Tridacna crocea is primarily distributed in the Central Indo-Pacific region. Reef surveys generally confirm the abundance of this species throughout its geographic range, as well as strong signs of natural recruitment replenishing local stocks. In some regions, 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 global population (i.e., few incidences of local extinctions), but the species continues to face localised threats including overharvesting in specific communities for local consumption or 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 climate change (i.e., ocean warming and acidification), which affects its symbiotic relationship with photosynthetic algae and its overall habitat stability.

While the mariculture knowledge on this species is well-established and successful in raising cultured individuals, there have been limited efforts in translocating or restocking the cultured clams for conservation, or these efforts are not well understood or are 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.

CITES provides ongoing protection for this species. Giant clams are vulnerable to climate change, as rising temperatures can cause bleaching of their photosymbionts. Ongoing monitoring is important to provide early warning of potential future declines.

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

This species has a wide distribution. It can be found from Australia to Japan, east to Palau, and from Vanuatu to the Andaman Islands (Neo et al. 2017) and west to the Indian Ocean (J.J. ter Poorten pers. comm. 2024). It is possibly extinct in the Northern Mariana Islands (Wells 1997).

This species is still reasonably abundant in many areas throughout its geographic distribution (Cui et al. 2019, Dolorosa et al. 2024) owing to its small body size and the difficulty of removing individuals from reef substrata (i.e., it is less favoured for harvesting). In some areas, it is the most abundant and common giant clam species (Yusuf et al. 2009, Neo et al. 2019, Bavoh et al. 2021, Rehm et al. 2021, Iskandar et al. 2023). Despite its abundance, an increasing number of studies are reporting declines in populations compared to past numbers (e.g., Santiago and Ablan-Lagman 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 Mare, New Caledonia (Dumas et al. 2011), while the highest density reported was 250,000 individuals per hectare at Cau Island, Con Dao Archipelago, Viet Nam (Selin and Latypov 2011). So far, this species is locally extinct only in the Northern Mariana Islands (Neo et al. 2017), suggesting that the global population (and subpopulations) have been moderately stable over the decades.

Genetic analyses revealed three distinct clades of this species: one in western Sumatra, another spanning central Indonesia, and a third confined to eastern Indonesia and Papua. The species shows a restricted gene flow within and among these regions. The observed average dispersal distances are only 25–50 km, which is considerably less than the predicted passive dispersal distances of 406–708 km based on 10-day surface current models. These limited gene flow patterns may increase their local extinction risk (Hui et al. 2016).

The mariculture knowledge on this species is well-established and successful in raising cultured individuals, and there have been some attempts to translocate cultured clams for enhancement programmes (e.g., Tonga, Okinawa-southern Japan) (Teitelbaum and Friedman 2008, Neo et al. 2017). However, the outcomes of translocating these cultured clams for conservation are poorly understood or underreported (i.e., it is unclear whether efforts have led to an increase in stock numbers).

This species mostly inhabits the reef flats in shallow waters at a depth of no more than 10 m (Hamner and Jones 1976, Hamner 1978); but may also occur in deeper waters of around 20 m (J.J. ter Poorten pers. comm. 2024). This species is a rock borer that embeds its entire shell and body into the substratum, leaving only the mantle exposed (Yonge 1936). In the Ryukyu Islands, Iwai et al. (2006) noted that individuals bore into limestone substrata near the shore, on reef flats or dead parts of massive coral colonies. The species appears to also be well-adapted to low salinity levels, often being found in areas that experience freshwater runoff (Hart et al. 1998).

All species of giant clams are known to be simultaneous hermaphrodites. The reproductive periodicity of this species has been examined in some locations. In Orpheus Island (Australia), it has a restricted window for spawning (between October and November) (Shelley and Southgate 1988). On the other hand, the spawning seasons of this species are from June to August in Okinawa, which coincides with the summer months (Murakoshi and Kawaguti 1986a). According to Mingoa-Licuanan and Gomez (2007), this species exhibits male maturity at 5 cm and female maturity at 7 cm. Murakoshi and Kawaguti (1986b) also found that individuals below 5 cm are male-phase mature, but the state of simultaneous hermaphroditism becomes prominent beyond 5 cm. For both studies, the age of specimens was not provided.

Through mariculture (Jameson 1976, Murakoshi 1978, 1986, Hean and Cacho 2002, 2003), there is a good understanding of this species’ reproduction potential. The mariculture interest is relatively high because it is popular in the aquarium trade (Mies et al. 2017, Militz and Southgate 2021, Vogel and Hoeksema 2024). Numerous ecological studies on the larvae metamorphosis (Kawaguti 1983), symbiosis (Ishikura et al. 1999), ecology, and behaviour (Suzuki 1998) of T. crocea were published by Japanese researchers. The latter can be attributed to the reliance on this species for domestic consumption, which is also part of the traditional culture (Claus 2017).

There is some evidence to demonstrate that the presence of this species can produce beneficial outcomes for coral reef ecosystems. For instance, a natural population of this species ranging between 955–2,441 individuals per hectare is capable of filtering over 2,115–8,144 L h-1 (Neo et al. 2015). Similar to T. maxima, another unique ecological role is bioerosion as T. crocea is capable of eroding rubble that can result in a localised scale of reef attrition (Neo et al. 2015). Furthermore, this species is a known hosts of the pea crab (Xanthasia murigera) and pontoniinid shrimps (Anchistus demani, Anchistus miersi and Conchodytes tridacnae) (Neo et al. 2015).

