121 Terrestrial Report Final

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GVI Seychelles Curieuse

Terrestrial Conservation Expedition

Phase Report

2012

Submitted in whole to

Global Vision International

Seychelles National Parks Authority (SNPA)


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Produced by

April J Burt Curieuse Island Science Coordinator

And

Dan White Base Manager Christophe Mason-Parker Country Director

Ant Hardman Dive Officer Rachel Walls General Staff

Michele Beyer Scholar Susie Lilley Scholar

Conor Price Volunteer Duncan Hall Volunteer

Vicki Lazarus Volunteer Veronica Ramsbottom Volunteer

Saskia Geluk Volunteer

GVI Seychelles - Curieuse/Marine and Terrestrial Conservation Expedition

Address: GVI c/o SNPA, PO Box 1240, Victoria, Mah, SeychellesEmail:[email protected]

Web page:http://www.gvi.co.ukandhttp://www.gviusa.com
mailto:[email protected]:[email protected]:[email protected]://www.gvi.co.uk/http://www.gvi.co.uk/http://www.gvi.co.uk/http://www.gviusa.com/http://www.gviusa.com/http://www.gviusa.com/http://www.gviusa.com/http://www.gvi.co.uk/mailto:[email protected]


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Executive Summary

This report summarises the science programmes conducted by the Seychelles

Global Vision International (GVI) Expedition on Curieuse Island, between September

2011 and May 2012,

The terrestrial expedition continued the on-going Coco de Mer census by adding a

further 1247 to the so far 688 palms surveyed. The results continue to show an even

sex ratio with over half being juveniles. Of the juvenile palms 3% are seedlings

indicating a small amount of rejuvenation. A key finding within this data set is the

0.7m difference in average trunk height between male and female trees; female

being taller. This is the opposite of the data findings found for the praslin populations

which show that male trees are significantly taller than female trees. The mean

number of nuts each female tree produces is 0.2.

The mangrove distribution and composition surveys are now complete totalling

5.8km of transects. Rhizophora mucronata is the most abundant species followed

closely by Brugiera gymnorhiza. From the current data a slight zonation of species

can be seen with Rhizophora mucronata dominating the seaward zone, Avicennia

marinathe central zone and Brugiera gymnorhizathe landward zone.

During the 2011-12 nesting season a total of 393 emergences were recorded, 80%

of which were recorded on Grande Anse. Of these emergences 205 were

successfully laid nests. The hatchling success was 96% overall however the

relocated nest hatchling success was only 4%. The most suitable nesting beach was

determined by evaluating the amount of emergences each female made in order to

lay one successful clutch of eggs. The most suitable nesting beaches are Grande

Anse and Anse Papaie respectively and the worst beach was Anse Cemetiere. Since

identification pictures began to be collected in 2010 there has been 53 different

females encountered nesting on Curieuse. Based on the number of nests laid a

conservative estimate of annual nesting population was made; around 50 females

nested on Curieuse during the 2011-12 nesting season. The importance of Curieuse

as a nesting rookery for Hawksbills is apparent; recommendations are made for

future monitoring and conservation management.


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List of contents

Executive Summary .............................................................................................................. 3

List of contents ...................................................................................................................... 4

List of Figures ....................................................................................................................... 5

1. Introduction ....................................................................................................................... 6

2. TERRESTRIAL SURVEY PROGRAMME ......................................................................... 7

2.1 Introduction .................................................................................................................. 7

2.1.1 Importance of Coco de Mer ................................................................................... 7

2.1.2 Importance of Mangrove forests ............................................................................ 8

2.1.3 Importance of Sea Turtles ..................................................................................... 8

2.2 Aims ............................................................................................................................ 9

2.3 Methodology .............................................................................................................. 10

2.3.1 Study Sites .......................................................................................................... 10

2.3.2 Training............................................................................................................... 10

2.3.3 Survey Methodology ........................................................................................... 11

3. Results ............................................................................................................................ 14

3.1 Coco De Mer ............................................................................................................. 14

3.2 Mangroves ................................................................................................................. 15

3.3 Curieuse 2011-2012 Turtle nesting season ............................................................... 17

3.3.2 Population estimation .......................................................................................... 18

3.3.3 Hatchling success ............................................................................................... 18

3.3.4 Nesting Hawksbill Identification ........................................................................... 20

4. Discussion ...................................................................................................................... 23

4.1 Coco de Mer .............................................................................................................. 23

4.2 Mangroves ................................................................................................................. 23

4.3 Turtles ....................................................................................................................... 24

5. Conclusion and future recommendations ........................................................................ 25

6. References ..................................................................................................................... 26


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List of Figures

Figure 1: Courtesy of Google Images 2011. Curieuse Island nesting beaches. A= Anse Jose, B= Anse

Caiman/Cemetiere, C= Grande Anse, D= Anse Papaie and E= Anse Laraie.

