The Basic Methods of Pearl Farming: A Layman's Manual - CTSA

Basic Methods of Pearl FarmingBlack-Lip pearl oysters spend their adult lives attached to hard substrates by the byssal threads. Beforethe pearling boom of the late 1800s and early 1900s, they were extremely common and are reported tohave thickly covered large areas of reef, including inter-tidal areas. They are now rare in many placesas a result of overfishing, and are most common at depths below 60 ft. Pearl oysters are gregarious,meaning that they tend to be found in groups, both as juveniles and adults.Pearl oysters are protandric hemaphrodites, which means that most are first male, then female. Themale phase usually occurs during the first 2-3 years of life, with the change to the female phase in lateryears. Pearl oysters have been reported to live as long as 25 years. Pearl oysters reproduce by releasingmillions of eggs or sperm into the water column, where fertilization occurs randomly. In less than 24hours, the fertilized egg develops into a trocophore larva, a free-swimming organism (Figure 5). Thelarvae remain suspended in the water column for 2-3 weeks before undergoing metamorphosis, changinginto an attached juvenile “spat.” Shortly before metamorphosis, the larva develops an enlarged footand an eye-spot. The foot remains after metamorphosis, and the young spat retains the ability to moveabout for several months even after it attaches itself to a hard substrate. Pearl oysters can attach andreattach themselves using the byssus.Figure 5. The life cycle of the pearl oyster.Page 10