A dead, juvenile gray whale washed up on the Sonoma Coast this weekend at Portuguese Beach.

The 28-foot whale appeared to have been dead for some time and was in a state of obvious decomposition, according to California State Parks Ranger Damien Jones.

He said the carcass came ashore Friday night or Saturday morning. The Marine Mammal Center took a tissue sample in an attempt to determine cause of death, but it did not to appear to be from trauma, he said, such as being struck by a ship.

Jones said State Parks did not plan to remove the whale from the beach, which is about halfway between Jenner and Bodega Bay. He said the tide could carry it out to sea again.

“Generally we leave dead and sick animals where they are and let nature take its course,” he said.

May is the tail end of the gray whale northern migration from their breeding and birthing lagoons in Mexico back to their feeding grounds in Alaska. Although thousands of whales make the approximate 5,000-mile journey, including the newborn calves and their mothers, some of the cetaceans, especially juveniles, are believed to stay closer year-round to a more confined area.

There has been a series of dead whales washing up on Northern California beaches over the past five weeks.

A 40-foot dead gray whale was found Monday near Half Moon Bay.

On May 4, a 42-foot female humpback whale was found near Pacifica. A 48-foot sperm whale was found April 14 in the same general vicinity.

On April 24, two gray whale carcasses washed up on a Santa Cruz County beach, including a 40-foot adult gray whale. The other, a 23-foot yearling, had killer whale teeth marks on its body and other evidence of an Orca attack.

A killer whale carcass was found near Fort Bragg on April 18, and the Noyo Center for Marine Science in Fort Bragg said Saturday another gray whale had washed up in Mendocino this week.