Conservation of Giant Clams – Part 3

Counting down, and it’s less than 10 days to the TED conference! 😀 For the third part of this series, let me shed light on the Laws & Legislations that exist to protect giant clam resources.

Part 3: Laws and Legislations

In general, we can review the state of knowledge in two categories: 1) the international components versus 2) the local components of the laws and legislations that surround giant clam resources. Each system of rules has its pros and cons, and we will take a look at each component:

The International Union for Conservation of Nature (IUCN)

Excerpts from Founded in 1948, IUCN has become the world’s oldest, largest and most diverse environmental network. It is also the global authority on the status of the natural world and the measures needed to safeguard it. IUCN comprises six commissions with experts dedicated to species survival, environmental law, protected areas, social and economic policy, ecosystem management, and education and communication.


Through the IUCN programme, the commission on species survival has been assessing the conservation status of species, subspecies, varieties, and even selected subpopulations on a global scale for the past 50 years. The IUCN Red List of Threatened Species was developed to provide taxonomic, conservation status, and distribution information on plants, fungi, and animals that have been globally evaluated using the IUCN Red List Categories and Criteria.

So how useful and effective is the IUCN Red List of Threatened Species? Essentially, it helps conservation workers to set conservation priorities, as well as to inform conservation efforts at both international and local scales. These are a set of recommended guidelines based on the IUCN Red List Categories and Criteria, the relevant documentation supporting the listing, and range map of species’s distribution. Numerous other considerations need to be accounted for when deciding which species should be actively (and/or legally) protected. These may include the extinction risk, ecological importance, phylogenetic importance, historical/cultural importance, economic feasibility, international agreements (CITES), and global population. The assessment data from the Red List can also be used to inform some of the international agreements such as Convention on Biodiversity (CBD) or CITES.

What is the situation for the giant clams then? Giant clams were highlighted in the early works of “The IUCN Invertebrate Red Data Book” by Wells et al. (1983). It described the various human pressures on giant clam populations, and how each species was threatened on a global scale. Since 1983, nine giant clam species (seven Tridacna spp. and two Hippopus spp.) have been formally re-assessed with the last update in 1996, and listed them as either ‘Least Concern’ or ‘Vulnerable’ (IUCN, 2017). Unfortunately, the present listings are not accurately reflecting contemporary trends, as well as the recent species (such as Tridacna noae, Tridacna squamosina, Tridacna lorenzi) (Neo et al., 2017). The major caveat here is that their status is in need of updating.

Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)

Excerpt from CITES is an international agreement between governments. Its aim is to ensure that international trade in specimens of wild animals and plants does not threaten their survival. The existence of such an agreement to ensure the sustainability of trade is important in order to safeguard these resources for the future. Because trade in wild animals and plants crosses the borders between countries, the effort to regulate it requires international cooperation to safeguard species from overexploitation.

CITES was drafted as a result of a resolution adopted in 1963 at a meeting of members of IUCN. It is an international agreement to which States (countries) adhere voluntarily. States that have ‘joined’ CITES are known as Parties, and CITES is legally binding to Parties. It does not take the place of national laws, but rather it provides a framework to be respected by each Party, which has to adopt its own domestic legislation to ensure CITES is implemented at the national level. 


So how useful and effective is CITES? CITES is fundamentally a framework (a set of concepts and guidelines) to help each Party of the Convention to develop their own regulations in managing the exploited resources. To assist Parties, there are the CITES Appendices I, II, III to the Convention that have listed species afforded at different levels or types of protection from over-exploitation (Appendix I being the most endangered, followed by Appendices II and III). Depending on the degree of protection the species needs, CITES work by subjecting international trade in specimens of selected species to certain controls. However, the effectiveness of enforcing CITES is largely dependent on whether the countries are Parties to the Convention, as well as the accuracy of trade data from Parties (Wells, 1997).