Figure 2: Graph showing the amount of Coco de Mer palms surveyed over time from 2009 until

Phase 4 2011.

Figure 3: Pie chart showing the sex ratios and breakdown of lifestages for juvenile coco de mer trees

on Curieuse Island.

Figure 4: Map showing the areas of Curieuse Island which have been surveyed for Coco de Mer.

Figure 5: Graph showing the amount of mangrove surveys carried out for each expedition phase.

Figure 6: Map showing the mangrove survey progress on Curieuse Island in 2011.

Figure 7: Map showing basic species distribution of mangroves. Colour denotes the main species

found in that area not the only species. Rhizophora mucronata, Avicennia marina, Xylocarpus

granatum, Xylocarpus molluccensis, Bruguiera gymnorhiza & Lumnitzera racemosa.

Figure 8: Graph showing the abundance of each species recorded on transects through the

mangroves.

Figure 9: Graph showing the distribution of activity throughout the previous two nesting seasons.

Figure 10: Graph showing the beach specific number of successful lays for the 2011-2012 nesting

season.

Figure 11: Graph showing the beach specific hatchling success rate expressed as a percentage of

hatchlings that made it out of the nest alive.

Figure 12: Graph showing the beach specific mean number of emergences per female per clutch.

Table 1: Table containing Tag information for nesting females encountered on Curieuse Island

between October 2010 and March 2012.

Table 2: Table containing the allocated code for each photo identified nesting female from October

2010 to March 2012. Underlined photo ID numbers indicate where photo ID has been successful in

matching two turtles.


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1. Introduction

Global Vision International (GVI) Seychelles comprises two expeditions based on separate

granitic islands. The Curieuse expedition is based on a small granitic island of the same

name located to the north of the larger island of Praslin, with base camp located at Anse

Jose within the Curieuse Marine National Park. This marine park has been designated since

1979 and represents an area of 14.7km2

All of GVIs scientific work in the Seychelles is carried out on behalf of our local partners and

at their request, using their methodology; GVI supplies experienced staff, trained volunteers

and equipment to conduct research in support of their ongoing work. GVIs key partner is

the Seychelles Centre for Marine Research and Technology (SCMRT), the research arm of

SNPA (Seychelles National Parks Authority). Additional local scientific partners are theMarine Conservation Society Seychelles (MCSS) and the Seychelles Fishing Authority

(SFA).

In October 2010, two British Technology and Education Council (BTEC) courses were

introduced into the programme, as well as Short-Term Marine Internships.

Seychelles National Parks Authority (SNPA): A local parastatal organisation partly

funded by the government, encompassing the Seychelles Centre for Marine Research

and Technology (SCMRT) and the Marine Parks Authority (MPA). These organisations

have the respective aims of conducting marine research in the Seychelles and management

and protection of the marine parks. The coral, fish and Coco de Mer monitoring carried out

for SCMRT constitutes the majority of the work conducted by the volunteers.

Marine Conservation Society Seychelles (MCSS): A local NGO that carries out

environmental research in the Seychelles, currently monitoring whale sharks, cetaceans and

turtles around Mah. GVI assists with all three of these research programmes by reporting

incidental sightings of cetaceans and whale sharks, documenting the presence or absence

of turtles on every dive throughout the phase, conducting in-water turtle surveys and nesting

turtle surveys.

Seychelles Fishing Authority (SFA): The governing body which oversees the

management and regulation of commercial and artisanal fisheries in the Seychelles. This

government agency is directly concerned with setting the catch, bag and seasonal limits that

apply to local stocks on an annual basis, as well as managing the international export


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industry that is generated from the harvest of fisheries across the Seychelles Exclusive

Economic Zone (EEZ).

