2012. Review of Significant Trade - Cites

Tridacna spp.
Management: The export and trade of wild-sourced specimens was reported to be banned
in the Solomon Islands (Solomon Islands Consolidated Legislation, 1996), however the trade
and export of farmed specimens was allowed (Solomon Islands, 2009). The lack of
regulations on subsistence harvesting was considered to be a particular threat to T. derasa
(Green et al., 2006). Traditional local management practices were reported to be in place in
some areas (Kinch et al., 2006). Further details are provided in the genus overview.
The Solomon Islands Ministry of Fisheries and Marine Resources (2009) reported that
Tridacnidae farming in the country focuses on T. derasa, due to its fast growth and
durability. T. derasa was considered to be well suited for meat production due to its good
survival and high meat gain (SPC Aquaculture Portal, 2009). Hean and Cacho (2003)
considered it to be the species of Tridacnidae with the best potential for mariculture
production as seafood. The species was also considered to show good potential for the
production of aquarium specimens, and possibly adductor muscle, on village farms
(Hart et al., 1998). In large-scale grow-out trials conducted in 11 village farms in the Solomon
Islands, T. derasa was found to attain a mean shell length of 15 cm (±1.98 s.d.) in a grow-out
of 24 months, with a 92.2 per cent (±9.1 s.d.) survival rate (Hart et al., 1998). The results
indicated that grow-out time needed to produce individuals of optimum size for the
aquarium market was only 7 months (Hart et al., 1998).
Since the establishment of small-scale farming programmes for rural communities by the
WorldFish Center during the 1990s, hatchery-reared juvenile T. derasa was reported to
continue to be supplied to farmers in the Western Province who then tended the clams
during the grow-out stage (Horokou et al., 2010). After grow-out in the villages, these
specimens were sold to the company Aquarium Arts, which exported specimens for the
global marine aquarium trade (Horokou et al., 2010). In 2007, Solomon Islands was reported
to have produced 4300 individuals of cultured T. derasa for the aquarium trade, with an
estimated national export potential of 15 000 cultured individuals (Kinch and
Teitelbaum, 2010).
T. derasa was previously selected for the Review of Significant Trade at the 20 th meeting of
the Animals Committee in 2004 (AC20 Summary Record), and although Solomon Islands
was not one of the countries selected for review, it was noted that the significant trade from
Solomon Islands “continues to be of concern”, and that as the trade of wild-sourced
specimens had been reported by importers, the nature of all specimens in trade should be
verified (IUCN, 2006b).
Tridacna gigas (Linnaeus, 1758): Solomon Islands.
Biology: The largest Tridacnidae species Tridacna gigas commonly grows up to 80 cm in
length (Kinch and Teitelbaum, 2010) although it can grow to a maximum shell length of
137 cm (Kinch, 2002) and weight of 260 kg (Oliver, 1975). The species was reported to reach
sexual maturity as a male at about 37 cm shell length, and as a hermaphrodite at the age of
9-10 years (Raymakers et al., 2003). Munro (1993) reported that an individual of 70-80 cm
shell length was capable of producing up to 240 million eggs.
T. gigas was reported to be the fastest growing Tridacnidae species (Pernetta, 1987), with
mean growth rates of 4.1 mm per month measured in wire mesh cages in shallow, subtidal
coral reefs in the Solomon Islands (Bell et al., 1997). Munro (1983) reported that it may reach
50 cm length and 6 kg flesh weight in 5-7.5 years.
Preferred habitats were reported to include sandy bottoms or coral rubble on shallow
lagoons and coral reef flats (Tervo and Csomos, 2001).
Distribution in range State: T. gigas was reported to be widespread, occurring from the
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