166 H. Duffy et al.
trawl nets, with 45% of fishers citing this type of gear as a source of bycatch. Of the fishers interviewed, 86%perceived that marine turtle populations were decreasing. Atotal of 244 bycatch incidents were reported in the sur-
vey data, with 75 of 221 interviewees reporting turtle by- catch, although there was potential for double-counting given that multiple respondents could have referred to the same bycatch incident and that individual fishers could use multiple types of fishing gear. The majority of bycatch consisted of green turtles (60%, n = 146), followed by hawksbill (28%, n = 67), olive ridley (7%, n = 16), logger- head (2%, n = 5) and leatherback turtles (0.4%, n = 1), with the remainder being unidentified species. When asked about their response to marine turtle bycatch incidents, 45% of respondents indicated they would release an accidentally caught live turtle, whereas 24% of respondents indicated they would consume it (the remaining 31% gave other responses). We also identified bycatch hotspots from the data based
on the number of bycatch incidents reported. These specific sites were Thmor Reang (n = 13) and Keo Phos (n = 10)in Preah Sihanouk province, Koh Ses (n = 12) in Kampot prov- ince and Koh Sdach (n = 11), Thmor Sor (n = 10) and Koh Kras (n = 10) in Koh Kong province (Fig. 1).
Discussion
Evidence from historical sources and provincial consultations
Through a combination of anecdotal historical sources and the research conducted by Fauna & Flora, the University of Cambridge and the Fisheries Administration since 2010, the available evidence points to a significant decline of the marine turtle population in Cambodia, with nesting being severely reduced and intense fishing pressure resulting in both the intentional and accidental catch of marine turtles. Systematic and repeated harvesting of eggs is recog- nized as a potential driver for population declines through the direct removal of hatchlings (Chan & Liew, 1996). The provincial consultations indicated that eggs were still occasionally harvested and consumed, although not in the same volume as historically. This is probably a result of diminished availability of eggs and nesting sites, rather than any legislative or cultural shifts. These consultations also identified diverse additional threats that were perceived to be contributing to turtle population decline, particularly trawl fisheries, longline fisheries and intensified coastal development.
Nesting beach surveys
Based on the nesting surveys, current nesting numbers ap- pear to be low, with only one nest having been identified by
surveys in the last decade, although it should be noted that survey effort has been constrained on many remote beaches and offshore islands because of the limited availability of trained surveyors and the inaccessibility of certain sites. Of concern is the identification of plastic waste build-up on all of the beaches surveyed so far, which would probably hinder the activities of nesting adults and emerging hatch- lings (Duncan et al., 2017). Although there are no systemat- ic data on the impacts of plastic on marine turtles in Cambodia, entanglement in nylon ghost fishing gear has been observed in Koh Rong (Mulligan & Longhurst, 2014). Locating and managing the remaining nesting sites must be a priority to prevent further population declines, in- cluding regular monitoring, targeted removal of plastic waste and dedicated site-based protection to prevent further new coastal development. Conservation work continues to focus on identifying active nesting beaches, including through the recruitment and training of locally based volun- teers, who are best placed to regularly survey isolated sites. The nesting site observed in February 2022 will become a focal point for further investigation and management, to re- cord any further nesting activity in the area and respond immediately to any local threats. The trialling of aerial drone surveys is planned for 2023, as an approach that could in- crease the power of our surveys and help us record any turtle nesting signs more efficiently (Schofield et al., 2019; Bogolin et al., 2021).
Bycatch surveys
Responses from 2016–2018 suggest that c. 45%ofturtle bycatch incidents are likely to result in release, which is consistent broadly with the release rates reported for 2010 (Fauna & Flora International, 2011) and those docu- mented by the ongoing Fauna & Flora marine turtle sight- ing database up to 2022. However, there is some evidence in the bycatch surveys conducted by Fauna & Flora of a longer-term cultural or attitudinal shift, with retention of captured turtles for sale or consumption potentially be- coming more accepted amongst respondents than previ- ously (pre-2000s). The release of captive wild animals, includingmarine turtles, for spiritual or religious purposes is widespread in South and East Asia (Stuart et al., 2002; Chan, 2006; Fauna & Flora International, 2011). Cambo- dians release turtles during Buddhist ceremonies to bring happiness and good luck (Tana, 1997;Try, 1999;Pich, 2002), with Buddhism being the religion of the majority of fishers in the country. In the Koh Rong Archipelago, these merit releases appear to have occurred historically, with turtles being adorned with Buddhist offerings and fishers even carving names and dates on the carapaces to identify the individual in the event of recapture elsewhere (Diamond et al., 2012). However, it has been reported that this practice has waned in coastal communities because of
Oryx, 2023, 57(2), 160–170 © Fauna & Flora International, 2023. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605322000862
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