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Turtle population declines are attributable to: centuries of international trade in hawksbill carapace and plastron scutes (‘tortoiseshell’), a practice which intensified from the mid-1960s until 1992 (Meylan & Donnelly 1999; Mortimer 1984); and exploitation of green turtle calipee, an edible gelatinous substance found under the plastron, formerly used in Europe to make “turtle soup,” especially at the turn of the 20th century (Hornell 1927). Unlike most populations of hawksbills that nest at night, Seychelles hawksbills nest in the daytime, which makes them particularly vulnerable to capture (Mortimer & Bresson 1999) and to disturbance.

Prior to 1994 when Seychelles passed the “Wild Animals (Turtles) Protection Regulations” that banned the killing of turtles throughout the country, sea turtles were only protected within the nature reserves at Curieuse and Ste. Anne National Parks, at Aride and Cousin Island Special Reserves, and at Aldabra Atoll (Mortimer 1984). In 1979 Curieuse Island was designated a Marine National Park, and Park Rangers were stationed on the island to protect turtles and other resources. With a land area of 2.86 km2, Curieuse is the fifth largest of the inner granitic islands and is a popular destination for tourists. It has a rocky coastline interspersed with seven nesting beaches with a total length of approximately 2,060 m. At Curieuse, situated 1.2 km north of the second largest human population centre on Praslin Island (Fig. 1), turtles have been subjected to poaching by local people, though to a lesser degree than at other islands; and tourists also cause inadvertent disturbance to nesting turtles. Even though turtle protection has not been perfect (Mortimer 1984, 2004), Curieuse has managed to retain one of the most important hawksbill nesting populations in the granitic islands of Seychelles and it also hosts a small number of nesting green turtles.

Figure 1. Maps showing the locations of: (upper) Curieuse Island relative to the three most populated islands of the granitic Seychelles (Mahé, Praslin and La Digue); and (lower) the seven turtle nesting beaches of Curieuse island: Grand Anse, Anse Papaie, Baie Laraie, Anse Mandarin, Anse St. Jose, Anse Cimitier/Caiman, and Anse Badamier. The total area depicted in these maps represents <0.5% of the total Exclusive Economic Zone of Seychelles (1.4 million km2).

The hawksbill nesting season in Seychelles spans September to April, with a peak during October to January at both the Inner Islands (Mortimer & Bresson 1999) and the Amirantes group (Mortimer et al. 2011a). In contrast, seasonal patterns of green turtle nesting vary not only between sites in the western Indian Ocean region (Dalleau et al. 2012) but to some degree also from one year to the next (Mortimer et al. 2011b; Mortimer 2012). During the three decades (30 nesting seasons) from 1979-1980 to 2009-2010, the Seychellois Park Rangers recorded turtle track counts and tagged turtles at Curieuse while carrying out their anti-poaching patrols during the peak months of the hawksbill nesting season. In most years surveys at Curieuse were incomplete and provided only minimum estimates of numbers of egg clutches laid, except for hawksbills during 1981-1983 and 2001-2003 (Mortimer 2004; Rulie 2002), and more recently for both hawksbills and green turtles since 2010 when Seychelles National Parks Authority (SNPA) joined forces with Global Vision International (GVI), a conservation and community development organization that now collects data on behalf of SNPA.

In this study at Curieuse, we assessed the nesting of hawksbills during the 44 months between September 2010 and April 2014, and of green turtles during the 33 months from September 2012 to May 2015, using the following parameters: a) spatial distribution of nesting activity on seven beaches; b) seasonal distribution of green turtle nesting; c) numbers of egg clutches laid by each species; and d) estimated numbers of females nesting annually. We also recommend long term conservation management strategies for nesting turtles and their habitats at Curieuse National Park.

Data for this study were collected from September 2010 through May 2015 by a total of 35 GVI staff and over 350 volunteers under the guidance of SNPA. Surveys were conducted most frequently and consistently during the hawksbill nesting season, September through April, when Anse Cimitier/Caiman was surveyed 1-2 times per week, Grand Anse and Anse Papaie 3-5 times per week, and Baie Laraie and Anse St. Jose 7 times a week. Anse Mandarin and Anse Badamier were not surveyed in 2011 and 2012, but were surveyed 1-2 times per week during 2013 through mid-2015. With this survey schedule we are confident in our assessment of hawksbill nesting activity. During the non-hawksbill season (May through August), beaches were not surveyed regularly before September 2012. But, from September 2012 through mid-2015, all beaches were surveyed at least 1-2 times per week; and because most green turtle body pits remain visible for at least a week, we are confident this survey regime adequately documented all green turtle nesting activity between September 2012 and May 2015 (Fig. 3).

