6.2.4 Receiving the eyed larvae

Mature larvae are shipped from the hatchery to the remote setting site. Two million mature Pacific oyster larvae form a ball about 5 cm in diameter when wrapped in mesh (Figure 89). Once received, they are placed in a plastic bucket with 10 l of water at 20 to 25°C and allowed to acclimate for fifteen to thirty minutes.

The contents of the bucket are then poured into the tank. The number of larvae added per tank depends on size of the tank and the amount of cultch but as a “rule of thumb” 1 300 to 2 200 larvae are added per 2 m length of plastic pipe and about 100 larvae are added per piece of shell cultch. Air is turned on for about thirty minutes to ensure thorough mixing of larvae in the tank and is then turned off to allow the larvae to attach to the cultch. If pipe cultch is used, only half the larvae may be added originally and after one day the pipe modules are flipped and the remainder of the larvae are added. This helps create an even set on all surfaces of the pipe.