Tridacna squamosa is widely distributed across the Indo-Pacific region. Reef surveys generally confirm the presence of this species throughout its geographic range, with signs of natural recruitment replenishing local stocks. In some locations, the distribution of this species is patchy, but the numbers appear to be moderately stable. There is no strong evidence to suggest a decline in the global population, but the species continues to face localised threats, including overharvesting in specific communities for local consumption or the aquarium trade. Given that it is associated with coral reefs, there is evidence of declining quality of habitats. Additionally, it is vulnerable to the impacts of ocean warming and acidification, which affects its symbiotic relationship with photosynthetic algae and its overall habitat stability. Ongoing monitoring is important to provide early warning of potential future declines.

The broad geographic distribution of this species may provide a resilience buffer against localised adverse events (e.g., climate variability), making it less vulnerable to extinction on a global scale. However, there are knowledge gaps in the genetic diversity and connectivity of distinct populations throughout the known range. It is therefore essential to maintain genetic diversity and also to prevent the loss of unique genetic traits that could enhance the species’ resilience to environmental changes and anthropogenic impacts. CITES provides ongoing protection for this species.

While the mariculture knowledge on this species is well-established and successful in raising cultured individuals, restocking efforts are not well understood or underreported (i.e., it is unclear whether efforts have led to an increase in stock numbers). In addition, breeding programmes typically use a limited number of genetic populations. This narrow genetic basis could reduce the species’ resilience to environmental changes and diseases in the future. Therefore, the population may decline in the future as the causes of reduction may not have ceased. The recent availability of the other Tridacna genomes also opens up new avenues for studying its population genetics, emphasising the importance of conserving genetically diverse populations.

On the basis of the moderately stable population size with adequate measures to implement conservation strategies when needed, this species is assessed as Least Concern.

Tridacna squamosa is present from the Red Sea and eastern Africa in the west to the Pitcairn Islands, Ryukyus (southern Japan), and Queensland (Australia) in the east (Neo et al. 2017). Globally, it is the second most widespread giant clam species. New records for the central Pacific (Australes, Tuamotu, and Gambier Archipelago) have been added, although some gaps persist (e.g., the species remains undetected from the Society Islands in the French Polynesia) (Gilbert et al. 2007, Andréfouët et al. 2014). It is possibly extinct in the Cocos (Keeling) Islands, Niue (Neo et al. 2017), and Northern Mariana Islands (J.W. Fatherree pers. comm. 2024).

Throughout its geographic distribution, T. squamosa is widely present with varying abundances (Cui et al. 2019, Rehm et al. 2021, Dolorosa et al. 2024). In some areas, it is considered an abundant and common giant clam species (Yusuf et al. 2009, Neo and Todd 2013, Rehm et al. 2021). Although it is a relatively common species, an increasing number of studies are reporting declines or rarity in populations compared to past numbers (e.g., Neo et al. 2019, Bavoh et al. 2021, Mehrotra et al. 2021, Dolorosa et al. 2024). As reviewed by Neo et al. (2017), the lowest density reported was 0.2 individuals per hectare at Helen Reef, Western Caroline Islands, Palau (Hester and Jones 1974), while the highest density reported was 10,000 individuals per hectare at Chiriyatapu, Andaman and Nicobar Island, India (Ramadoss 1983). So far, this species has been reported as locally extinct in the Cocos (Keeling) Islands, Niue, and the Northern Mariana Islands (Neo et al. 2017), suggesting that the global population (and subpopulations) have been moderately stable over the decades.

Like other giant clam species such as Tridacna crocea and Tridacna maxima, this species exhibits high genetic connectivity within regional waters, but shows limited genetic exchange across larger geographic areas. In another recent study by Fauvelot et al. (2020), the COI+16S phylogeny revealed that this species comprised five sub-clades: one from the Red Sea, one from the Western Indian Ocean and two from the Western Pacific Ocean. As a species that reproduces by spawning, it relies on surface ocean currents to disperse its pelagic larvae. However, this dependency on specific current patterns also implies that the risk of local extinction could be elevated, particularly if these currents shift or if barriers to larval dispersal arise.

The mariculture knowledge on this species is well-established and successful in raising cultured individuals (Latama 1995, Adulyanukosol 1997, Neo et al. 2011). There have been numerous attempts to translocate cultured clams for enhancement programmes (e.g., restocking purposes in Indonesia, Malaysia, Philippines, Singapore, Thailand, Fiji, Palau, Federated States of Micronesia, Marshall Islands, Tonga, Vanuatu, and Solomon Islands) (Neo et al. 2017). However, the outcomes of translocating these cultured clams for conservation are not well understood or underreported (i.e., it is unclear whether efforts have led to an increase in stock numbers).

