The Spanish missionaries in the 1660s observed that the Chamorros believed the spirits (aniti) obliged them to keep silent during certain periods of fishing. Breaking this code of silence during the fishing would result in a bad catch, or some other punishment.
They also noted that Chamorros did not eat fish from the river. Safford thinks that this refers only to the fresh water eels (asuli). Many Chamorros looked down on the Spanish missionaries who ate these eels.