A slaughter of more than 12,000 Canada geese in Canterbury has led to complaints to Conservation Minister Kate Wilkinson.
The birds were culled this summer after the species was designated a pest in June.
A spokesperson for the minister says most of the complaints were about bird carcasses left on the shores of Lake Ellesmere.
But Federated Farmers, which was contracted to do the work, says 12,000 birds were killed at the lake and maybe a few dozen bodies went unrecovered.
Complainants say they are concerned at the way the birds were rounded up and clubbed on the head, and that lead shot was fired over the lake.
Ms Wilkinson has declined to comment.