The almost cpmplete extirmination of the ruddy duck,(originally an introduced species) from the UK has been extremely contoversial. The reason for this cull was its propensity to breed with the white headed duck(an endangered species of the same genus) and its migratory behaviour, especially as regards Spain, where most of the European population of white headed ducks remain. This culling was initiated by DEFRA, at the taxpayers' expense, supported by the RSPB(amongst others), and was so successful that to date the number has been reduced from 6500 to less than 10. My own position is that the cull was particularly pointless and expensive, especially as ruddy ducks have spread to other European countries(especially France) which, afik, have no such culls in mind.
As regards the OP, I certainly favour the phasing out of lead shot. Alternatives, I'm sure, can be found, as was the use of lead shot by fisherman.
However I can see that there are compelling arguments for the culling of certain species in certain environments.