She would provide a proper assessment in the next few days, he said.
Although the 40cm-wide bite to the sea lion's side was deep, the bite wound had not punctured the animal's abdominal cavity, which would have been problematic.
Ahead of the prognosis from the wildlife vet, Doc remained optimistic the roughly 6-year-old male sea lion would survive.
The untagged animal was "not out of the woods" yet and infection remained a real issue.
Doc asked the public to continue to report sightings of the animal as it planned to track its progress for the next few weeks.
A member of the public reported seeing the sea lion with flesh bitten out of its side at Allans Beach about 4.30pm on Friday.
A photo was sent to Doc's marine technical adviser, Clinton Duffy, who advised that the bite mark looked to be from a large great white shark.
Volunteers went to look for the sea lion on Saturday, but it was not found.
Despite its massive injury, the 2m-long male had gone back into the water, Fyfe said.
New Zealand Sea Lion Trust chairwoman Jordana Whyte said the incident highlighted the fact the animals faced pressures in the marine environment, and they needed undisturbed rest on Dunedin beaches.
Sea lions were known to survive these incidents and some sported "serious battle wounds", but sea lions were a food source for great white sharks, she said.
"That sea lion is already a survivor, because it got away from that shark," she said.
"If that guy hadn't had his proper rest he might not have gotten away from that shark."
At the weekend, surfers at Allans Beach were cautioned they could be sharing the water with a large visiting shark.
Great white sharks are known to be resident at Stewart Island but are considered visitors to the Otago coast as well.
A sign was installed at the beach at the weekend stating a shark could be in the area, Fyfe said.
"We know there's obviously a fairly big shark in the area, and we can alert people locally that we've seen the result of a recent visit and give anybody who is considering surfing out in that area the option of making an educated choice about their actions," he said.
• Department of Conservation: 0800 DOC HOT (0800 362-468)
• Shark sightings: sharks@doc.govt.nz
