Most of the geese that were killed were Canadian geese. They eat the grass around the lakes and produce an excessive amount of poop. The geese were reproducing quickly, and their large numbers were becoming a problem. They also damaged local crops and put pressure on local species.
"We didn't do this whole-heartedly", says Hendrik Moeremans of Natuurpunt. "But we had to take up our responsibility."
Hunters' organisations would have preferred to shoot the animals. They fail to understand why gassing the geese is so much better. They also say that now, a lot of meat is being wasted, as it can't be used for consumption. This would have been possible if they animals had been shot. Moeremans says that using guns to each one of the geese, would have had a negative impact on local nature.