The IUCN Red List categorizes species into nine groups (Table 2), which Reference [100] defined based on population size, rate of decline, geographic distribution area, fragmentation distribution, and population degree. The importance of applying any measures without extensive information, including suspicion and potential future threats, is emphasized “so long as these can reasonably be supported” [19]. The “Threatened” category includes “Critically Endangered”, “Endangered”, and “Vulnerable” [21] on its Red List.

Table 3 shows that Malaysia has 24 turtle species, four of which are sea turtles, and the other 20 are freshwater turtles (two of which are introduced species) [14,101]. According to the IUCN Red List, a sea turtle (Eretmochelys imbricata) and six freshwater turtle populations (Manouria emys, Batagur affinis, Orlitia borneensis, Batagur borneoensis, Indotestudo elongata, and Chitra chitra) are critically endangered in Malaysia (Figure 2). In contrast, a sea turtle (Chelonia mydas) and five freshwater turtles (Heosemys annandalii, Cuora amboinensis, Heosemys spinosa, Chitra indica, and Pelochelys cantorii) were endangered in Malaysia. Two sea turtles (Dermochelys coriacea and Lepidochelys olivacea) and six freshwater turtles were vulnerable (Malayemys macrocephala, Notochelys platynotan, Siebenrockiella crassicollis, Amyda cartilaginea, Manouria iimpressa, and Pelodiscus sinensis). However, two sea turtles were reported by Reference [102] in The ASEAN Post; a source from the World Wildlife Foundation (WWF) Malaysia shows that the Leatherback turtle is critically endangered, and the Olive Ridley turtle is endangered in the Malaysian ocean. Moreover, one species, Cyclemys dentata, is near threatened, and two species, Dogania subplana and Trachemys scoundaripta, are less concerned.

All the turtle species are distributed all over Malaysia. However, Terengganu is home to 17 species, including four species of sea turtles (Chelonia mydas, Dermochelys coriacea, Lepidochelys olivacea, and Eretmochelys imbricata) and 13 species of freshwater turtles (Trachemys scripta, Batagur affinis, Batagur borneonsis, Coura amboinensis, Siebenrockiella crassicollis, Manouria emys, Amyda cartilaginea, Dogania subplana, and Pelochelys cantorii) [14]. In addition, referring to Figure 3, the IUCN Red List analysis shows that 29 percent of Malaysia’s turtle species are critically endangered and 25 percent are endangered.

The Convention’s Appendices I, II, and III are lists of species with different levels of protection from over-exploitation [123]. Appendix I lists the most endangered plants and animals on the CITES list. They are almost extinct, but CITES allows international trade in specimens of these species as long as the import is not for commercial use (i.e., a scientific research study) [124].

In Appendix II, there is a list of species that are not threatened with extinction right now, but if the trade is not controlled, there is a high chance that they will be in the future. It also includes supposed “similar species”, such as species whose standards in exchange resemble species recorded for conservation purposes. Trade-in specimens of Appendix-II species may be authorized by issuing an export permit or re-export permit certificate. No import permit is necessary for these species under CITES (although a permit is needed in some countries with stricter measures than CITES requires) [125].

Appendix III contains a list of species added at the request of a party that already regulates international trade in the species. Specimens of the species in this appendix can be traded around the world only if the proper permits or certificates are shown [123].

An analysis of Figure 4 reveals that CITES has classified Malaysian turtles as 67 percent threatened, including Manouria emys, Orlitia borneensis, Batagur borneoensis, Indotestudo elongate, Heosemys annandalii, Cuora amboinensis, Heosemys spinosa, Chitra indica, Pelochelys cantorii, Malayemys macrocephala, Notochelys platynotan, Siebenrockiella crassicollis, Amyda cartilaginea, Manouria impressa, Cyclemys dentata, and Dogania subplana. About 25% (Batagur affinis, Chitra chitra, Eretmochelys imbricata, Chelonia mydas, Dermochelys coriacea, and Lepidochelys olivacea) are the most endangered species.

