Dead red abalone and sea stars are being reported on the Sonoma County coast as officials from the California Department of Fish and Game try to determine the cause of the die-off.

The number of deaths is not known, but dead and dying abalone have been reported in Bodega Bay, Russian Gulch, Fort Ross, Timber Cove and Salt Point State Park.

Officials do not believe the deaths are being caused by Withering Syndrome, a disease known to have struck abalone populations in Central and Southern California.

The deaths have coincided with a local red tide bloom and calm ocean conditions — a combination that has been present during other die-offs, according to state officials.

State officials have collected abalone, mussels and water samples and continue to document reports from the public.

The abalone fishery remains open.

The public is asked to report the location, number and date of dead or dying abalone to Ian Taniguchi at (562) 342-7182.