The term oyster pirate is rarely if ever encountered outside of accounts of the life of Jack London. It is often mentioned without any explanation ("he was a jailbird, sailor, seal-hunter, oyster pirate, novelist, laundry worker, yachtsman, and coal shoveler"), as if everyone knew the meaning of the term.

In the context of Jack London's life, it refers to a specific set of conditions peculiar to the oyster industry in San Francisco Bay in the 1880s. Native West coast oysters were greatly inferior to those from the East coast. When the transcontinental railroad was completed, the Southern Pacific Railroad leased land to entrepreneurs, who created artificial mud flats and grew oysters from transplanted Eastern stock.

Monopoly conditions led to exorbitant prices, creating an opportunity for the oyster pirates. The pirates raided the oyster beds at night and sold their take in the Oakland markets in the morning. The public disliked the Southern Pacific and the oyster growers, and liked cheap oysters. As a result, the oyster pirates had considerable public sympathy and police were reluctant to take action against them.

Jack London's described oyster piracy in his autobiographical "alcoholic memoirs", John Barleycorn; in the form of romanticized juvenile fiction in The Cruise of the Dazzler ; and from the opposing point of view of the California Fish Patrol in "A Raid on the Oyster Pirates," from Tales of the Fish Patrol .

"Oyster pirates" also operated in the Chesapeake Bay.