It’s only the second time in history that the ocean salmon fishery has been closed in California, and the decision reflects a major decline in fish populations after the state’s driest three-year period on record.

Local officials and scientists have yet to nail down how many fish have died, but the reports have been coming in non-stop since Friday.

The carcass of a 41-foot adult female gray whale landed at San Francisco’s Crissy Field on March 31. A second adult female was found April 3 at Moss Beach in San Mateo County. A third was found April 7 floating near the Berkeley Marina and the following day another at Muir Beach. A video of the fifth dead whale was posted on social media Friday.

The carcasses of four gray whales have been found around the San Francisco Bay Area in eight days -- an alarming string of deaths that constitutes an unusual mortality event, defined by the National Oceanic and Atmospheric Administration (NOAA) as a significant die-off of a marine species.

A gray whale carcass washed ashore at Crissy Field on Wednesday morning. Veterinarians and biologists from the center and from the California Academy of Sciences plan to perform a necropsy in coming days on the island to determine the cause of death.

The Marine Mammal Center and California Academy of Sciences are reporting cause of death for one.