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Nesting of marine turtles was considered common on the outer islands of Mauritius with Agalega and St. Brandon thought to be the last rookeries within the Mauritian EEZ (Mangar & Chapman 1996; Bourjea et al. 2008). In 2006, Tatayah & Griffiths (2007) confirmed that at least two species of marine turtle regularly nest on Agalega: greens (Chelonia mydas) and hawksbills (Eretmochelys imbricata). There have been few scientific trips to Agalega, consequently the flora and fauna are still poorly known, and this is especially true for marine fauna. With increasing interest from commercial bodies to develop tourism and other projects on the islands, it is important to document the biodiversity of the islands. In this context, in June 2013, the Mauritius Marine Conservation Society (MMCS) conducted an opportunistic expedition to Agalega via a routine supply ship voyage. The objectives were to record mega-fauna sightings during the boat trip to and from the island and, while there, to collect data on various wildlife activity including turtles, cetaceans and sea birds, in addition to documenting potential threats to the island environment.

Agalega is a coral island in the western Indian Ocean (Fosberg et al. 1983). It is composed of two islands, North (11.7 km2) and South Island (9.3 km2), separated by a shallow pass 1.5 km wide. North Island is long and narrow (12.4 km x 1.6 km), whereas South Island is rounder, measuring 6.6 km x 3.6 km (Fig. 1). Montagne d’Emmerez (15 m) on North Island is the highest point. The islands are bound by sandy beaches of 20-50 m width, and are surrounded by a narrow lagoon, 25-100 m wide (Cheke & Lawley 1983) with areas of both seagrass beds and reef, providing excellent habitat for foraging juvenile sea turtles as well as mating and nesting adults.

Figure 1. Position of Agalega in the Indian Ocean relative to Mauritius.

During the voyage two observers recorded the position and species (where possible) of any turtle sightings. Throughout the seven days on the islands any signs of turtle activity, including nesting attempts, tracks and sightings in the lagoon were noted. Additionally, evidence of poaching (e.g., bones, carapace, egg shells) was recorded while walking the beaches and sand roads of both islands. Global Positioning System coordinates of any activity were recorded and photographs taken. Where possible the curved carapace length (CCL) of dead animals was recorded to give an idea of life stage.

No turtles were observed during the voyage. While on the island turtles were seen in the lagoon on both sides of North Island and an adult green turtle was sighted when it surfaced in the vicinity of the anchored ship off Port St. James while loading for departure. Sightings occurred from the beach near the village of Vingt Cinq, and another three individuals were seen in the lagoon on the west coast during approximately four hours of opportunistic snorkelling by two of us. Based on the size (<60 cm CCL), these turtles were juveniles and at least one was a green turtle. All displayed nervous behaviour, moving away rapidly from the observers.
A number of locations were identified where turtles had been poached. Sites were characterized by palm leaves spread out on the ground to work on (Fig. 2a) and/or bone and carapace pieces in the area (Fig. 2bc). At some sites, the palm leaves were still green and remains were decomposing, indicating recent kills. In total, remains of approximately nine individuals were found along with some eggshells. Sites were distributed around South Island with a single site identified on the southern end of North Island (Fig. 3). However, this site appeared to have been used numerous times over long periods with both green palm fronds and bleached plastron and carapace pieces scattered through the adjacent vegetation. Skull shape and scute patterns on the carapaces indicated all were green turtles. Only four intact shells were recovered and the curved carapace length of these ranged from 92 -104 cm. This size range indicates that these were breeding individuals of green turtles as females reach sexual maturity around 95-100 cm and males at ≤95 cm (Limpus & Chaloupka 1997).

Figure 2. A. Palm leaves used as a working area. B. and C. Bones and carapace of poached animals.

Figure 3. Locations of turtle remains and evidence of poaching on Agalega.

Our observations indicated juveniles use the lagoon area and poaching occurs on the islands, especially on South Island. Agalega has extensive, undeveloped coastline and a small human population (between 250-350); as such it is likely the islands represent an important habitat for marine turtle nesting (Griffiths &Tatayah 2007). However, no tracks were found on the beaches that were covered, but this could be due to the time of year rather than a lack of nesting activity. In the Western Indian Ocean, green turtle nesting shows a variation in the peak of activity between islands (Dalleau et al. 2012) ranging from summer (January) on Tromelin to early winter (June) on Mayotte (Bourjea et al. 2007; Dalleau et al. 2012). While green turtles can nest throughout the year, hawksbill nesting peaks during the summer months (October - February) (Mortimer et al. 2011). Only juveniles were observed in the lagoon area. Agalega has extensive seagrass beds in the pass between the islands and around South island, as well as coral reef structure; this is ideal feeding habitat for both green and hawksbill turtles (Meylan & Donnelly 1999).

