VANCOUVER, British Columbia - Hundreds of starfish have been found dead on a beach on British Columbia's Sunshine Coast, and a scientist says a nonnative parasite is likely to blame.

Purple sea stars began washing up last week in Trail Bay at Sechelt, north of Vancouver. The Canadian Department of Fisheries and Oceans has been unable to determine why they died, agency spokeswoman Michelle Imbeau said.

Bruce Leighton, a marine parasite expert at Simon Fraser University in Burnaby, noted Wednesday that the die-off coincided with the peak of the starfish reproductive cycle, when the creatures are most vulnerable to Orchitophrya stellarum, a protozoan that feeds on sea stars' sperm.

He said the parasite is believed responsible for wiping out purple sea stars in North Vancouver's Indian Arm and eliminating much of the male population of the species in other areas of British Columbia, altering the balance of species.

The parasite is native to the Atlantic but is now found along the British Columbia and Washington state coast, possibly after arriving in ship ballast water or with seafood. East Coast starfish usually survive infestations, scientists said.

Sea stars feed on mussels and barnacles, making more room in the intertidal zone for other creatures that support other marine and bird life and thus helping to maintain biodiversity, Leighton said.