A once-thriving population of little penguins on a tourist island off Perth’s coast has plummeted to no more than 120 birds, with plans to build a container port in nearby foraging grounds further threatening the survival of the colony.
The latest population study on Penguin Island – 600 metres offshore and 50km south of Perth city – has revealed that penguin numbers have crashed by two-thirds in the past five years, sources say.
The little penguin population, called Weedee in Noongar, has declined by 92% since 2007.
A scientific report, commissioned by the local Rockingham council and detailing the extent of the problem, was provided to the council in late April before being passed to the state government. Guardian Australia has repeatedly requested the report, but neither office has made the findings public.
Since 2012, researchers have been sounding the alarm about the penguins, which have been ravaged by boat strikes, parasitic infections and marine heatwaves that have robbed them of their preferred prey fish.
In 2017 the population nosedived by a quarter to 518, according to the University of Western Australia biologist Belinda Cannell, who also wrote the new report.
In 2021 the penguins endured a horror breeding season in which half the chicks died, leaving behind an ageing breeding population.
“Without informed management, we will very likely lose this genetically important population of little penguins,” Cannell said in January.
Scientists working on the island, including Cannell, declined to comment on the latest report until it was released.
For decades, research and management documents have shown that tourism can affect the breeding success of little penguins, Eudyptula minor.
Erin Clitheroe, a biologist at Murdoch University, said it was death by a thousand cuts for the penguins, with tourism not the only pressure, but one that could be managed.
Boats bring visitors to the island every 20 minutes between mid-October and June, unless the temperature climbs above 35C. The access period has been shortened in recent years as the population went into freefall.
Advocates have proposed that the island be closed to tourists throughout the year.
The WA environment minister, Reece Whitby, said the major factor in the population decline was the warming sea temperature. He cited measures the government had put in place to protect the penguins, including the winter closure period, the scrapping of a planned discovery centre on the island and the installation of 125 artificial nest boxes.
“Tourism plays an important role on the island by educating visitors about the penguins and promoting enjoyment of our state’s natural environment,” he said.
But Dawn Jecks, a City of Rockingham councillor and convener of Save the Little Penguins, said Whitby’s department had carried out building work on the island for five years, and needed to do more to protect the penguins from marine traffic.
“We have a management plan for the island that is 22 years out of date, 22% of the birds are dying from boat strike, and gangs of jet skis are speeding and doing rings around Penguin Island in a wildlife conservation zone,” she said.
WA’s Department of Biodiversity, Conservation and Attractions said the research commissioned by the council was “vital”, but it would not comment on the population report before it was published.
It said the department had increased patrols of the waterways around the islands, among other measures.
Plans for nearby container port
As well as human activity and the changing climate, the colony faces a new challenge in plans to relocate Fremantle’s container port to Kwinana, opposite Garden Island and extending into Cockburn Sound, where some of the Penguin Island birds forage.
Garden Island, a naval base off-limits to the public, is home to a second colony of little penguins that feed exclusively in Cockburn Sound.
To make the port big enough for container ships, parts of the sound would have to be dredged, affecting fish stocks.
The federal government has committed $33.5m towards developing the $4bn Westport project, which includes a freight road, rail and logistics operations for the port.
Westport said the port would be the most sustainable in Australia and that it had partnered with the Western Australian Marine Science Institute to provide $13.5m to study Cockburn Sound.
“This work has already resulted in a decision to move the port footprint 1km south to avoid any direct impact to seagrass beds in Cockburn Sound, and a design that will minimise impacts to the marine environment,” a Westport spokesperson said.
In a study published for Westport last December, Cannell found that both colonies of little penguins would be affected by dredging through loss of food sources, noise and reduced ability to see predators.
The 15-year project has been referred for the highest level of environmental assessment through WA’s independent Environmental Protection Authority.
The WA Greens MP and former Fremantle mayor Brad Pettitt said the government should follow the evidence of what the port would mean for wildlife populations.
“Government is proceeding as if Westport is a given, despite their own reports revealing some very major impacts from that project on the health of the sound, including on penguin and fish populations.
“It is industrialisation of Cockburn Sound.”
• This story was corrected on 17 May 2024 to give accurate dates for island visits.
