application of the ownership principle laid
down in the FA0 definition of aquaculture
helps to make reasonably accurate
distinctions. Therefore, the results of stock
enhancement efforts, which have reached
huge proportions in Japan, are not reported
as aquaculture.
Mollusc culture is still almost entirely
dependent on collected seed, although
hatchery technologies are available for
the most important cultured species. The
high fecundity of commercially important
bivalves makes mass collection of spat
feasible in all those areas where breeding
stocks of the required species are not yet
depleted. Thanks to the hardy nature of
juveniles of most species, long distance
transport of seed from good breeding
grounds to depleted ones is also feasible.
However, in the case of some species (e.g.,
abalones, scallops), availability of natural
seed is limited. Pioneering mollusc
hatcheries are now in operation in some
countries ofthe region but seed production
from these hatcheries, although feasible
technically, does not yet seem to be feasible
economically. Governments are focusing
on protecting good seed producing areas
and on monitoring spatfall rather than on
the establishment of hatcheries (FA0
1988).
Availability of suitable culture sites is
becoming a serious constraint in those
countries where mollusc culture is well
developed. Most of the suitable sites in the
two Koreas and Japan are already
occupied; even in peninsular Malaysia and
Thailand it is difficult to find new sites for
cockle (Anadaragranosa) culture. Overuse
of suitable sites carilead to the deterioration
of the culture environment. Growth rates
of oysters in Japan have been decreasing,
attributed to the self-pollution with the
excreta ofthe cultured animals themselves.
Similar problems are emerging in the
Republic of Korea, where the government
plans to limit further access to culture
sites (Park 1988). Mollusc culture in both
of these countries has been declining since
1987188.
Industrial pollution resultingin heavy
metal accumulation in cultured mussels,
is not yet a widespread problem in the
developing countries of the region. On the
other hand, bacterial contamination of
cultured molluscs originating from
pollution with domestic sewage is a
widespread public health concern in the
region. Such pollution of marine areas is
much less documented than that of the
freshwaters in the region, although the
situation in Southeast Asia is now under
increasing scrutiny (Ruddle 1981;
Alabaster 1986). Untreated sewage from
the burgeoning coastal population centers
is well known to contaminate otherwise
ideal mollusc culture sites. Moreover, with
the rapid development of tourism, hitherto
pristine sites are rapidly becoming polluted
with the untreated wastes of hotels and
beach resorts (Chua and Garces 1992).
Bacterial contamination is often reported
to occur also as a result ofpoor postharvest
handling of molluscs (FA0 1988).
Increasing occurrences of red tides are
further affecting culture sites in the region
(Maclean, this vol.).
Molluscs produced in the Asia-Pacific
region are in general low-priced. Supply
and demand are balanced and in recent
years production has decreased slightly in
Hong Kong, Japan, the Republic of Korea,
Malaysia, the Philippines, Singapore and
Thailand. The demand, however, would
increase if hygienic standards and the
general image ofthe product in this respect
were improved. Depuration, followed by
certification (already mandatory for some
export markets) is increasingly recognized
as an important means of boosting
consumption. Protecting production sites
from pollution and improving the hygiene
of postharvest handling seem to be more
viable options for the time being. Export
markets, however, cannot be developed
without the introduction of efficient