Set nets are a major cause of penguin deaths, affecting most of the world's species including New Zealand's hoiho, or yellow-eyed penguin.
Yellow-eyed penguins at Moeraki. Photo: AFP
A review of global research found 14 of the world's 18 species are affected, including three in New Zealand.
It identified the endangered hoiho, or yellow-eyed penguin, as one of three penguin species most under threat by the fishing equipment.
The study said set nets were estimated to kill on average 35 yellow-eyed penguins each year.
The deaths are a huge blow for a species that has only 246 breeding pairs in the South Island.
New Zealand scientist Ursula Ellenberg initiated the study published in the scientific journal Endangered Species Research.
She said the fine nylon mesh nets, set stationary in the water, were designed to catch fish around the gills but were just as capable of catching penguins around the neck.
"We had this last season eight little penguins caught in a single net - so a single set netter can do a lot of damage.
"In Tasmania we found nets with more than 50 little penguins drowned.
"Penguins are fantastic divers and visual hunters. They see very well but they just can't distinguish those invisible nets and then they swim into them and get entangled and drown in a matter of minutes."
Dr Ellenberg said the government must act urgently to save the hoiho from extinction.
"We've talked long enough, we need to act now" - Dr Ursula Ellenberg
Numbers had declined by 76 percent in the past 20 years. "Twenty years ago we had 400 nesting pairs on the Otago peninsula alone," Dr Ellenberg said.
Penguins are unable to see the nets under water so they get tangled in the mesh and drown. Photo: 123rf.com
She said more than 300 commercial fishing boats used the nets in New Zealand waters and it was time the Ministry for Primary Industries took action.
"We've talked long enough, we need to act now. We're losing them."
"With less than 250 nests left of the South Island, how hard can it be not to set a net where you're likely to catch a yellow-eyed penguin?".
Dr Ellenberg said the government must act urgently to save the hoiho from extinction.
A yellow-eyed penguin at Curio Bay, Southland. Photo: AFP
The head of Fisheries Inshore New Zealand (FINZ), Jeremy Helson, said penguins faced many threats, including climate change, habitat degradation, disease and predators.
"We agree that fishing does pose some risk to yellow-eyed penguins and industry takes a range of precautions to limit captures and is happy to discuss what measures can be implemented to assist further," he said.
"It is also important to note that government observers last year focused their effort on these set net fisheries, and with approximately 40 percent of observer coverage in yellow-eyed penguin habitat (the east and south coasts of the South Island) no captures of yellow-eyed penguins were recorded."