rate of wildfowl shot with material other than lead is too high. I have seen far too many birds wounded fly off, perhaps to die at a later point in time. I have hunted wildfowl all my life and at one time owned a hunting operation for that purpose, no doubt at all in my mind about the ratio of harvested birds to wounded, when lead was used. it was considerably higher.
I do not know what if any data as yet has been recorded for this, and l would like to see it if there is any.
In this scenario l would say that the use of non toxic substances are more detremental than the use of lead, which may become injested. Better to recover 6 birds shot at as opposed to 12 shot at and 6 wounded, which may or may not recover.