A dead killer whale calf that washed up on a Vancouver Island beach west of Victoria was not from B.C.'s southern resident orca population.

The remains were found near Sooke, B.C., on May 4 and scientists say DNA shows the calf belonged to the transient population of whales.

Vancouver Aquarium senior mammal scientist Lance Barrett-Lennard says the death of any young whale is always troubling but researchers are relieved the calf is not from the critically endangered southern resident pods.

He says every death in the southern resident group moves it "closer to a breaking point."

Transient orcas feed exclusively on other marine mammals, not fish, and Barrett-Lennard says that means the whales accumulate large amounts of organic pollutants in their bodies, passing the toxins to their calves during birth.

Transient orca calves have just a 60 per cent survival rate in their first six months and a necropsy shows the 220-kilogram calf was just a day or two old and had partially inflated lungs when it died.