The [21] population trends for all VU, EN, and CR turtle populations are decreasing. In conclusion, many factors contribute to threats. This entry compiles and documents the work of other Malaysian researchers and decision-makers for future reference (Figure 5). The primary causes of concern are egg consumption and trade [4,126]. The main threats to turtles are illegal and unregulated turtle poaching by Hainan (China) vessels and Vietnam [1]. Turtles are hunted for food, medicine, and ornaments [127]. In Malaysia, religious beliefs have reduced the killing of adult turtles for food [128]. On the other hand, building dams, taking turtle eggs, removing riparian vegetation, sand mining, and drowning in fishing nets are some of the turtle’s most significant problems [129,130,131,132,133].

According to References [134,135], the most critically endangered turtle species may become the most sought after due to their scarcity, which makes them especially valuable in the pet trade, hunting, and habitat degradation. Reference [136] reports that they are eaten, collected, butchered, and traded in large numbers; they are used for pets, food, and traditional medicine—eggs, juveniles, adults, and body parts are all exploited indiscriminately, with no regard for sustainability [137]. Their habitats are being destroyed, developed, fragmented, and polluted at an alarming rate [138,139]. Species all over the world are threatened or vulnerable, with many critically endangered. Others are on the verge of extinction, and a few have already perished [140]. Humans are threatening the extinction of countless eons and turtles [141].

Aside from overt and highly impactful conservation threats such as overexploitation and habitat destruction, the global turtle fauna is also increasingly facing another insidious threat: genetic pollution caused by human-facilitated hybridization and introgression from introduced and invasive species [142,143,144,145,146]. Although it is not entirely new, the current scale is unprecedented. Some taxa have already been impacted in the past. This is most likely true for Pelodiscus Asian softshell turtles. These turtles have been farmed and traded for hundreds of years. As a result, different species and local genetic lineages have been moved, leading to other taxa and lineages in captivity and the wild [147,148].

Similarly, the historical introduction of Mauremys reevesii to Japan resulted in massive hybridization with the native [149]. Another historical case of human-mediated admixture of genetic lineages is known from European pond turtles (Emys orbicularis). The non-native populations on the Balearic Islands, which were most likely introduced during Roman times [150], are of admixed origin [151]. Another population with genetic signatures of an old or ancient introduction of Emys orbicularis hellenica was discovered near Rome [151,152] within the range of another subspecies (Emys orbicularis galloitalica). However, unlike in the past, when only a few turtle species were affected, genetic pollution has become a big problem in protecting wildlife in recent years. This is because of the huge pet and food trade and increased human mobility.

Today, genetic pollution is also caused by well-meaning augmentation of endangered local turtle populations with genetically mismatched individuals (typically, but not exclusively, from non-coordinated actions by turtle enthusiasts), the release of surplus or abandoned genetically divergent pet turtles, and also by large-scale releases of confiscated turtle shipments, especially in Southeast Asia. Some endangered Emys orbicularis populations are on the northern edge of their range [153,154], and there is genetic evidence for restocking with multiple subspecies; in southern France [152,155], there is evidence of restocking with non-native Emys orbicularis hellenica rather than native Emys orbicularis. Examples of genetic pollution caused by abandoned pet turtles include Chrysemys picta bellii from British Columbia, introgressed by non-native subspecies [49], and Antillean (Trachemys), introgressed by Red-Eared Sliders (Trachemys scripta elegans) [156]. As previously stated, some cases involving European pond turtles are related to genetic contamination caused by abandoned pet turtles. In Taiwan, hybridization between Mauremys reevesii and Mauremys sinensis has been observed in the wild in released trade animals [157]. According to Reference [158], preserving well-defined genetic lineages, subspecies, and species that are mostly pure and not hybridized is critical. Therefore, in Malaysia, the two introduced species potentially cause genetic pollution.