Researchers say a newborn calf from B.C.'s endangered killer whale population has died.

The Center for Whale Research, based in Friday Harbor, Wash., says the calf was alive for a few hours before it died Tuesday.

Victoria-based skipper Mark Malleson said he saw something unusual among a group of orcas Tuesday morning near San Juan Island, Wash., close to the international border.

"I looked through the binoculars and I saw that there was a new calf swimming with them," Malleson said. "Then, as I got the angle turned so I could actually see the saddle patch with the binoculars, [I] realized we've got resident killer whales."

He alerted the Center for Whale Research. Researchers arrived to find the the mother, J-35, balancing her baby on her nose trying to keep it afloat.

But her newborn was dead.

"Having a newborn, there were a few moments of brief, brief happiness, and then followed by disappointment and sadness," said Dr. Anna Hall, a marine biologist with the Center for Whale Research.

"This is a population that is clearly struggling in terms of numbers."

The southern resident killer whale population is a group of three orca pods that live around the coast of Oregon, Washington and Vancouver Island. Their primary food source is salmon, particularly chinook salmon.

After the death of a 23-year-old orca known as "Crewser" in mid-June, the total number of southern resident killer whales is down to 75, which is the lowest count since the early 1980s. The population has dropped by eight since 2016.

Researchers believe one of the reasons for the fall in population is the decline in Fraser River chinook salmon.

In May, the federal government announced plans to cut the allowable catch of chinook by 25 to 35 per cent.

In June, it announced further measures to help the endangered resident killer whale population including reducing underwater vessel noise and better monitoring pollution.

"I think there is always hope. We have to remember wild animals can be quite resilient when the threat factors are removed or the situation changes," Hall said.

The last successful southern resident killer whale birth took place three years ago. A 2017 study by the University of Washington found that more than two-thirds of orca pregnancies among the group failed over a seven-year period.