Tridacna squamosa inhabits a wide depth range, from reef flats to reef slopes down to 42 m (Jantzen et al. 2008), and is usually found in sheltered sites (e.g., wedged between corals) (Rosewater 1965). Juvenile individuals are typically byssally attached to coral rubble, while adults may be byssally attached or free-living. This species typically attains shell lengths of ~40 cm, but there have records of larger specimens including three individuals between 48 and 52 cm from Maldives (Basker 1991) and an individual at 47.6 cm from Tonga (Huber and Eschner 2011).

All species of giant clams are known to be simultaneous hermaphrodites. The reproductive periodicity of T. squamosa has been examined in some locations (Philippines: Solis 1987; Malaysia: Tan and Yasin 2000, 2001; Singapore: Neo et al. 2011). These studies indicated that the spawning of this species coincided with the wet season and high seawater temperatures. According to Mingoa-Licuanan and Gomez (2007), this species exhibit male maturity at 18 cm and female maturity at 19 cm, but no age was provided.

Through mariculture (Nugranad et al. 1997, Niartiningsih et al. 2020), there is a good understanding of T. squamosa’s reproduction potential. There is also good mariculture interest in this species, and it is often used as a model organism in ecological studies and sometimes in the aquarium trade (Mies et al. 2017, Militz and Southgate 2021, Vogel and Hoeksema 2024). Most of the ecological studies focused on investigating the growth and survival of juvenile clams (Foyle et al. 1997, Charuchinda and Asawangkune 2000, Calumpong et al. 2003, Ow Yong et al. 2022), as well as their behaviour (Huang et al. 2007, Neo et al. 2009, Sim et al. 2018).

The presence of T. squamosa can produce beneficial outcomes for coral reef ecosystems. For instance, the net primary productivity of this species (18.14 g O₂ m^-2 d^-1) is greater than that of many other coral reef primary producers including macroalgae, crustose coralline algae, and hard corals (Neo et al. 2015). Vicentuan-Cabaitan et al. (2014) also identified an entire epibiont community living on the shell valves of this species in Singapore, highlighting that these giant clam shells provide much more surface area for colonisation compared to the patch of substrate they occupy. Furthermore, T. squamosa is a known host of the cyclopoid copepod species (Anthessius alatus, Anthessius amicalis, Anthessius solidus, Lichomolgus tridacnae and Paclabius tumidus), pea crabs (Tridacnatheres whitei and Xanthasia murigera), and pontoniinid shrimps (Anchistus australis, Anchistus demani, Anchistus miersi and Conchodytes tridacnae) (Neo et al. 2015).

The extent of fishing of T. squamosa can vary depending on the local coastal communities. For instance, this species (with other large clam species) is opportunistically taken during fishing trips targeting other marine resources such as fish and lobsters (Purcell et al. 2020). On the other hand, in the Republic of Kiribati, all giant clams (including T. squamosa) are heavily exploited for subsistence purposes (Eurich et al. 2023). Large scale harvesting is now limited by protection from CITES.

Climate change could threaten this species. There were some reports of bleaching incidences during past global bleaching events (Junchompoo et al. 2010, Mies et al. 2019). Elevated temperatures were also found to be detrimental to the photosynthetic performance of juveniles (Elfwing et al. 2001) and to impact the development and survival of veligers (Eckman et al. 2019). Furthermore, experiments combining the effects of elevated temperatures and high pCO₂ levels revealed strong synergistic effects that significantly reduced the survival and growth of juveniles (Watson et al. 2012, Syazili et al. 2020). Notably, ocean acidification alone has sublethal effects on this species, with individuals exhibiting reduced shell growth rates (i.e., lower calcification rates) (Watson 2015, Li et al. 2022).

Other threats mentioned include anthropogenic influences such as coastal development and habitat loss (Neo and Todd 2012). Notably, there have been several studies examining the effects of varying light levels or irradiance on the photosymbiosis process in T. squamosa. Under lower light conditions (i.e., increased sediment output), the photosynthetic performance appeared to be reduced (Blidberg et al. 1999, Tedengren et al. 2000). These studies suggest that the maximum depth distribution of this species could be largely restricted by reduced light availability in areas with higher levels of sediment input.

Tridacna squamosa is typically a species exploited at the domestic level for local consumption. In Sabah-Malaysia, giant clams (including T. squamosa and T. maxima) are regularly consumed as traditional food cuisines (Abd-Ebrah and Peters 2021, 2022). Elsewhere, T. squamosa (lumped together with other giant clams) continues to be harvested for subsistence purposes to varying extents (i.e., opportunistic to intensive harvesting) across its range (Purcell et al. 2020, Eurich et al. 2023).

