I stumbled across this interesting video over on the Reef2Reef Forums the other day. It’s an older video, though recently uploaded, that shows how Tridacnid clams are farmed. This Palau facility uses the nearby ocean as a major area for growing the broodstock clams, with the land-based portion reserved for breeding, juvenile grow out, and larvae rearing.
The most interesting portion of the video demonstrated how the facility’s staff induced clam spawning events. They would pick a mature clam, cut out its gonads (of course killing that individual), and squeeze the gonads near the incurrent siphons of sexual mature clams. This action would release horomones into the water, causing the clams to almost instantly release a cloud of sperm. Being hermaphroditic, the clams would later release eggs as well. The clams releasing eggs would be removed from the tank and placed into individual containers, where egg capture would be much easier. The fertilized eggs would then be loosely counted and placed into a large holding tank where the larvae would mature. The larvae would settle onto the bottom of the tank, where they would acquire Zooxanthellae and continue developing. After approximately 12 months, the clams would be available for market, which consists of the aquarium trade, replenishing local reefs, and even the Japanese sushi market to name a few.