<P> Pearl hunting is the act of recovering pearls from oysters in the sea . Pearl hunting used to be prevalent in the Persian Gulf region and Japan . </P> <P> Before the beginning of the 20th century, the only means of obtaining pearls was by manually gathering very large numbers of pearl oysters or mussels from the ocean floor or lake or river bottom . The bivalves were then brought to the surface, opened, and the tissues searched . More than a ton were searched in order to find at least 3 - 4 quality pearls . </P> <P> In order to find enough pearl oysters, free - divers were often forced to descend to depths of over 100 feet on a single breath, exposing them to the dangers of hostile creatures, waves, eye damage, and drowning, often as a result of shallow water blackout on resurfacing . Because of the difficulty of diving and the unpredictable nature of natural pearl growth in pearl oysters, pearls of the time were extremely rare and of varying quality . The Great Depression in the United States made it hard to get good prices for pearl shell . The natural pearls found from harvested oysters were a rare bonus for the divers . Many fabulous specimens were found over the years . By the 1930s, overharvesting had severely depleted the oyster beds . The government was forced to strictly regulate the harvest to prevent the oysters from becoming extinct, and the Mexican government banned all pearl harvesting from 1942 to 1963 . </P>

What type of oysters have pearls in them