Fewer than 190 breeding pairs were counted on the Otago coast this season...down from 500 in 2012!
Many chicks were hit by avian diphtheria, an infection that forms ulcers in chicks' mouths, making it difficult to eat and breathe. Some chicks had died due to overheating, as they remained under the protection of their parent's body.
Coastal Otago Biodiversity Ranger Mel Young: "There's no obvious pattern to the infection outbreak, but most infected chicks have also been underweight. The heat has played a large part too."
Ailing penguins have been fed salmon smoothies every few days, and had the lesions in their mouths removed, allowing them to eat and breathe easier. Despite this, about 45% of chicks at monitored sites had died.
Tourists visiting those sites have also caused problems. The Department of Conservation (DoC) urges them to take established tours, rather than explore on their own, so as not to disturb breeding.
It's a sentiment echoed by the Yellow-Eyed Penguin Trust GM Sue Murray: "The penguins have had a tough four breeding seasons, so we're trying to minimise every possible risk, to give them their best chance of survival."
Penguins face many dangers - disease, interference from humans and livestock at breeding areas, heat stress, predation by stoats and ferrets, and dog attacks.
In 2013, a mass mortality event believed to be a toxic bloom, killed around 70 adults and juveniles on the Otago Peninsula. Also that year, low food supplies left penguins emaciated and unable to moult without help.
Early in 2015, 50+ penguins were maimed in barracuda attacks.