Experts say 1080-poisoned trout 'unlikely'
A national freshwater trout advocacy group is calling for anglers to avoid eating trout from southern areas where 1080 is dropped but the call has been rubbished by the scientific community.
The New Zealand Federation of Freshwater Anglers last week put a call out warning anglers to steer clear of trout caught from riverways near the latest Department of Conservation 1080 drops because of the possibility of secondary poisoning.
The call comes after DOC announced it planned a large aerial 1080 drop in response to an expected rat and stoat plague arising from a one in 10-15 year beech mast.
A large area in the Catlins is included in the plan.
New Zealand Federation of Freshwater Anglers president David Haynes said the planned 1080 bombardment of thousands of hectares of public land had failed to take into account mice ingesting 1080.
There was a high likelihood of massive secondary poisoning of trout and eels as the poison had a "secondary" property, he said.
Mice that ate 1080 and were then eaten by trout could have impacts on humans who ate the trout, he said.
However the scientific and some in the fishing community have dismissed the claims as largely unscientific.
Southland Fish and Game manager Maurice Rodway said it was "very unlikely" trout would be affected by 1080 poisoning.
"Anything is possible but I think it's pretty remote, pretty unlikely."
"In theory it's a possibility. They [the mice] could eat it and then get into the water and trout could eat several mice but by that stage the breakdown of 1080 would have occurred. There's certainly a lot of complexities in it, [but] I don't think it's a real risk."
Otago University associate professor of zoology Gerry Closs, a specialist in freshwater fish, echoed this viewpoint. "I think it's very unlikely. Long shot after long shot, that would be my feeling."
While not an expert on toxicology, he was experienced in studying trout and freshwater fish and he was not aware of any instances where they had been poisoned by 1080, he said.
However, Mr Haynes said the risk factor lay in the lack of research on secondary poisoning of trout by 1080.
"It's well known that trout eat mice. Given some mice do eat 1080 and die from it and trout do focus on mice, what research is being done on secondary poisoning.
"Our concerns are, primarily, is it going to make us sick and, secondly, is it going to kill the trout?"
DOC spokesman Rory Newsam said research indicated little evidence of any significant poisoning risk for humans through eating trout or eels after 1080 operations.
"Unlike mammals like possums or rats, fish are not at significant risk from 1080."
He was surprised by the claim by the anglers group as they did not seem to be supported by science, he said. There was some research conducted by the National Institute of Water and Atmospheric Research that showed there were no significant biological impacts on freshwater fish, he said.
"The risk is so low it's minimal. The benefits far outweigh any risk."
The Southland Times