Hoiho numbers plummet

Conservationists are calling for more marine reserves along the Catlins coastline to protect declining numbers of yellow-eyed penguins. By Kerrie Waterworth

"The northern [mainland] population of hoiho has declined 83% since 1996 to just 163 breeding pairs in 2023. Conservationists fear it could become extinct by 2060."

A new record was set at Forest & Bird’s Te Rere hoiho penguin sanctuary last spring, but it was no cause for celebration. 

During the October nest search, the Department of Conservation and Forest & Bird team found only two nests in the Catlins penguin reserve, a record low for the start of the season. 

“We had the lowest numbers, the worst outlook we have ever had,” said Te Rere manager Brian Rance. 

A third nest was later discovered, and the season ended up with three nests, still the lowest on record, although three chicks hatched and survived. 

When Brian first started volunteering at the Te Rere hoiho sanctuary in 1986, there were 50 pairs and more than 100 penguins. After a devastating fire at the reserve, numbers settled at about 20 pairs, but in 2010 the numbers started diving. 

There are currently an estimated 10 adult penguins in the colony, and numbers have been declining since 2015 (see graph overleaf). “We hope our monthly pest line checks keep the predator numbers low and remove one threat to our hoiho. It’s tragic putting in this big effort, when something bad seems to happen [to the hoiho] every year, and they don’t have a chance to recover,” added Brian. 

Ōwaka-based Department of Conservation biodiversity ranger Cheryl Pullar carried out weekly checks of Te Rere’s two nests during the breeding season. 

In December, she uplifted two “very underweight” chicks for rehabilitation from one nest. 

The second nest was found to have one infertile egg and an egg that hatched very late. The one-day-old chick that weighed just 79g (chicks usually weigh 90g at hatch) was taken to Dunedin’s Wildlife Hospital. All three chicks survived and were later released at Long Point, another hoiho breeding colony in the Catlins.

Mainland hoiho breed along the south-eastern coast of Te Waipounamu South Island, from Banks Peninsula to North Otago, Otago Peninsula, Catlins, Rakiura Stewart Island, and neighbouring Whenua Hou Codfish Island. 

Cheryl said Te Rere was not alone in experiencing a population decline. There were reduced nest numbers all along the Catlins coast this year (see overleaf). 

Breeding adults sometimes take a year off breeding if conditions are not ideal, but the causes of decline over the last 10 years have been primarily attributed to starvation, diseases such as avian diphtheria, and injuries sustained at sea. 

“Te Rere reserve is closed to the public, has an extensive trapping network, and has undergone restoration planting for a couple of decades,” said Cheryl. 

“Land-based issues are being addressed. It’s the marine environment and unknown triggers for disease that are problematic.” 

Rachel Hickcox attaching a GPS device to an adult hoiho. Image Supplied

University of Otago marine conservation ecologist Dr Rachel Hickcox tracked mainland and Stewart Island hoiho to estimate their nesting range and marine foraging range, and “to figure out what is going on at sea”. 

She found hoiho foraged in areas used by all types of fisheries along the South Island’s eastern continental shelf and continued to be at risk of drowning in gillnets. 

In her PhD, completed last August, Rachel concluded: “Current fisheries management practices are not sufficiently reducing protected species captures and protecting the marine environment, despite quota management and vessel monitoring systems, electronic catch reporting, and increased observer and camera coverage on inshore vessels… 

“Marine protection is required in fisheries–penguin interaction hotspots including the Catlins coast and North Otago.” 

Last October, the previous government announced the first new marine reserves in the south-east of the South Island, following years of public consultation. 

But the new marine reserves are in Otago and will leave most of the Catlins and Southland hoiho unprotected. Otago marine ecologist Thomas Mattern has been researching hoiho for more than two decades and will be working with the species again on Rakiura next summer.

Two penguins in the bush at Te Rere, where Forest & Bird volunteers have been carrying out predator control since the 1980s. Image Fergus Sutherland

He said the new marine reserves would protect only 4% of the predicted range of the yellow-eyed penguins. 

“We have been sitting on our hands too long,” he said, “Even if we established substantial marine reserves off the Otago and Southland coast tomorrow to protect hoiho, there is a good chance the Catlins population has gone past the point of no return already. 

“If we had found a way to reduce the fisheries impacts, I think hoiho might have had a fighting chance.” 

Hoiho are predicted to be extinct on the mainland of New Zealand by 2060. 

“The first scientific publication pointing out the significant impact of set net bycatch on the species was published 24 years ago. That should have been a major wake-up call,” added Thomas. 

“But here we are a quarter century later with next to no change in our fishing practices.”

Graphic showing trawling intensity around Te Rere (red = highest intensity). Image supplied

HALTING THE DECLINE

Forest & Bird asked Richard Seed, DOC’s Senior Ranger for Coastal Species (Otago, Southland and Rakiura), for his analysis on how our mainland (northern) hoiho are doing.

The northern population of hoiho, currently breeding from Rakiura to North Otago, has declined 83% since its recorded peak, dropping from an estimated 949 breeding pairs in 1996 to an estimated 163 pairs in 2023. 

Historically, periods of decline for the northern population were followed by recovery. This is no longer the case, despite management efforts. 

The goal set out in Te Kaweka Takohaka mō te Hoiho (the Hoiho Recovery Strategy 2019) was to halt the decline of the northern hoiho population in five years. 

Despite extensive action to implement this recovery strategy, the decline has continued. The strategy is due for a review in 2024/25. Starvation and susceptibility to disease have been the main reason for recent declines.

INSERT GRAPH: Mainland hoiho: Snapshot of the last three seasons

The northern population of hoiho requires intervention to ensure they survive. This intervention has intensified in recent years to include uplift of young chicks for disease treatment for around seven days, supplementary feeding of chicks through to fledging, supplementary feeding of adults and juveniles to ensure they survive the annual moult, and treatment of any sickness or injury that threatens survival.

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The intensive management programme relies on the significant efforts, expertise, and facilities of the Wildlife Hospital Dunedin, Penguin Rescue, OPERA (Otago Peninsula Eco Restoration Alliance), and the Yellow-eyed Penguin Trust, in addition to those of DOC. 

Our intervention efforts improve fledging success and survival of juvenile and adult hoiho. However, this operation is limited to protecting birds that are closely monitored on land. We lose too many birds outside of this sphere of control. 

Continuing to implement other aspects of Te Kaweka Takohaka mō te Hoiho and its five-year Action Plan Te Mahere Rima Tau are essential to halt the decline. 

These include mitigating fisheries bycatch, protecting the marine habitat, reducing disturbance from unregulated tourism, and protection from terrestrial predators, including dogs.

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