2. TERRESTRIAL SURVEY PROGRAMME

2.1 Introduction

The Seychelles Islands are the only mid-oceanic granitic islands in the world. Isolated for 75

million years, the Seychelles now hosts a unique assemblage of flora and fauna, many of

them extremely primitive. Such ancient species include endemic palm trees such as the

Coco de Mer (Lodoicea maldavica). However, 200 years of human settlement has exerted a

serious influence on the native biota of these islands. Habitat loss and fragmentation, as well

as invasive species, have caused several extinctions and reduced populations of many

species to extremely perilous levels. Human use continues and poses a serious threat to the

Seychelles native flora and fauna.

Curieuse Island is a small granitic island (1.78 sq mi) in the Seychelles, close to the north

coast of the island of Praslin. Curieuse is notable for its bare red earth intermingled with the

unique Coco de Mer palms, one of the cultural icons of the Seychelles, only being present

on the two islands.

In 1979 Curieuse and surrounding waters were declared the Curieuse Marine National Park

in order to protect the native wildlife. Today it is the home of roughly 500 Aldabra Giant

Tortoise, 300 of which live at the Ranger's Station and approximately 200 in the wild. Around

Curieuse the sea grass and reef habitats provide ideal location for sea turtles and the

beaches are an important turtle nesting location. Another key part of the Curieuse marine

ecosystem are the mangrove forests, a group of terrestrial trees adapted to cope with high

salinity and low oxygen environments. They are found most extensively around the lagoon

area and bridge the gap between the marine and the terrestrial environment, playing a key

role in maintaining optimum reef building conditions for corals.

2.1.1 Importance of Coco de Mer

Meaning coconut of the sea, Coco de Mer is an endemic palm carrying the largest seed

pod in the world. Taking 20-40 years to reach reproductive maturity, these palms, which can

reach up to 30m high, have a slow reproductive rate. Renowned as a flagship species for the


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and Bresson, 1999), but represents only 27% of the estimated total number of hawksbills that

nested in Seychelles during the early 1980s (Mortimer, 1984). The exploitation of hawksbill turtles in

Seychelles became particularly intense after the mid-1960s with the advent of the mask and snorkel,

spearguns, underwater lights, outboard engines, and the high prices paid for raw shell (Mortimer,

1984). Mortimer (1984) estimated that 4771% of the total estimated annual nesting population in

the granitic Seychelles Islands was killed during the 198082 nesting seasons. Destruction of

breeding and foraging habitat, especially in the granitic Seychelles, is an increasingly serious problem

(Mortimer, 1998).

There are also significant nesting populations of the "endangered" Green Turtle (Chelonia mydas).

Although Loggerhead and Leatherback Turtles feed in Seychelles waters, no breeding activity has

been recorded. Green Turtles have been heavily exploited for their meat in the inner islands of

Seychelles since the 17th

century and are a now very rare in the inner islands of Seychelles.

Unfortunately, the few green turtles remaining in the inner islands are still intensely exploited and

may well disappear completely if that trend is not reversed. Both Green and Hawksbill turtles are

nationally protected in the Seychelles and were granted full legal protection in the 1994 Turtles

Protection Regulations

Curieuse Island waters are home to both Green and Hawksbill turtles as the surrounding reefs and

sea grass beds provide ample food sources. The beaches also provide a nesting habitat for both

species but particularly the Hawksbills. This alone is enough to highlight the importance of the

island. Current data trends show an increase in nesting activity on Curieuse and so it is now of

paramount importance to continue studying the nesting population and uphold all conservation

measures to protect this globally important species.

Hawksbill Turtles in Seychelles and along the East African coast nest primarily during daylight hours

compared to Hawksbill Turtle populations elsewhere, which tend to nest either strictly or primarily

at night (Mortimer & Bresson, 1999). Green Turtles on the other hand nest primarily at night

(Mortimer, 1984). Historical data gathered in Seychelles shows that both Hawksbill and Green

Turtles can nest during any month of the year. Hawksbill Turtles, however, show a distinct peak in

nesting from October to February (Mortimer, 1998).

2.2 Aims

The aims of the terrestrial expedition of phase 114 on Curieuse, Seychelles include the

following:-

Assessment of nesting turtle populations on Curieuse.