What is the situation for the giant clams then? In 1983, the first giant clam species to be listed on CITES Appendix II were Tridacna gigas and Tridacna derasa – the two largest clam species (Wells, 1997). Another five giant clam species were later listed in 1985, which regulated international trade in any of their body parts (shells, tissues, dead or alive). Appendix II consists of species that are not necessarily now threatened with extinction but that may become so unless trade is closely monitored. While there are inherent problems to the international trade of giant clams (see earlier), the scope of CITES does not include localised collection and trade within countries (i.e. domestic sale), regardless of their status as Party. Ongoing reports suggest that wild populations of giant clams are being over-collected for exports, instead of exporting cultured giant clams (Neo et al., 2017).

Country- and regional-specific regulations

Regional efforts to help manage giant clam fisheries have been few (e.g. South Pacific islands, Kinch & Teitelbaum, 2010), but much has been done locally to reduce exploitation. Here shows the summary of conservation efforts and regulations grouped in regions (Neo et al., 2017):

  • Red Sea, Southeast Africa, Indian Ocean — Generally lack specific laws or legislation to regulate recreational fishing of giant clams. Mauritius and India have own national laws to protect giant clams.
  • East Asia — Initiating efforts to restore impacted populations but mariculture there (except Japan) is still in its infancy. China, Japan, and Taiwan have own national laws to protect giant clams.
  • South China Sea — Unfortunately within disputed territorial waters, making ocean governance a challenge among numerous neighbours.
  • Southeast Asia — Has had a number of restocking efforts using mariculture, but the success of programmes has been variable at each site. Generally recognised that giant clams need protection, but only the Philippines, Malaysia, and Thailand have national legislations to regulate exploitation.
  • Australia, Pacific nations — Management of giant clam populations has been most committed and advanced, and shown to be effective. Australia has own national laws to protect giant clams.

Overall, the local enforcement measures vary in outcomes, and the success of it depends on the levels of exploitation (e.g. high versus low levels will influence period of recovery), local enforcement capacity, as well as community willingness to adopt practices. Unfortunately, illegal fishing remains widespread in many of these countries, most likely because of the traditional importance of giant clams as a coastal resource (either as a main food or back-up food), coupled with the lack of manpower and funding to support long-term monitoring and surveillance.


Well, all of these efforts have most definitely helped to raise awareness of the threats giant clam face, regulate trade, and prevent further declines of remaining populations. I would rate success levels as moderate, but we are getting there – step by step. There are both successes and failures (Teitelbaum & Friedman, 2008), and lessons can be learnt from each experience.

Unfortunately, one of the major challenges remains the need for long-term investment of manpower and funding. The need for strong local governance to implement fishery policies and to involve local communities to take up ownership of their own coastal resources can also help to strengthen the success of giant clam conservation programmes.

Not forgetting to complement all of these with the decades of giant clam research (see Parts 1 and 2), which has helped to reinforce the case for protecting these iconic bivalves. In my final part, I will share how we can combine science, communication, and policy to help save my favourite animal. 🙂

Reference List:

IUCN (2017) The IUCN Red List of Threatened Species. Accessed on 16-April-2017.

Kinch & Teitelbaum (2010) Proceedings of the regional workshop on the management of sustainable fisheries for giant clams (Tridacnidae) and CITES capacity building (4-7 August 2009, Nadi, Fiji). Secretariat of the Pacific Community headquarters, Noumea, New Caledonia.

Neo et al. (2017) Giant clams (Bivalvia: Cardiidae: Tridacninae): A comprehensive update of species and their distribution, current threats and conservation status. Oceanography and Marine Biology: An Annual Review, Volume 55 (July 2017). [Invited paper]

Teitelbaum & Friedman (2008) Successes and failures in reintroducing giant clams in the Indo-Pacific region. SPC Trochus Information Bulletin 14: 19-26.

Wells et al. (1983) The IUCN Invertebrate Red Data Book. IUCN, Gland, Switzerland and Cambridge, UK.

Wells (1997) Giant clams: Status, trade and mariculture, and the roles of CITES management. IUCN, Gland, Switzerland and Cambridge, UK.