Marine biologists are trying to figure out why eight harbour porpoises have washed ashore near Victoria in the past week.

The most recent carcass was found on the beach near Beacon Hill Park Tuesday.

It's not unusual for harbour porpoises to wash ashore, but it's strange to see so many, according to the Department of Fisheries and Oceans.

Marine biologists examine the body of the eighth harbour porpoise to wash ashore in the Victoria area in the past week. (CBC) "There's no external trauma, so there's nothing obvious," said Larry Paike, DFO's manager in Victoria.

"The animals are healthy. They're fat. They've got good musculature. So, it's not like they're suffering from some debilitating disease."

Paike said the porpoises usually die as a result of being hunted by killer whales. If they are not actually killed by the whales, the porpoises die from the stress of being hunted.

Remains to be analyzed

The fact that the animal found today was pregnant also could have been a factor.

"The onset of the breeding season means a lot more energy expenditure," marine biologist Anna Hall told CBC News. "Animals that are not as strong simply don't survive."

Young offspring of all types of marine mammals also are vulnerable in the wild.

The body of a newborn killer whale washed up near Victoria last week.

The carcasses of all the dead animals have been sent to a laboratory in Abbotsford, B.C., southeast of Vancouver, for analysis, said Paike.

He said tissue samples will be taken to find out whether toxins played a role in their deaths.

With files from the CBC's Lisa Cordasco and Lisa Johnson