In Cornish folklore, the sea spirit fishermen propitiated for good catches was the Bucca.
The Bucca is a male sea spirit or merman associated with Cornwall’s coastal communities. Folklore recorded offerings of fish or part of the catch being left on beaches, especially around Newlyn and Mousehole, to keep the spirit favourable. The practice reflects a bargain familiar from maritime traditions: fishermen acknowledged a dangerous supernatural power in hopes of receiving protection or abundance.
Stories give the Bucca both helpful and threatening qualities. In one Lamorna tradition, the Sea Bucca drives fish into nets and crabs into pots, yet can take terrible revenge when offended. Cornish accounts also distinguish a benevolent Bucca Gwidden, or White Bucca, from the darker Bucca Dhu.
The Bucca is sometimes compared with the Irish púca and Welsh pwca because the names and traditions are related. It should not be confused with a knocker, the subterranean spirit associated with Cornish mines, or a spriggan, another type of Cornish supernatural being.