Scientists are to check whether New Zealand muttonbirds that spend the winter off the coast of Japan have been exposed to radiation from the damaged Fukushima nuclear power plant.

In a new pilot study, University of Auckland scientists will investigate whether radioactive cesium has entered the New Zealand ecosystem or food chain via the birds.

The wrecked plant and its trapped contents have loomed over Japan since floodwaters from the March 2011 tsunami knocked out the plant's back-up generators that were supposed to keep cooling its nuclear fuel.

The over-heating sparked meltdowns in three reactors and forced 150,000 to flee, and tens of thousands have been unable to return home to areas contaminated by radiation.


In the study, researchers will test the birds' feathers for gamma rays that indicate the presence of the radioactive isotope cesium-134.

Feathers will be collected from prime muttonbird sites in the South Island, particularly Stewart Island.

New Zealand sooty shearwaters or titi migrate annually, spending the summer mating and raising their chicks in New Zealand before over-wintering off the coast of Japan.

Dr David Krofcheck, of the university's department of physics, said the research was "very much about taking a precautionary approach" as there was no evidence to indicate that the birds had been vectors of radioactivity.

"But detection of gamma rays would tell us whether the birds spend sufficient time near Fukushima to accumulate cesium-134 from nuclear fission," he said.

"Obviously the issue would then become whether that radioactivity is being absorbed into local ecosystems or the food chain."

Pacific Bluefin tuna caught off the west coast of the United States showed only a minute trace of cesium-134 from Fukushima, 100 times less than normal radioactive elements found in fish.

The sooty shearwater was of cultural and economic value to Maori, who sustainably harvested the nearly fledged chicks during the annual muttonbird season.


The season runs from April to May and was restricted to Maori and their whanau who use the birds for food, oil and feather down.

Dr Krofcheck said consultation with Maori, the Rakiura Titi Islands Administering Body, about the research would begin as soon as possible.

"We will need to go through a number of approval processes and engage in consultation with local people before anything can happen as there are sensitive issues to consider before work can begin."

The research is being done in collaboration with the Department of Zoology, University of Otago.

Radiation at Fukushima's power plant has declined to acceptable levels. Photo / AP
Radiation at Fukushima's power plant has declined to acceptable levels. Photo / AP

Previous tests on muttonbird exposure to radiation from Fukushima found no evidence of cesium being passed from parents to chicks.

"Our study is complementary to that earlier work but tests feathers instead of the birds themselves," Dr Krofcheck said.

"Obviously what we are hoping to find in this latest research is that cesium levels in muttonbirds do not exceed exposure levels you would expect from natural sources."