No health risks to people, say the experts
Ngongotaha residents have been burying dead ducks found on the shores of Lake Rotorua, and experts say the birds are likely to have died of botulism.
Steve Wynn and his neighbour, Grahame Haggart, found the dead and sick birds behind their lakefront properties on Tuesday. Mr Wynn reported it to the Rotorua Lakes Council and the Bay of Plenty Regional Council and the issue is now being investigated by Fish & Game Eastern Region office.
"I first picked up two dead and four crook ones and took them into the SPCA. Only one from the SPCA has survived," Mr Wynn said. "I've been further around near the [Ngongotaha] stream mouth with a wheel barrow and collected 19 [ducks] all up and a couple of seagulls. I buried them in the neighbour's offal pit.
"This happened three years ago but nowhere near this extent. It only lasted 24 hours. It's not really nice seeing this. One of the ones that died, we had been seeing it since it was a chick [duckling] - it was a light candy colour and, all through winter, it would come up to the door."
Mr Haggart said he was concerned for the health of others who might use the waterways.
"Kids often come down to the jetty and swim and people fish for trout, catch them, smoke them and eat it. There should at least be signs up warning people to stay away from the water," he said.
He thought the low water level of the lake might also be contributing to the deaths.
"I've lived here 15 years and this is the lowest I've seen the lake. It's down a good [metre].
"You can't launch boats at the jetty because it's too shallow."
Fish & Game regional manager Andy Garrick said they had two or three reports of the issue so far but would continue to investigate.
He didn't believe there were any health risks to people.
"It's very likely to be botulism. The warm conditions are favourable for it and it often affects game birds such as mallards. Most years we have small outbreaks but it is typical in a dry summer where the stagnant water is lying around in calm conditions.
"We usually have isolated or localised incidents so we hope it's not going grow into anything."
Mr Garrick did not recommend people to swim in water with dead ducks around and encouraged them to wear gloves if they were handling the birds. If birds were sick the best treatment was to put them in the shade somewhere where they had access to fresh, clean water. If they were going to survive, they generally came right in two to three days.
SPCA Rotorua office manager Nadine Brown said the duck they had treated this week was to be released last night.
"If someone finds a sick duck it is better to call us rather than bring them in and we can discuss the problem over the phone," she said.