Dear Masashi,

Thank you very much for the informative post.  You illustrate very
well what I was suggesting, that it is the harvesting of molluscs
for food or commercial purposes--on a large scale--that cause
the populations to be stressed, and not scientific collecting.

Cheers,


Don

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> From: Masashi Yamaguchi <[log in to unmask]>
> To: [log in to unmask]
> Subject: Re: Images and pictures...
> Date: Saturday, April 22, 2000 1:15 AM
>
> Dear Frank,
>
> Marine molluscan resources on Okinawa have been subjected to intensive exploitation or
over-harvesting
> after you were enjoying reef walks at low tides only a couple of decades ago. When the
locals collected
> shells for home consumption during low tide periods, these molluscan populations had
plenty time for
> restocking by themselves. Things are all different now, because professional fishers
use diving gears and
> other advanced means of exploitation such as an underwater torch (that can make the
whole sea bottoms
> visible around the divers for easy catch of nocturnally active species). Once the
brood-stocks were decimated
> it is very hard for reef dwellers to come back. There have been government-funded
projects to restock these
> molluscs (giant clams, green snail and trochus), but it takes a long looong time to get
them increased and
> to be self-propagating. The small giant clam (T. crocea) restocking project was
initiated in the early 1970s
> and juveniles produced in the government hatcheries have been planted on the reefs in
many hundred of
> thousands so far, but the recovery is very slow. The trochus project followed and
juvenile releases have
> been underway but we must wait for several years to see the results, as they grow to
maturity very slowly.
> The green snail project is the most recent since its life cycle was not known until the
late 1980s. Juvenile
> mass-production has been established for this snail and releasing methods are under
investigation.
> It is so easy to destroy molluscan stocks of commercial value but very hard to restore
after destruction.
>
> Masashi Yamaguchi
> Univ. of the Ryukyus,
> on Okinawa