The extent of fishing of T. crocea can vary depending on the local coastal communities. For instance, as the species is considered widespread and abundant, it is preferentially collected for local consumption in Okinawa, Japan (Iwai et al. 2006), the Solomon Islands (Ramohia 2006), and Tioman Island, Malaysia (A. Chelliah pers. comm. 2023). On the other hand, it is less popular elsewhere given its small body size and the difficulty of extracting from the reef substrata (Neo et al. 2017, Purcell et al. 2020). As this species is highly popular in the aquarium trade, numerous South Pacific nations (such as Fiji, Solomon Islands, Vanuatu, and the Federated States of Micronesia) were extracting their wild T. crocea for live exports in the aquarium trade in the early 1990s and 2000s, which appeared to have impacted their populations (Neo et al. 2017).

Climate change could threaten this species. Experimental studies examining the impacts of thermal stress on this species have revealed that the density of endosymbiotic Symbiodiniaceae decreases significantly and the higher temperatures induce oxidative stress that causes the collapse of the symbiosis between the host and endosymbionts (Zhou et al. 2019, Ma et al. 2021). In another study, this species heated at 32–33°C for 16 days with a recovery period showed lower phototrophic performances (Fv/Fm and photosynthesis), and their reproductive potential was significantly affected (i.e., lower gonadosomatic index and higher proportion of regressive eggs that are no longer viable) compared to control giant clams (Sayco et al. 2024). Furthermore, under high pCO2 conditions, this species’ juveniles revealed negative shell growth and the productivity of endosymbionts did not increase, suggesting that this species will be negatively impacted by ocean acidification (Kurihara and Shikota 2018, Ma et al. 2021).

Notably, pathogens and diseases are more commonly reported in this species, probably due to its popularity in the aquarium trade. Perkinsus sp. (protozoan) was reported to cause tissue weight loss (Goggin 1996) and high mortality (Reavill et al. 2009). Another paper reported parasitism by an unnamed protozoan in the hemolymph of this species, but the impacts on species are not known yet (Nakayama et al. 1998). Fungal infection was also reported for this species, where fungi in the soft tissues caused the presence of stunted zooxanthellae, suggesting that the animals were stressed and probably malnourished (Norton et al. 1994). A single report of trematode infection in this species from the Great Barrier Reef found that while parasitism by trematode was low, the affected individuals caused heavy castration on the host clams, where gonadal tissues are completely replaced by sporocysts (Shelley et al. 1988).

This species is typically exploited at the domestic level for local consumption. For Pacific Island communities, the role of giant clam meat in providing high-quality protein was significant, as analysis showed that raw tridacnine meat (Hippopus hippopus and Tridacna crocea) contains high content of vitamin A, which is generally absent from the meat of other molluscs and some fish species (Hviding 1993). In Okinawa, Japan, this species is often used in local cuisines as part of their traditional culture (Okada 1997, Claus 2017). In the Solomon Islands, where the species is considered widespread (Wells 1997), it is preferentially harvested by the locals as a source of food (Hviding 1993). Recent surveys (Ramohia 2006) noted that the species is much less common than it used to be in the Solomon Islands. In some Southeast Asian communities, they believe consuming giant clams (including T. crocea) helps mothers breastfeed their newborns (Abd-Ebrah and Peters 2020). Elsewhere, this species (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 (Harahap et al. 2018, Rehm et al. 2021).

In the 1990s, this species’ shells were used in various forms in the ornamental shell trade. In the Philippines, the shells had the lowest market demand and were sold cheaply (Juinio et al. 1987). In Palau, the then Micronesian Mariculture Demonstration Center (MMDC, now known as PMDC) sold this species’ shells as earrings, pins or shell crafts (Heslinga 1996).

Cultivated T. crocea is primarily marketed in the live aquarium trade (Mies et al. 2017, Vogel and Hoeksema 2024), but has a limited use for restocking (Neo et al. 2017). While most of the individuals sold for aquarium trade appear to be cultured, the export of species from Viet Nam is mainly of wild stock origin (Mies et al. 2017). In the latter case, the local government in Viet Nam tightened the regulations around sourcing wild specimens for sale, which led to the possible re-routing of wild-caught clams through Cambodia for export (i.e., where restrictions may be less strictly implemented) (Neo et al. 2017). The vast majority of giant clams exported to Western countries are for international trade, which is almost entirely the aquarium industry (Mies et al. 2017). Elsewhere, such as in Okinawa, cultivated T. crocea are grown and sold for local consumption (Neo et al. 2019).

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: This species 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, New Caledonia, and the Solomon Islands. In contrast, the South Pacific nations (such as Papua New Guinea, Palau, 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 are underreported.

Stock enhancement through mariculture: As this species is thought to be common and widespread throughout its geographic range, there have been limited efforts to restock and enhance its stocks. However, there is evidence of intensive collection of wild clams for exporting in the aquarium trade (Neo et al. 2017, Vogel and Hoeksema 2024). Currently, only the Okinawa Prefecture has fully operational hatcheries to supply juvenile spats for restocking the reefs around the Ryukyu Archipelago (Teitelbaum and Friedman 2008). Because of its comparatively slow growth and poor early survival rates, it is often regarded as less suitable (not cost-effective) for aquaculture or mariculture operations. Should the species require enhancement programmes elsewhere, the mariculture techniques are well-established.

Wildlife trade: Since the 1980s, the giant clam species with the most colourful mantles, T. maxima and this species, have been the most popular in the aquarium trade (Mies et al. 2017, Vogel and Hoeksema 2024). The trade numbers of T. crocea are made up of both wild-sourced clams from primarily Viet Nam and Cambodia and cultured clams from Viet Nam and Palau (Vogel and Hoeksema 2024). Based on the CITES Trade Database, Palau, Indonesia, and Micronesia were some of the major exporting countries for cultured individuals of this species 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 clams of this species was far greater than 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).