Yes, all the Tridacnidae are on the endangered list internationally, and
the U.S. supports that and prohibits import.  There are exceptions for
molluscs grown in aquaculture.  There are a number of places that can
export them under this exception, including the Solomon Islands which
advertises them on a home page.  There are a growing number of places
that grow them commercially for food, with a portion set aside to
restock the reefs.
 
While some species are seen in normal quantity in some places, there are
many places where they have been reduced to near extinction.  Caused by
collection for local food, and collection by outsiders for export of
food, and some shells.  Palau is a good example of the over collection
by commercial outsiders.
 
The Philippines which prohibits export of all Tricdacnas still allows
exceptions for exports under some controls, but they want to see that
all benefits come to Philippinos.
 
Aloha,
 
Wes