Each turtle track observed was recorded and classified according to species and also whether or not eggs were laid. Those data enabled an assessment of the spatial distribution of nesting emergences and egg laying amongst the seven beaches and an estimate of the total numbers of egg clutches laid by each species each season. Prior to 2010 and during the 2013-2014 season, flipper tags were applied to all nesting hawksbills encountered at Curieuse. New tags were not applied during the 2010-2011, 2011-2012, and 2012-2013 seasons; but throughout the study, tag numbers were recorded whenever a previously tagged turtle was intercepted. No nesting green turtles were intercepted.

The spatial distribution of hawksbill egg clutches laid each season at the seven beaches is presented in Fig. 2. Total activity varied between seasons, but spatial distribution was relatively consistent. Grand Anse hosted 75-81% of egg clutches laid and Anse Papaie, 8-12%. Table 1 compares the beaches in terms of relative density of hawksbill tracks and egg clutches laid per season, and nesting success (defined as percent of emergences that resulted in egg clutches laid). Nesting density was highest at Grand Anse and Anse Papaie, which together comprise only 23% of the total beach length, but hosted 83-93% of each season’s total egg clutches (Fig. 2, Table 1). Nesting success was also highest at Grand Anse, at 52%.

Table 1. Seasonal nesting activity recorded at each of the beaches of Curieuse Island over a four-year period. For each beach the following are indicated: beach length (m); mean estimated numbers and density of turtle tracks produced and egg clutches laid; and mean percent nesting success (defined as percent of nesting emergences that resulted in egg clutches laid).

Figure 2. Percentages of total hawksbill turtle egg clutches laid each season at each of seven beaches. Legend indicates total numbers of egg clutches laid during each of the four seasons.

On average, over the four hawksbill seasons, with each season defined as July to June annually, but with almost all nesting activity during the months of September to April, there was an average of 381 hawksbill nesting emergences (sd = 97.0; range = 312-522) and 187 egg clutches laid (sd = 67.8; range = 128-282) annually (Table 2). During the 33 month-long comprehensive green turtle track study, 69 nesting emergences and 29 egg laying events were recorded (Fig. 3). These data suggest that, although green turtles nest year-round, their nesting season can be defined as April to March annually, with most nesting during the months of June to February. It follows that during the two green turtle seasons for which we have complete surveys (2013-2014 and 2014-2015) an annual average of only 30.0 turtle tracks (range = 6-54) and 13.5 egg clutches (range = 4-23) were produced (Fig. 3).

Bracketed estimates of total females nesting per season at Curieuse were calculated from track count data based on the following assumptions: a) that the average female hawksbill lays 3-4 egg clutches in a season, using data from Cousin (Mortimer & Bresson 1999) and Bird (JA Mortimer & R Bresson, unpublished data) islands; and b) that the average green turtle lays 3-5 clutches per season, using data collected at Aldabra Atoll (Mortimer et al. 2011b). In this manner we estimated that an average of 53.4 individual female hawksbills (range = 46.7-62.3) (Table 2), and 3.4 female green turtles (range = 2.7-4.5) nested annually. Because these calculations assume that the full complement of each female’s egg clutches were laid at Curieuse, however, they would underestimate female numbers if there is significant movement of females between Curieuse and other islands. During our study, 88 known individual tagged hawksbills were encountered, some of which had been previously tagged at other sites in the inner island group, including Bird, Cousin, Cousine, Mahé, Praslin, and Ste. Anne islands, all within a distance of ~85 km from Curieuse (members of Turtle Action Group of Seychelles (TAGS), unpublished data). But the frequency of these inter-island movements has not yet been quantified.

Table 2. Current status of the hawksbill nesting population as indicated by total numbers of turtle tracks produced and egg clutches laid during each of four nesting seasons for July 2010 to June 2014. Numbers of nesting females are estimated based on a mean of 3.5 and a bracketed mean of 3-4 egg clutches per female (Mortimer & Bresson 1999; JA Mortimer & R Bresson, unpublished data).

