Urgent Action Needed on Pesticides Wrecking Freshwater Ecosystems

A national trout fishing and environmental advocacy organisation wants urgent attention to insecticides that are almost certainly causing deep damage to freshwater ecosystems.

The call follows information from the US that a variety of neonicotinoid insecticides—harmful to aquatic organisms—were reported in major Great Lakes streams.

NZ Federation of Freshwater Anglers president Graham Carter said insecticides had widespread use in New Zealand. Trout anglers had over decades noticed strong declines in hatches of aquatic insects such as mayfly and caddisfly species.

“You could liken it to the canary in the coalmine scenario,” he said. “Trout and their food such as aquatic insects and anglers’ observations are out there and it just isn’t good.”

Last October, a global study of the presence of neonicotinoid pesticides found them present in all of the New Zealand honey that was tested.

The U.S. study was the first to examine the insecticides—gaining notoriety in recent years as a prime suspect in bee die-offs— in the world's largest freshwater system and suggests Great Lakes' fish, birds and entire ecosystems might be at risk.

In birds, exposure to the chemicals had been linked to population declines.

“It ends up going through the food chain,” commented Graham Carter. “Long term t’s about ecosystem poisons.”

Evidence was strong that chemicals may directly hurt aquatic wildlife—from tiny organisms to fish—with potential to disrupt entire ecosystems.

A leading US research chemist said the major risk of these chemicals was to aquatic insects—an effect that could ripple up the food chain.

Graham Carter said pesticides adversely affecting aquatic insects populations, removed the basic food source for fish.

‘We’re talking not just trout but native fish as well,” he said.

The US study revealed that a large percentage of the chemicals detected came from urban areas.

“This shows "urban use of pesticides has a substantial impact on the health of our rivers, streams and lakes,” he said. “We’re not talking just about farmers responsibility but town use too. It’s a total population responsibility.”

Graham Carter said Fish and Game NZ and the Department of Conservation (DOC) should have been alert to and active on the issue. DOC had responsibility for trout fisheries management in the Taupo region and country-wide for native fish. Ironically, he added, DOC was using an ecosystem poison in its widespread use of 1080 which was first developed in the 1920s as an insecticide. It also sanctioned 1080 use by agencies such as Tb-Free NZ.

“It’s not just a pest poison but an insecticide poison and therefore an ecosystem poison,” said Graham Carter.

He said the case for use of 1080 was lacking reality, logic and justification.

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