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Assessment of turtle hatchling success on Curieuse Island.

Assessment of the species composition in the mangrove forests around Baie Laraie.

Assessment of the Coco de Mer population and distribution.

2.3 Methodology

2.3.1 Study Sites

Figure 1: Courtesy of Google Images 2011. Curieuse Island nesting beaches. A= Anse Jose, B=

Anse Caiman/Cemetiere, C= Grande Anse, D= Anse Papaie and E= Anse Laraie.

2.3.2 Training

2.3.2.1 Terrestrial Health and Safety

All Expedition Members on the terrestrial program are taught high levels of safety

precautions to work safely on beaches or walking off-path to sites. They are also provided

with first aid training through the Emergency First Response first aid course taught on-site

2.3.2.2 Terrestrial Species identification

All Expedition Members are required to learn species of turtle, mangrove and Coco de Mer.

Training is initially provided in the form of presentations, workshops and informal discussion


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with the expedition staff. Self study materials are also available in the form of textbooks and

fact sheets.

Turtle track identification is tested using actual track markings on land, for which a high level

of competency is required. Expedition Members are initially accompanied by staff members

on mangrove, Coco de Mer and turtle walks; their observations and responses are noted

and staff supervision continues until the Expedition Member has demonstrated accurate

identification of all necessary species, tracks and procedures.

2.3.3 Survey Methodology

2.3.3.1 Coco de Mer Population Mapping

As part as our on-going support for SCMRT we continue to map the population distribution ofCoco de Mer palms. Located throughout most of the island, expedition members can begin

mapping at any location. Once a palm is found it is identified as either a Juvenile, Male or

Female species and an individual identifying code it is painted on the trunk - or on a young

leaf - for future recognition. The location of this palm at the trunk will be saved into a GPS.

The length of the longest leaf, number of dead leaves and number of green leaves are also

recorded.

If the palm is an adult, the trunk girth will be measured at breast height (150cm) and the

trunk height recorded. If the palm is particularly tall then the trunk height and leaf length is

measured from 10 metres away using a clinometer. If the palm is a female additional data

collected includes the number of infructescenses with bearing nuts, number of double nuts,

number of aborted nuts, and number of nuts that are either primary, maturing or ripe. If the

plant is male then the number of flowering catkins is recorded.

2.3.3.4 Beach Patrols for nesting Turtles

The October to December period coincided with the Hawksbill turtle nesting season. Beachpatrols of the known nesting beaches were conducted as often as possible during this time.

This land-based turtle monitoring work includes beach walks, documentation of nesting

tracks and investigation of newly hatched clutches. The surveys are conducted on foot, with

the teams walking along the upper beach searching for signs of tracks or body pits, on the

main beach and also within the coastal vegetation. Tide timetables are consulted to

determine the state of the tide at the time of each patrol.


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All tracks, nest sites and nesting turtles encountered on the patrol were recorded. Any

sightings made during the return along the beach should be included in that patrol data.

Members are taught to scan the beach regularly during the patrol to spot newly emerging

turtles.

If tracks are found, track width is estimated from an average taken from three measured

widest points in the sand. If a dig or nesting spot is found, then this is also recorded. The

emergence date should be estimated where the turtle is not actually seen. Where a

complete track ends in a suitable nest sight and there are signs of digging and covering, it

can be assumed that the turtle has nested. Emergence types are recorded as follows....

Half Moon A: Wandering but no digging

B: U-shaped crawl to the high tide line

ESBO: Emergence stopped by obstacle

Did Not Lay C: Considerable disturbance, evidence of digging (body pitt & eggchamber) no covering.

D: Evidence of digging, no covering.

Laid E: Considerable disturbance, evidence of digging and covering.

Variations Probably Did Not LayProbably Laid? Cannot tell if laid or not

All tracks are disguised so that it cannot be mistaken for new tracks later on and that it will

not lead possible poachers to a nest location. Further to the above all laid nests should be

recorded using a GPS and the number of attempts for each activity recorded. The nest

should be marked to show it has been recorded.

