FAO Fisheries Technical Paper. No. 503
Pearl oyster health management
Melba G. Bondad-Reantaso, Sharon E. McGladdery and Franck C.J. Berthe
The pearl oyster industry is a growing multibillion dollar sector of mollusc aquaculture. Pearl farming occurs throughout Australasia, the Middle East and South America. Few species of molluscs possess the ability to produce pearls of gem quality. The South Sea pearl oyster is one of them. Pearl production in the wild is an unpredictable and uncontrolled event which human intervention, through pearl culture, has progressively overcome by improving culture practices. Farming mother-of-pearls shares commonalties with edible mollusc aquaculture. However, the endproduct, pearl production, is unique to this sector. In aquatic production, heal issues are of utmost importance; pearl production is based entirely upon health. The pearl itself is a product of the oyster’s immune defences as a response to soft-tissue irritation. Exploited stocks receive frequent handling stresses which often predispose farmed animals to infection and diseases. Therefore, the importance of health management for pearl oysters is paramount. Today, most disease problems are caused by opportunistic pathogens taking advantage of oysters weakened by the stress of handling, including pearl surgery and sub-optimal growing conditions. Except for the mass mortalities experienced in Japan, the pearl oyster industry have not yet faced the types of epizootics which has impacted mollusc culture elsewhere in the world. Development of the industry will, inevitably, lead to increased risk of disease introduction, spread or emergence. Against such an unwanted future, health management is the critical defence line.
The objectives of this technical paper are to: (i) review pearl oyster mortalities and disease problems in order to help design programmes aimed at reducing the risks from diseases; and (ii) provide technical guidance to pearl oyster farmers and the industry on management of pearl oyster health so that sector development will be sustainable not only in providing huge employment to communities where pearl farms are located but also contributing to maintain environmental integrity. Pearl oyster farming can serve as environmental sentinels recognizing the fact that pearl oysters thrive only in pristine environment.
This publication contains three parts. Part 1 consists of pearl oyster health — the current interest in it and an overview of the cultured marine pearl industry. Pan 2 on pearl oyster health management consists of seven sections, namely: (a) introduction; (b) general information on husbandry and handling, hatchery production, introductions and transfers; (c) disease diagnostic protocols dealing with field collections of samples, gross external examination, gross internal examination and laboratory protocols; (d) health zonation; (e) disease outbreak protocols; (f) national strategies on aquatic animal health; and (g) references. Certain countries in the pearl oyster producing regions have acquired a great deal of experience in health management of cultured species. Experiences from Australia, the Cook Islands, Japan, the French Polynesia, the Philippines, China, the Persian Gulf and the Red Sea are included in Part 3 which also contains a general review of pearl oyster mortalities and disease problems.