A disease which caused respiratory distress syndrome (RDS) in chicks, combined with a marine heatwave, killed half the penguins hatched at Katiki Point Reserve last year.
Now it appears RDS is back and it may be worse than last year.
Penguin Rescue manager Rosalie Goldsworthy said last year’s season was an "absolute disaster". Chicks had died just over 10 days old but some had died this season when only 3 days old. Fewer than 10 chicks had died this season.
The chicks were taken to Dunedin when they were about 3 days old, where they would stay until they were 300g in weight, usually around 5 to 7 days old. Adults were being given dummy eggs while their chicks were in Dunedin.
Diphtheria — a bacterial infection which prevents feeding and causes dehydration — used to be the biggest problem when Ms Goldsworthy first started 21 years ago.
Now it was RDS, she said.
She hoped this season would be better for the critically endangered birds. She paid tribute to the hospital, which she said was doing a wonderful job.
The birds were the first to hatch in Otago this season, so the future for the rest of the summer in other parts of Otago was unclear.
The El Nino weather pattern was typically good for penguins because the currents brought water from Antarctica that was full of nutrients, she said.
The yellow-eyed penguin colony in Moeraki was the largest in the country and has space for up to 50 penguins to hatch.
It accounted for 26 of the 120 nests across the mainland.
The penguins needed to be looked after to save them from extinction, she said.