Greymouth Star, 12 November, 2019. By Laura MillsAn angling group today warned people not to eat any trout caught downstream of the Maruia 1080 poison drop, after 680 rat carcases were washed up on North Beach at Westport at the weekend. The Department of Conservation is currently awaiting the results of toxicology tests on the rats, and some birds and fish also found dead on the beach.
The rats are believed to have been swept down the Buller River after the aerial poison drop a week ago was followed by torrential rain in the headwaters.
Health authorities say that because the rivers are still in flood, no one will be catching sports fish. However, NZ Federation of Freshwater Anglers president, veterinarian Dr Peter Trolove, said people should not eat trout downstream of Maruia for some time.
He called for more research on the effects of 1080 on fish. “Early studies were not conducted for long enough,” Dr Trolove said.
Trout could consume a reasonable dose and not show clinical signs of the toxin, he said.
“I would urge extreme caution,” he said to anglers.
Dr Trolove said the Government advice to wait a week after a 1080 drop was based on Cawthron Institute tests, which had fed the trout under half a pellet to replicate bykill.
However, he had seen trout taking full pellets. He personally had caught a trout in South Westland more than three months after a winter 1080 drop, and the fish was “blue in its gut” from the poison.
West Coast medical officer of health Dr Cheryl Brunton, who signs off on all 1080 operations, said today the rivers were in flood and no one would be catching fish anyway.
She noted it was not yet known what had killed the rats. “It will be interesting to see what the results are.”
DOC South Island operations director Mark Davies said trout were known to eat mice, but not rats, which were typically much bigger than mice.
If people had concerns, they should follow Ministry for Primary Industries advice to anglers to avoid eating trout from water ways in a 1080 operation area for seven days after the operation. The aerial poison operation in the Maruia valley was completed on November 3. “People need to take a precautionary approach with dogs, which are susceptible to poisoning from 1080. With their propensity to scavenge, people do need to be careful and keep their dogs super vised on leads or keep dogs away from affected beaches until the results of the toxicology tests come back,” Mr Davies said. People should also be cautious when handling dead rats. “If they do contain toxin, naturally occurring bacteria will break this down over time as the carcases disintegrate — there is no threat to human health.” In 2014, DOC issued warnings after the independent Cawthron research found the food safety risk from fish was higher than expected. Two years later, MPI advised a seven-day stand-down. Alan Simmons from the NZ Outdoors Party said today thousands of “poison laden time bombs” had been swept 140km downstream in Buller. “There are likely to be rotting and poisoned animal bodies all the way down the Buller River, ready to kill family pets, moreporks, trout, seagulls and any other creature that eats the carcases,” Mr Simmons said. In 2017 deer carcases were found on a beach in Southland, poisoned possums washed up on Dunedin beaches, and warning signs were recently put on Taranaki beaches after poisoned carcases were found scattered along the coastline, he said.