The global trade in marine ornamental species

From ocean to aquarium
The nine giant clams (tridacnids) common in trade
❏ Tridacna maxima: the rugose or small giant clam is the
most wide-ranging of all giant clam species, being found
from the east coast of Africa, through the Indian Ocean and
across the Pacific to Polynesia and Pitcairn 83 . It is still
relatively abundant throughout its range although its status
in the Indian Ocean is poorly known. It has a distinct brightly
coloured mantle (blue, green and brown), which makes it
particularly attractive for the aquarium trade. GMAD data
show a total of 15,172 specimens as exported from Viet Nam,
Fiji, the Solomon Islands, Tonga, Vanuatu, the United States
and unknown countries between 1991 and 2001 (importers’
data) (or a total of 8,215 from Fiji and the Solomon Islands
between 2000 and 2001 based on exporters’ data).
❏ T. squamosa: the fluted or scaly giant clam has a generally
speckled mantle in blue, brown and green. Like T. maxima, it
is fairly abundant throughout its range although little is
known of its status in the Indian Ocean. GMAD data show a
total of 6,711 T. squamosa as exported from Fiji, Indonesia,
the Solomon Islands, Vanuatu, Viet Nam and unknown source
countries between 1991 and 2001 (importers’ data) (or a total
of 2,339 from Fiji, Indonesia and the Solomon Islands
between 1999 and 2001 based on exporters’ data).
❏ T. crocea: the crocus or boring giant clam, although
smaller, is similar to T. maxima in that it has a brightly
coloured mantle. It is assumed to be generally widespread
throughout its distribution area, from the west coast of the
Malaysian peninsula, the South China Sea, the Coral Sea,
southern Japan to southern Australia, to Micronesia and east
to Palau 83 . Like T. maxima it is a popular species in the
aquarium trade. GMAD data show a total of 11,685 T. crocea
as exported from the Solomon Islands, Vanuatu, Viet Nam
and unknown source countries between 1991 and 2001
(importers’ data) (or a total of 17,881 from Fiji, Indonesia and
the Solomon Islands between 2000 and 2001 based on
exporters’ data).
❏ T. gigas: is considered to be the true giant clam as it can
reach dimensions of more than 1.4 m in shell length. The
mantle is brown-green with blue or green spots. This species
is particularly sought after for food. It has suffered extensive
reductions throughout its range due to overexploitation and
is extinct in Fiji, Guam, New Caledonia, most areas of the
Philippines and the Northern Marianas. Population levels
have been dangerously reduced in most of Japan, Taiwan,
Tuvalu, the Federated States of Micronesia and Vanuatu.
GMAD data show a total of 1,808 T. gigas as exported from the
Solomon Islands, Vanuatu and unknown source countries
between 1991 and 2000 (importers’ data) (or a total of 149
from Palau, Indonesia and the Solomon Islands between
2000 and 2001 based on exporters’ data).
❏ T. derasa: the smooth or southern giant clam is the second
largest species with its shell reaching lengths of up to 60 cm.
Its mantle has elongate brown, green and blue patterns. It is
known to be fairly abundant in Palau, northern Papua New
Guinea, Australia, the Solomon Islands, New Caledonia, Fiji
and Tonga. Although it has been reintroduced in a number
of locations outside its natural range, wild stocks have
only become established in Yap. GMAD data show a total
of 24,960 T. derasa exported from the Solomon Islands,
Vanuatu and unknown source countries between 1988 and
2001 (importers’ data) (or a total of 8,937 from Fiji, Palau,
Indonesia and the Solomon Islands between 2000 and 2001
based on exporters’ data).
❏ T. tevoroa: the deep water devil clam is a rare species that
only lives at depths greater than 20 m in the northern Tonga
Islands and eastern Fiji Islands. No data in GMAD.
❏ T. rosewateri: is a newly described species similar to T.
squamosa. It has a very restricted range, only occurring on
the Saya de Malha Bank, Mauritius, in the Indian Ocean. No
data in GMAD.
❏ Hippopus hippopus: the bear paw, horse’s hoof or
strawberry giant clam has a heavy and thick shell with a dull
yellow-brown mantle. Its distributional range is similar to
that of T. crocea but population numbers are lower and local
extinctions have occurred. GMAD data show a total of 58 H.
hippopus as exported from the Solomon Islands and
unknown source countries between 1999 and 2000
(importers’ data) (or a total of 551 from Palau and the
Solomon Islands between 2000 and 2001 based on
exporters’ data).
❏ H. porcellanus: the china clam, has a very limited range
in the region of Indonesia, the Philippines and Palau. Its
appearance is similar to that of H. hippopus. No data in
GMAD.
Source: Wells 80 , Ellis 81 , Raymakers et al 82 and data from GMAD.
30