A concerned citizen reported that sea turtles coming to nest were regularly flipped on the beach by locals, animals mating in the lagoon would also be caught together, and, in addition, any juveniles encountered were netted, with no consideration for sex and/or size of individuals caught. Furthermore, unlaid and laid eggs are collected for consumption. If this is occurring at a subsistence level, it is expected that there would be limited impact on the general turtle population as there are so few people living on the islands. However, it was suggested that poaching activity increased when the supply boat was due, implying that meat and products were being sold and sent back to the mainland. This represents a potential threat to the population if there is ongoing demand. No hawksbill shells were found. However, they are known to occur in the area and are reportedly caught (Griffiths & Tatayah 2007). As the carapace of this species is highly valued, we suspect it would be removed and sold. Interviews conducted by Griffiths & Tatayah (2007) revealed that locals considered the hawksbill turtle common, more so than the green turtle, which were reported as being seen only occasionally.

The turtles of Agalega are under threat from numerous sources. These include marine debris in the form of plastic and nets and/or fishing gear (Griffiths & Tatayah 2007; Webster & Cadinouche 2013), direct hunting both in the sea and when they come ashore to lay eggs, as well as the poaching of turtle nests and habitat destruction from heavy use of the lagoon by local fishermen with damaging techniques including walking on the reef and dragging nets (Webster & Cadinouche 2013). A further threat involves attacks by domestic but free ranging dogs on nesting females and their nests.

Our observations support those reported by Griffiths & Tatayah (2007) and show that there is turtle activity in this area but also that poaching is a continuing threat. The Mauritian laws protecting marine turtles prohibit the capture, killing or selling of marine turtles or their products. During Griffiths & Tatayah’s visit (2007), interviews with locals revealed that they knew turtle poaching was illegal but continued with the activity due to the potential to earn money. In addition, they said that there was limited enforcement and observations from our expedition show that this is still the case.

On mainland Mauritius, the outlook for turtles is increasingly positive with regular sightings of both hawksbill and green turtles (Webster 2013), the implementation of marine education projects in schools and a general increase in public awareness such as the reporting of injured animals. In February 2014 there was a sighting of a green turtle on one of the southern beaches (R. Mohit, pers. comm.). However, the last confirmed successful nesting on the mainland was in 2007 (Koonjul 2009). Based on observations reported here, the future of those turtles using the outer islands is of concern, especially as these islands are possibly some of the last nesting sites in Mauritius. The level of poaching on the island needs to be determined and a baseline of the turtle population nesting there established. A number of alternatives could be attempted to combat this gap in knowledge. These could include a) training and employing locals in protection and monitoring, b) focused education in schools and environmental awareness programs for all island residents, including those posted from Mauritius, c) regular patrolling and enforcement of Mauritian law protecting these animals with appropriate level consequences to discourage further poaching and d) possible warden posted during peak breeding seasons for both species.

Considering that there are already Coast Guard and Police regularly posted to Agalega, it should not be difficult to also have a ‘nature warden’ posted on one or both islands, similar to that on Round Island Nature Reserve with National Parks Conservation Services and Mauritian Wildlife Foundation. Alternatively, a local inhabitant could be trained to conduct all necessary enforcement activities. Enforcement of current laws is essential not only for the protection of the turtles but also the mangroves, birds, coconut crabs and marine mammals found on and around the island. Should a warden be posted or regular research visits implemented it would provide the opportunity to undertake monitoring to examine the long term condition of both species and their habitats to quickly identify and minimize threats. Mauritius currently has no reliable nesting data (Bourjea et al. 2008) therefore Agalega provides an opportunity to address this gap. Turtle populations should be monitored using methods employed in other areas of the Western Indian Ocean, specifically during peak nesting periods to determine abundance and nesting trends as this will provide maximum data while also assisting in reducing poaching activities. All details collected could then contribute to regional knowledge of turtle movement and population status within the Indian Ocean.

Acknowledgements. Thanks to the Outer Islands Development Corporation for the opportunity to visit the island, Captain and crew of the Mauritius Pride for support during observations on the voyage and island Manager Mr. Carver, National Coast Guard and Police and Mr. X for their local knowledge, comments and assistance while on the islands.

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