If a nesting turtle is encountered on a beach patrol, expedition members are taught

appropriate behaviour. They must only approach the turtle from behind, and only once the

turtle has begun laying, and continue to remain quiet, low and out of its sight. Measurements

are taken from the longest point along its carapace, tag numbers or evidence of a previous

tag from its fin, evidence of disease/ scarring/injuries or other distinguishing features. If it

was possible, members were encouraged to count the number of eggs being laid. Whilst the

turtle is laying photographs (without a flash) of each cheek should be taken and any

distinguishing features.


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For each patrol undertaken the date, patrol number, time of day, names of recorders, beach

visited, if tracks were found (along with width, likely species, emergence time, evidence of

digs, and evidence of a successful nest, turtle carapace length and tags/scars/disease.

Hatchling Success

Hatchling success can be difficult to gauge especially because the hatchlings mostly

emerge at night. It can be done however by excavating nests which have hatched recently.

When hatchlings emerge they leave behind a sink hole (the sand sinks down to fill the space

where the eggs were). Ideally you would monitor a nest around its due date and look out for

the sink hole.

When excavating a nest record the number of:

1. Live hatchlings (stragglers)

2. Dead hatchlings

3. Egg cases (hatched eggs)

4. White eggs (unfertilized)

5. Black eggs (fertilized but embryo died)

6. Dead pipping (died during hatching process)

7. Alive pipping (still trying to hatch from egg)

The number of egg cases plus the number of black and white eggs should represent the

total number of eggs laid by the female (ideally this would have been recorded when the

nest was laid). The following equation will give you hatchling success rate:

( )

3.3.3.5 Mangrove Species & Distribution Methodology

This phase we completed the surveys and are now able to produce an overview of the

distribution & abundance of mangrove species surrounding the old turtle pond in Baie Laraie.

Starting from the most eastern inland point of the mangroves, three surveyors walk in a

westerly direction (270) in a line spaced 3 metres apart. They stop every two metres and

the person in the centre records numbers and species of any mangrove trees themselves


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and the surveyors to the left and to the right. The transect continues until the edge of the

mangroves, whether this be on the seaward or inland side. Transects run parallel,

approximately 10 metres apart, and are marked, both by GPS point and visual tag, (e.g.

cloth tags tied to a tree) every 20 metres to ensure they can be followed again accurately.

3. Results

3.1 Coco De Mer

During the January to April survey period 812 coco de mer palms were surveyed which brings

the total number surveyed by GVI up to 1993. Figure 2 shows a large increase in survey effort

over the past two years. Average dimensions for both male and female trees are very similar but

overall female trees have taller trunks (4.21m) than males (3.52m) and slightly longer leaves

(females 3.4m and males 3.2). The average number of nuts per female is 0.2 (N=223).

Figure 2: Graph showing the amount of Coco de Mer palms surveyed over time from 2009 until Phase 4 2011.

The sex ratios remain equal as stated in

previous reports and Fig. 3 shows that the

majority of unsexed trees are classed as

juveniles (more than 3 leaves and no trunk).

The proportion of seedlings recorded is

relatively low reflecting an unequal balance

among each lifestage.

Figure 3: Pie chart showing the sex ratios and

breakdown of lifestages for juvenile coco de mer

trees on Curieuse Island.

0

100

200

300

400

500

600

700

800

900

2009 2010 2011 2012 (Jan-April)

Male

14%

Female

15%

Juvenile

46%

Seedling

3%

Immature

5%

Not

Recorded

17%


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The distribution of the Coco de Mer trees so far surveyed can be seen in Fig.4, it is clear from this

map that a proportion of the coordinates recorded were inaccurate due to GPS error. It is important

to map the coordinates in order to have a clear idea of which parts of the island need to be

surveyed.

Figure 4: Map showing the areas of Curieuse Island which have been surveyed for Coco de Mer.

3.2 Mangroves

The Curieuse Island Mangrove transects began in February 2011 and are now fully completed

totalling 5.8 km of transect. Fig.5 shows the amount of mangrove completed during each survey

phase showing that during phase 114 & 121 the majority of the survey work was completed.

Incidentally these were periods when the marine project wasnt running and therefore more time

and people were allocated to this project.

Figure 5: Graph showing the amount of mangrove surveys carried out for each expedition phase.

0

1000

2000

3000

4000

5000

111 112 113 114 121

Metrescompleted


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The map below (Fig 6) shows an approximate diagram of transects completed in the mangroves. The

map indicates that the species distribution and abundance surveys have recorded a thorough

representation of the Curieuse Island mangrove forest.

