A man who wished only to be known as Garry said he was one of about "about 30 or 40 people camping" at the lake reserve when the cullings took place.
"Two helicopters were flying along for a good hour and a half or two hours shooting.
"The only thing I'm complaining about is they should have picked them up."
Garry estimated hundreds of geese were shot and said he had seen "dead bodies everywhere".
"A lot of people would have enjoyed eating them. In Tauranga people were allowed to pick them up [after a culling]."
Ann Hazlewood of Featherston said she had counted 19 dead birds when she had visited the lake late Tuesday afternoon to walk her dogs.
"My main concern was with the long weekend coming up and with the weather we're having they would start stinking."
She said the public should have been informed about the culling before it happened.
Charlie Matthews, of Waiorongomai Station, was one of a group of farmers who organised the cull.
He said, after Monday's efforts, about 15 people had gone around the lake collecting the birds.
"We make a very concerted effort to pick them up in public places," he said.
"It's really difficult because they're shot over the lake and it was an easterly. They got blown over to the western side.
"We tried to pick up all we could.
"[On Tuesday] it was a southerly so some must have pushed to the north end, which we weren't aware of.
"We physically can't pick up every bird -- but we do our best."
Canada geese are considered a pest species.
"They cause destruction for us and cause a hell of a mess," Mr Matthews said.
They remain in flocks year round, are aggressive and noisy, and destroy pastures and crops with their droppings.
An open season on the birds means they are unrestricted and can be shot at anytime, all year round.
"I'm sorry the public have had to see the dead animals.
"I'm sorry for the people who have seen them while camping," Mr Matthews said.
After Mr Matthews' phone conversation with the Times-Age on Wednesday evening he promptly organised a team to retrieve additional dead geese that had washed up.