In the 1990s, the shells of this species were used in various forms in the ornamental shell trade. In the Philippines, these shells were most widely used either as specimens, ornamental shells or materials for various shell crafts (e.g., ashtrays, lamps, vases, choker beads) (Juinio et al. 1987). The most marketable size range for this species is 5–15 cm (Juinio et al. 1987). In Palau, the then Micronesian Mariculture Demonstration Center (MMDC, now known as PMDC) sold T. squamosa shells as ornaments (Heslinga 1996). They were extremely popular and three sizes were sold: 5-cm shells for USD$3, 10-cm shells for USD$5, and 12–14-cm shells for USD$8.

Another specific use/trade of shells of this species is the floor-tile industry. These shells (lumped together with other giant clams) were previously collected for the highly popular floor-tile industry in Central Java, Jakarta, and East Java (Firdausy and Tisdell 1992). Approximately every two weeks, about 10–20 tonnes of processed clam shells were sought for the floor-tile industry in Jakarta. This species was listed as one of the species sold in the market.

This species is also marketed in the live aquarium trade (Mies et al. 2017, Vogel and Hoeksema 2024) and is possibly used for restocking (Militz and Southgate 2021).

All giant clams (subfamily Tridacninae) are listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) on the basis of so-called 'look-alike species', i.e., species whose specimens in trade look like those of species listed for conservation reasons (Wells 1997). Thus, CITES regulates the international trade in any of their parts (shells, tissues, alive or dead).

In situ protection of stocks: T. squamosa has legal protection under the respective wildlife and fisheries laws in the following countries: Australia, China, Taiwan, Japan (Okinawa), India, Indonesia, Malaysia, Myanmar, Philippines, Singapore, Thailand, Viet Nam, South-east African countries (including Somalia, Comoros, Kenya, Madagascar, Mauritius, Mayotte, Mozambique, Seychelles, South Africa, Tanzania), New Caledonia, Solomon Islands, and Pitcairn Islands. In contrast, the South Pacific nations (such as Papua New Guinea, FSM, Palau, Marshall Islands, Samoa, Tokelau, Tonga, and Vanuatu) protect their wild stocks by introducing restrictions on harvesting wild giant clams (such as using size, weight or bag limits, gear restrictions or permits) or introducing restrictions on individual uses, including recreational, tourism, and aquaculture. The levels of enforcement of laws, however, are unclear and underreported.

Stock enhancement through mariculture: During the 1980s, the efforts to re-establish or supplement depleted populations of giant clams (including this species) were mainly funded by the Australian Centre for International Agricultural Research (ACIAR) (Davila et al. 2017). The focus of the programme was to breed and release hatchery-reared giant clams back to the wild, at local and regional scales. This species has been successfully cultured, mainly for restocking purposes in Indonesia, Malaysia, Philippines, Singapore, Thailand, Fiji, Palau, Federated States of Micronesia, Marshall Islands, Tonga, Vanuatu, and Solomon Islands, but there have been no reports of the outcomes of these endeavours (Neo et al. 2017). Individuals were also translocated from Palau to Guam and Tokelau, and Fiji to Samoa to help with local restocking initiatives (Kinch and Teitelbaum 2009). Juveniles from culture efforts in Australia, Palau, Federated States of Micronesia, Marshall Islands, Tonga, Vanuatu and Solomon Islands are (or have been) exported for the aquarium trade. As part of its larger research programme, the Darwin Aquaculture Centre (Northern Territory, Australia) also cultures this species to encourage farming as an economic opportunity for indigenous communities (Darwin Aquaculture Centre pers. comm. 2016).

Wildlife trade: The trade numbers of T. squamosa are made up of both wild-sourced clams from primarily Viet Nam and Cambodia and cultured clams from Marshall Islands, Tonga, Indonesia, and Palau (Vogel and Hoeksema 2024). Based on the CITES Trade Database, Indonesia, Marshall Islands, and Palau were some of the major exporting countries for cultured T. squamosa between 2011 and 2019 (Vogel and Hoeksema 2024). Notably, the trade numbers for this species were lower in recent years (2011–2019) compared to 2001–2010, suggesting a dip in the demand for the species. Between 2001 and 2019, the import-export of live T. squamosa was far greater than that of shells (Vogel and Hoeksema 2024). In general, it appears that several cultivation programmes are focused on growing giant clams for the global marine aquarium trade (Mies et al. 2017, Militz and Southgate 2021).

This species has been assessed as a proposed threatened species in a status review for the US Endangered Species Act, also on the basis of being a look-alike species to other protected species (NOAA 2024).