A spate of baby penguin deaths has raised concerns there could be a repeat of a catastrophic breeding season of five years ago, when there were mass fatalities of kororā.
On Waiheke Island alone, seven baby penguins have been found emaciated and starving. One has had to be put down.
In the summer of 2017 to 2018, hundreds of penguin chicks died.
Native Bird Rescue on Waiheke Island is providing intensive care to the struggling underweight chicks, some of whom are as young as two weeks old.
Founder Karen Saunders told Checkpoint that conditions in the Hauraki Gulf this year are particularly grim for little kororā.
"In the Hauraki Gulf, we've got multiple factors. It's like the perfect storm comes together."
Climate change and rising sea temperature changes were part of it, but the gulf also had a real problem with overfishing, bottom trawling and the impacts that had, Saunders said.
"On land they also have habitat loss, cat, dog ... so many predators, so they face a really tough time," she said.
"On the mainland, most kororā are gone now so it's really the offshore islands where we really have population."
The young penguins at Native Bird Rescue are cared for with a special diet to get them up to strength.
"We make anchovy smoothies which is probably the worst bit of my whole job, if you can imagine an anchovy smoothie, it's pretty gross."
They feed them five times a day with three hours between feedings, starting at 7.30am and finishing about 9.30pm. Many of them are tube-fed.
Rising sea temperatures are having a dramatic impact on the penguin population, though, Saunders said.
"What we're seeing this year is pretty much all of the nests have been abandoned.
"We had a report this morning of seven dead penguins on Onetangi Beach, there were five yesterday, and we're seeing other seabirds starving as well."
The shallow surface feeders would be suffering this year, she said.
If people happen to see a kororā on the beach that looks abandoned, seek help from groups like Native Bird Rescue on Waiheke Island, Bird Rescue Aotearoa in Green Bay or the Department of Conservation.
"Any penguin that's out in the daytime on land is in trouble and needs help."
At the moment, not all penguins in Aotearoa were being affected - colleagues in Golden Bay were "having a bumper year," Saunders said.
"I think it's going to be the Hauraki Gulf and hopefully it won't be the rest of Northland as well.
"But, this is how it started in 2017 when we ... had thousands and thousands of penguins up the northeastern coastland dead.
"We're hoping it's not a repeat of that."