James Whitford (right), Project Scientist ACIAR, James Cook University Pearl Oyster
Resource Development Project and Beero Tioti, Assistant Fisheries Officer, Nursery Manager.
Photo: Genevieve Johnson
February 6, 2001
Blacklip Pearl Fishery
This is Genevieve Johnson speaking to you from Tarawa atoll.
Fishing in the sea is comparable to hunting on land, it is easy to
overharvest populations of wild animals. As a result, populations of many
wild fish and shellfish are rapidly declining, while production of
aquaculture is increasing. Aquaculture is the farming of marine and
species in captivity. Today some of the crew were given a tour of the
Blacklip Pearl Oyster
Nursery in south Tarawa.
Black pearl oyster shells and cultured pearls are a potential source of
export income here.
A collaborative project between Australia and Kiribati has been established.
The objective is to assist Kiribati in developing an industry for culturing
Blacklip pearls. Low technology hatchery and nursery culture methods have
been developed during the first phase of the project. It is hoped that the
oysters will yield their first viable harvest of black pearls in 2002.
James Whitford is the Project scientist for the Pearl Oyster Resource
"Seeding is done by stressing the oyster out, What they will do is stress them out by crowding them close together and the oysters get weak. When the oysters get weak they will be opened with a pair of reverse pliers, they call it a shell opener, it's a special tool. It's inserted into the oyster and they place a wedge inside, the farm hands will open all the oysters up to a gape of about one centimeter, or a centimeter and a half. The technician whose operating on them, places the oyster into a tray and he inserts what is called a 'nucleus' made out of shell, mainly from the Mississippi River at the moment and pig muscle.
The idea is then that the piece of tissue from the donor oyster will grow into a sac around the bead that has been put inside the gonad, and after a year and a half to two years, that sac secretes the nacre onto the bead. So a cultured pearl usually has one to two millimeter of nacre covering over a shell bead, and that is what is marketed as a cultured pearl not an artificial pearl.
We hang culture units off the long line, we hang the oysters at a depth of about one or two meters from the surface. Depending how big they are, we first deploy them in the nets and then in plastic crates, which are about one meter by half a meter. Once the animals reach ten to twenty millimeters in diameter we put them into what we call pocket nets which tend to be a meter by forty or fifty centimeters, which are sown to form pockets.
The idea is to start generating an industry based around the hatchery, so the hatchery will be extended and micro farms developed where you have one thousand shells in a family situation on an outer island. On paper it looks like those people will be able to cover a bank loan of twenty-five thousand dollars after three years. They will be in possession of a substantial amount of infrastructure, a boat and a long line for growing the pearl oysters. They will then be able to start increasing that every three years by about five thousand dollars. The next three years, thirty thousand and the boat and equipment should last about ten years. They will have a chance to reinvest into oysters, which the government will have to produce under some sort of arrangement and increase the size of their farms."
A Black pearl oyster shell.
Photo: Genevieve Johnson
The Japanese are also funding hatcheries for sea cucumber and trochus snails
in Kiribati, projects similar to that of the blacklip pearl fishery, these
are also in the testing and development stages. Aquaculture may appear
simple but it requires regular maintenance of an environment conducive to
growth, including the eradication of predators and algae, control of
diseases, and the stability of temperature light and salinity. Three
different food types are currently being tested on a single species of
cucumber to establish the fastest rate of growth, therefore the highest rate
of production. The sea cucumbers will be grown and harvested as a food
source for the Japanese market. The trochus snails are grown in large tanks
where they feed on algae. Their shells are in high demand in Japan where
they are used to make buttons.
These fisheries are examples of the aquaculture programs being implemented
in the South Pacific
Log by Genevieve Johnson