VICTORIA — Whale enthusiasts are celebrating the arrival of a colourful Christmas baby for the endangered southern resident killer whales.

The calf, with characteristic pinky-orange patches, was spotted Saturday in Puget Sound by National Oceanic and Atmospheric Administration researchers and the birth was confirmed Wednesday.

As the calf had fetal folds when the first photos were taken, it is likely it had been born only hours earlier.

"We are really pleased to have another calf in the population," said administration wildlife biologist Brad Hanson.

"The numbers are slowly creeping up, but they're still a concern. They can drop back down just by losing a couple of animals."

The new calf is the third born in 2011 and brings the population in the three pods, which cruise the coast of southern Vancouver Island and Washington State, to 89 animals.

However, mortality rates for calves can be up to 50 per cent, so everyone is keeping their fingers crossed that the J-Pod calf, known as J-48, will make it through the winter.

Odds should be stacked on the side of J-48, said Susan Berta of Orca Network.

Mother is 39-year-old J-16, known as Slick. Her previous four calves have survived.

"The first calf always gets the biggest off-loading of toxic chemicals so this one should be getting pretty clean milk," Berta said.

The reason that later calves do not get so many contaminants is that there is less time for the mother to accumulate toxins from food, Hanson said.

Chinook salmon, the primary food for resident killer whales, are heavily contaminated with pollutants such as PCBs and flame retardants.

Other populations of fish-eating killer whales, such as the northern residents and Alaska populations, are recovering faster than the southern residents and researchers are comparing notes and looking for reasons, Hanson said.

"We're continuing to work on all fronts to figure out what factors contribute to that," he said.

Canada's killer whale recovery plans have pointed to lack of chinook salmon, pollution and noise as major factors.

The historic population of southern resident killer whales is believed to have been about 120 animals. The low was in 1973, when, after decades of hunting and captures, the number fell to 71.