For the 7th time this year, a dead whale has washed up on Portuguese beach north of San Francisco in Sonoma County, Calif.

A gray whale measuring about 28 feet long that was not yet fully grown was found dead on the beach — and no one knows what happened that caused it to die, according to a CBS Local report.

May marks the end of the migration period for gray whales as they head north after breeding off the coast of Mexico. Another dead gray whale was found in Half Moon Bay earlier this week near Kelly Beach — that one was about 30 feet long.

Over the last five weeks, there have been seven dead whales, and officials have had to scramble to get rid of the decomposing bodies by burying due to the overpowering smell the engulfs the area.

A 48-foot male sperm whale was found washed up on a beach in Pacific on April 14, and another whale was found nearby on May 4. Officials say it’s just a coincidence that they were found so close together.

A killer whale was found beached north of Fort Bragg back on April 21st, prompting scientists to flock to the area as it’s rare to find killer whales beached. They so far don’t have any answers on how it happened.

Two gray whale carcasses were found April 24 on Santa Cruz County Beach, and a 40-foot gray was found near Waddell Beach.

One 23-foot young whale found at Pajaro Dunes appeared to have teeth marks from a killer whale, and it had lost its tongue and jaw, indicating it probably died from an attack by an orca.

A pygmy sperm whale was found dead at Point Reyes National Seashore back in January.