Figure 3. Seasonal distribution of green turtle egg clutches and tracks (nesting emergences) recorded each month at Curieuse during the comprehensively surveyed period from September 2012 to May 2015.

We consider our four-season survey of nesting hawksbills at Curieuse to be a robust estimate of annual nesting activity (Table 2) given that the remigration intervals (the time between the consecutive nesting seasons of individual females) for hawksbills nesting in the inner islands of Seychelles are typically two to three years (Mortimer & Bresson 1999). In contrast, our data quantifying annual nesting activity and seasonality for green turtles are the first collected at Curieuse and represent only two full seasons. Remigration intervals for green turtles in the Inner Islands of Seychelles are unknown. We found that, on average, fewer than five female green turtles nested annually, with much variation between seasons (Fig. 3). In the Western Indian Ocean (WIO), green turtles typically nest during every month of the year, with seasonal peaks that vary between sites (Dalleau et al. 2012), between seasons and even within the boundaries of a given site (Mortimer et al. 2011b; Mortimer 2012).

Our estimated average of 53.4 hawksbills nesting annually (Table 2) suggests a 50-100% increase in the nesting population since 1984 when an estimated average of 20-30 individuals nested each season (Mortimer 1984). Higher rates of population increase during the same three decades, however, have been recorded at nearby hawksbill rookeries where the nesting populations have been better protected over longer periods of time. At Cousin Island there was an eightfold increase documented between 1968 and 2008 (Allen et al. 2010), and at Aride Island a similar increase was recorded during the same period (Mortimer 2004; Island Conservation Society (ICS), unpublished data). This raises the question of why the rate of increase for Curieuse Island is only a fraction of that recorded at Cousin and Aride islands.

Likely explanations involve a combination of poaching, human disturbance and habitat limitations. Cousin and Aride islands were both designated as Special Reserves, in 1975 and 1979, respectively, which afford them the highest level of protection of any natural site in Seychelles. Turtles at Curieuse received legal protection in 1979, but heavy poaching continued until the mid-1990s (Mortimer 1984, 2004), and Curieuse is not yet free of poaching as indicated by the remains of three hawksbill turtles we encountered during the 2011-2012 nesting season.

Perhaps the most important issue, however, is the relatively unique vulnerability of the daytime nesting hawksbill populations of Seychelles to the negative impacts of human activity and disturbance, unsupervised tourism, and unregulated coastal development. These females, which nest almost exclusively in the daytime, will readily abort a nesting attempt when they detect movement (Mortimer 2004). In Seychelles, high-density hawksbill nesting beaches have only persisted where they are not subjected to high levels of human activity or coastal development. Diurnal hawksbill nesting is compatible with tourism at sites where tourist density is low (Mortimer 2004), e.g., at Bird Island with 26 chalets and 5 km of nesting beach, at exclusive five star private islands that cater to low volume tourism, or in the Special Reserves where tourist behaviour is strictly regulated. But, concentrated nesting has all but disappeared on the more densely populated islands of Mahé, Praslin and La Digue (Mortimer 1981, 2004; members of Turtle Action Group of Seychelles (TAGS), unpublished data).

Tourists to the Seychelles National Parks provide important revenue. Some 30,000 tourists visited Curieuse annually during 2007-2013 and each paid an entrance fee of approximately $15 USD. At Curieuse, tourists are free to visit on any day of the week between 9 am and 5 pm (although visiting hours are rarely enforced); and they may access the island aboard a variety of watercraft including taxi boats, private yachts, and local tour boats. Their impacts on nesting turtles include disturbance from beach and boat traffic, swimmers and snorkelers, and pollution from lighting and noise. In contrast, tourists only visit Cousin and Aride islands on specially designated visiting days, and only as members of guided tour groups that are not allowed to roam unsupervised. Nesting activity at Curieuse was once more evenly distributed amongst the seven beaches (Mortimer 1984, 2004; Rulie 2002), but the high concentrations of tourism activity at Anse St. Jose and Baie Laraie have become incompatible with diurnally nesting hawksbills (Mortimer 2004). Almost 85% of the estimated 195 egg clutches laid annually at Curieuse are now concentrated on only 480 km of nesting beach at Grand Anse and Anse Papaie (at an average density of 34 clutches per 100 m per year). This demonstrates the significance of Grand Anse/Anse Papaie as a regional hotspot for turtle nesting, and highlights the importance of protecting this critical nesting habitat.

