margaritifera recruitment during the study and these were generally sites with relatively turbid water. margaritifera at any site was 8.61 ± 0.30 cm while the smallest was 4.26 ± 0.13 cm. The largest mean dorso-ventral measurement (DVM) of P. margaritifera juveniles were collected from all sites with the highest number of recruits (693) and the highest number of recruits per collector (2.10 ± 0.17) occurring at Nacobau (Vanua Levu). Spat collectors were deployed for a period of 10–15 months when the number of pearl oyster ( Pinctada margaritifera and Pteria penguin) spat attached to each collector was counted and shell size recorded. Spat collectors consisted of a 100 m longline from which 310 individual spat collectors were suspended. Twenty-nine sites across Fiji were used in this study. This supply can be inconsistent and a research program was implemented to determine recruitment of pearl oysters to spat collectors at sites throughout Fiji as a basis for developing a national spat collection program to improve reliability of oyster supply to the industry. To receive more information on oyster seed collection or the purchase of hatchery seed, please give us a call or send us a message using the form below (or to the right).Cultured pearl farming in Fiji relies on wild spat collection to supply the oysters used for pearl production. Just as an Upweller, the Downweller is designed to aid in the growth of juvenile oysters. The downward flow of water provides essential nutrients for the setting oysters. This promotes rapid growth of the spat.Īlong with providing essential nutrients, a FLUPSY can protect oyster seed from predators, competition from other shellfish and biofouling in the early stages of development.Ī Downweller System provides hatchery operations with a clean substrate and proper environment nylon mesh, finely crushed shell (microcultch) or another suitable material. In a FLUPSY, the seed sit in silos and are fed a constant flow of naturally occurring nutrients called phytoplankton from the upwell of water that the structure generates. To aid in the growth of juvenile oysters before they’re ready to be transferred to grow-out equipment, producers are beginning to adopt the use of an Upweller or FLUPSY (Floating Upweller System). Upwellers (FLUPSY) and Downweller Systems Most hatcheries are now offering triploid oyster seed, given the benefits. They can be harvested at any time, including the summer months (depending on local conditions). Triploids do not spawn and continue to grow throughout the year. Invented in 1979 by Standish Allen, triploid oysters have three sets of chromosomes which making them sterile. Technological advances have been made to develop non-spawning oysters. Using hatchery spat allows oyster Farmers to cut down on labour costs while beginning the growing process with healthy, certified seed that are resistant to disease. Hatchery spat are grown in laboratory conditions and fed nutrients that can enhance growth. In most all situations, the collector is covered in a thin layer of a cement, lime and sand mixture to assist in setting. The use of these methods is subject to an oyster Aquaculturist’s own personal preference in collection, depending on the conditions in the area.
Oyster spat collector trays are used primarily on tidal flats to collect seed in the intertidal zone.
Long lines and raft culture are other methods of collection. More modern methods of seed collection include using oyster (Chinese) hats, coupelles, and modified drain pipes. Although still widely used, these methods of tradition collection leave the oysters susceptible to predators in the wild and have made way for more advanced options for oyster seed collection. They have been a mainstay in Australian and Japanese oyster farming for centuries. Oyster sticks are another method of traditional seed collection in the wild as well as in hatcheries. These oyster beds are most often situated in an intertidal zone to prevent fouling and strengthen the abductor muscles of the oysters. Over time, spat (oyster seed) settle on the empty oyster shells, maturing to a harvestable size. On-bottom traditional seed collection includes the spreading of cultch, recycled oyster shells, on the sea bed. Oyster seed collection can occur in a variety of ways.
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