An injured and severely underweight penguin was treated at Vetlife Timaru and has since been moved to the Oamaru Blue Penguin Colony for further treatment.

A severely underweight yellow-eyed penguin found in Timaru with a long, deep gash in the webbing of each foot likely only had days to live when it was found and taken to a veterinary practice.

"It's really good that people can keep an eye on the beaches because ordinarily this bird would have died," Oamaru Blue Penguin Colony research scientist Philippa Agnew said.

"This is why it's so important that people don't touch the penguins but contact DOC [the Department of Conservation] straight away."

Vetlife's Timaru branch - which saw the injured penguin brought in on Friday - posted on Facebook saying it had started the bird on antibiotics, cleaned its wounds, and given it fluids via a tube and under the skin. It was sent to Oamaru on Saturday for further care.

Agnew said the bird would go on to Dunedin's Wildlife Hospital if surgery was required, a decision she would make after reassessing the bird following rehydration and weight gain.

"They're specialists in wild birds and have really fantastic knowledge about what to do next," she said.

Yellow-eyed penguins usually weigh in at 5kg but the one currently in Agnew's care, a juvenile that only hatched earlier this year, was worryingly underweight at 2.7kg.

"It's going to take a bit of time to get it up to its normal body weight," she said.

"It will be at least two or three weeks."

The bird's wounds were not uncommon and the causes were being researched, she said.

"One theory is that the cuts are caused by barracuda bites."

She was unsure how the injuries, which were not fresh when the bird was found and looked to be at least a few days old, were sustained.

She described the wounds as "severe" but was hopeful the bird would survive, and was planning to release it at the Bushy Beach Scenic Reserve in Oamaru, where there is a yellow-eyed penguin colony, once it was fully recovered.