Currently, the Regulations of Curieuse National Park prohibit visitors from accessing Grand Anse and Anse Papaie. We commend the Government of Seychelles and SNPA for their efforts to protect this critical nesting habitat. But, there is no guarantee that it will remain intact for nesting turtles into the future. In Seychelles, there are fewer restrictions on development of land within a National Park than within Special Reserves. The current legislation for Curieuse under the National Parks and Nature Conservancy Act (1969) states that a National Park is “an area set aside for the propagation, protection and preservation of wildlife, or the preservation of places or objects of aesthetic, geological, prehistoric, historical, archaeological or other scientific interest, for the benefit, advantage and enjoyment of the general public.” Unfortunately, this does not exempt National Parks from commercial development. In theory, plans for development would have to be approved by the Seychelles National Environment Commission (NEAC), but the Minister has the final decision. There are no specific guidelines for important sea turtle nesting areas within the current legislation; and although the protected area policy of Seychelles is currently under review, no major changes are in motion regarding land development within National Parks.

We do not believe the current legislation provides the necessary safeguards for the nesting beaches at Curieuse under National Park status. We suggest that new legislation be adopted that allows for complete protection of key marine turtle nesting habitat, or that the status of Curieuse Island be re-classified in full or in part based on its national and international importance as nesting habitat for the Critically Endangered hawksbill. Indeed considering that Curieuse is not the only Seychelles National Park that hosts globally important turtle nesting habitat we believe it would be prudent to reassess the current legislation. The Ste. Anne and Silhouette National Parks both host hawksbill nesting populations of similar magnitude to that of Curieuse and have had hotel developments and marinas proposed adjacent to critical nesting habitat. These issues highlight the inadequacy of Seychelles National Park legislation to propagate, protect and preserve wildlife.  

Protection of nesting beaches is perhaps the most essential component of any sea turtle conservation program (Mortimer 2000). Our results showed that Curieuse may host as many as 80 individual nesting hawksbills annually along with a number of highly endangered Inner Island nesting green turtles. With this in mind we recommend the following actions:

1) Provide formal protection in perpetuity for the critical nesting habitat at Grand Anse and Anse Papaie. This should preclude any coastal development behind or on these beaches, and a minimum of human activity at the beach. Ideally, no boat traffic should be allowed within 400 m of this small stretch of coastline in order to minimize interference with turtle mating, internesting behaviour and hatchlings. But currently there is no legislation with which to regulate offshore activity in the vicinity of a National Park.

2) Continue to count tracks and tag turtles at all nesting beaches of Curieuse on a regular and consistent basis in order to assess long-term trends in the population and to provide surveillance against poaching. Annual and long-term monitoring is vital for documenting population trends.

3) Enforce rules that prohibit tourist access to Grand Anse and Anse Papaie. A vigilant Park Ranger at Baie Laraie would prevent access of tourists to adjacent Anse Papaie, especially at low tide when tourists typically try to approach the beach by sea.

4) Provide appropriately placed information boards that: a) inform tourists of restricted access zones; and b) describe a “Code of Conduct” for when in the presence of nesting turtles. Ensure Rangers and volunteers are available to explain the least intrusive way to view nesting turtles.

5) Keep all nesting beaches clear of obstacles, such as fallen trees and rubbish that impede turtle access to the beach platform, especially at Grand Anse and Anse Papaie. Fallen trees and branches downed by a violent storm in 2003 remain problematic at Grand Anse, and need to be removed.

In summary, we recognize that Curieuse National Park is one of the most important nesting sites for hawksbills and green turtles of the Inner islands of Seychelles. The Republic of Seychelles was recently named one of five small island nations declared world leaders in conserving threatened species (Rodrigues et al. 2014). The increase in nesting abundance described here for Curieuse and other nearby islands in the Praslin group is evidence of the effort dedicated to the protection and conservation of sea turtles in Seychelles by Government, parastatal organizations (e.g., Seychelles National Parks Authority (SNPA), NGOs (e.g., Global Vision International, Island Conservation Society, Nature Seychelles, and others), conservation scientists, and also community stakeholders. We highlight the need to protect critical turtle nesting habitats of national and global significance and to adjust national legislation accordingly.

Acknowledgements. The Seychelles National Parks Authority and Global Vision International are gratefully acknowledged for providing financial, logistical and personnel support. We would also like to acknowledge the hard work of many staff and volunteers involved in the data collection process.

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