Hatcheries

Lessons learned at Arno, Likiep clam farm facilities

"Although the function of the hatcheries is to supply clam seedlings to interested local farmers, they also serve as research stations with the objective of increasing giant clam populations."

HIGHLIGHT

Tridacna Maxima

The Coastal Fisheries Division performed extensive rehabilitation on two of its hatcheries so that they were returned to its full operation. Raceway tanks were repaired, saltwater pumps installed, and a total of four sessions of successful artificial spawning of Tridacna Maxima have been carried out with production ranging from five-to-ten million fertilized eggs per tank. Though results from each spawning session produced a substantial number of fetilized eggs, high mortality rate has been an ongoing issue.

Further investigation revealed that over-crowding occurs when the 1,350 gallon concrete raceway tanks are occupied by up to ten million giant clam larvae per tank, which generates competition for space and food resulting in higher mortality.

To resolve this issue, MIMRA staff worked to determine suitable concentration of larvae that will limit mortality yet yield appropriate number of seed clams. The required adjustment to the rearing methodology and application of the existing density procedure formulated by MIMRA's previous counterpart OFCF. To fully address the situation, additional tanks are needed to provide space for larval rearing and seed settlement.Currently, Existing tanks are split between larval rearing and clam seed settlement, which does not provide adequate space for successfully producing clams. Additional settlement tanks will allow the current production number, which is roughly 350,000 juvenile clams per year, to double. Separate larval rearing tanks will allow the hatcheries to produce clam seeds continuously.

A density control scheme is now being applied for spawning trials while MIMRA works gradually toward constructing new larval rearing tanks.

In the meantime, following renovations to the Arno and Likiep hatcheries, recruitment of local giant clam farmers in Arno was carried out by hatchery staff through community meetings. At Likiep Atoll, local farmers have established their own association called Likiep Atoll Aquaculture Association with a membership of 183 local farmers.

The Association's charter was approved by the Office of the Attorney General in November 2014. This enables the Association to apply for grants to expand aquaculture projects and possibly to handle their own exporting and marketing in the foreseeable future.

The Coastal Fisheries Division continues to provide technical assistance where needed.

Although the function of the hatcheries is to supply clam seedlings to interested local farmers, they also serve as research stations with the objective of increasing giant clam population through stock enhancement and reseeding (conservation efforts).

The Coastal Fisheries Division maintains its commitment to promote aquaculture to other atolls and islands as a source of economic development in these communities.

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