Sorry to say this since I have some friends which are dealers too, but
wouldn't it be an effective way of reducing shell harvesting to avoid
buying shells?
To obtain ten perfect specimens we see on dealers list probably 100 have
been killed and then passed through careful selection by local and western
dealers.  This is especially true in third world countries.
If you, careful and responsible collector, go anywhere to collect it is
likely you will kill much less animals than if you buy exactly the same
shells of the same quality from a dealer.

I strongly support self collecting, whatever method you use most collectors
will take much more care than any poor third world fisherman (or greedy
"first world" diver), and I am generally annoyed by total bans even if I
understand that SOMEwhere and SOMEtimes are a must.

I have just finished to read the great Vermeij's book "A natural history of
shells". I strongly suggest it to all of you.
This book gave me another point of view about shell collecting.  Not only
just a group of shells put in drawers to admire their beauty and "having
fun" giving them names and especially *new* names, but a great way to
understand evolution mechanisms, shells distribution, shell form and
molluscan behaviour.
I think this makes the collector loosing interest in gem specimens and in
the desperate search of rare shells, and improves its attempts to
understand their life and so Nature in general.

Best regards,
Paolo