Figure 6: Map showing the mangrove survey progress on Curieuse Island in 2011.

A study using GPS to mark the key areas for each species would be beneficial, however for now to

use as a basic reference, a map showing species distribution based on personal observation is seen

below in Fig. 7.

Figure 7: Map showing basic species distribution of mangroves. Colour denotes the main species found in that

area not the only species. Rhizophora mucronata, Avicennia marina, Xylocarpus granatum, Xylocarpus

molluccensis, Bruguiera gymnorhiza & Lumnitzera racemosa.


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The completion of the mangrove surveys means that a summary can be made in terms of species

abundance and predominance. Figure 8 represents the abundance of each species and shows that

Rhizophora mucronata is the most abundant species, followed by Bruguiera gymnorhiza and

Avicennia marina (40%, 35% and 19% respectively).

Figure 8: Graph showing the abundance of each species recorded on transects through the mangroves .

3.3 Curieuse 2011-2012 Turtle nesting season

3.3.1 General results

Results for the 2011-2012 nesting season show that both Hawksbill and Green turtles have

nested on Curieuse. The total number of emergences recorded was 393 and of these 205 were

recorded as lays or probable lays. The data shows a slight rise in activity from the previous

nesting season. Fig.9 shows that November and December consistently are the peak nesting

period for Curieuse Island.

Figure 9: Graph showing the distribution of activity throughout the previous two nesting seasons.

0

100

200

300

400

500

600

700

800

900

A. marina B.

gymnorhiza

C. tagal L. racernosa R.

mucronata

S. alba Xylocarpus

sp.

Numberoftreesontransect

0

1

2

3

4

5

6

Activitiesp

erday


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The nesting activity distribution for the 2011-2012 nesting season is similar to the previous

years (see Fig. 10) with 80% of activity taking place on Grande Anse. As mentioned in GVI

114 report there seems to be a negative correlation between beach activity and human

interference.

Figure 10: Graph showing the beach specific number of successful lays for the 2011-2012 nestingseason.

3.3.2 Population estimation

Population Estimation: There is insufficient data to determine how many clutches the average

Curieuse Hawksbill lays per nesting season but by basing our estimate on the average clutch data of

3.6, acquired on Cousin Island 1994 study (Mortimer and Bresson), we can estimate that

approximately 56 females laid 205 nests during the 2011-2012 nesting season.

3.3.3 Hatchling success

The 2011-2012 Hawksbill nesting season is the first year in which hatchling data has been collected.

This data collection presented a learning curve for GVI staff members which will enhance the

following season hatchling data collection. Mean clutch size was obtained in two ways; firstly a mean

clutch size was obtained from personal observation of nesting turtles and secondly by the excavation

of hatched nests. The mean clutch sizes were 154 (N=17) and 168 (N=57) respectively. Further study

is needed to see whether recording clutch size by nest excavation is accurate enough bearing in

mind the potential for removal of eggs from the nest by crabs during the incubation period. In this

case however it would seem that mean clutch size has not been impacted by this when compared

with the original clutch amount. The solution to this is to gain both original clutch size and eventual

clutch size for each nest and ascertain whether any eggs have been taken. Overall hatchling success,

recorded as the percentage of hatchlings which left the nest, was calculated to be overall 96% (StDev

0

20

40

60

80

100

120

140

160

Grande Anse Anse Papaie Anse Laraie Anse Jose Anse

Caiman/Cimitiere

No.ofNests


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5.4). Not included in this was a relocated nest hatchling success rate of only 2%. Fig.11 shows a

beach specific breakdown of hatchling success showing that Anse Jose has the lowest success rate.

Further study is required in this area. The mean nest depth was 56cm (N=37, StDev=5.5).

Figure 11: Graph showing the beach specific hatchling success rate expressed as a percentage of hatchlings

that made it out of the nest alive.

Beach suitability can be measured by calculating the number of times each female emerges in order

to lay one clutch of eggs. The lower the number of emergences per clutch is the more suitable the

beach is, reflecting a lower abundance of aborted attempts. Fig 12 shows that the least suitable

beach for laying is Anse Cemetiere & Caiman and the most suitable beaches are Grande Anse, Anse

Papaie and Anse Laraie. These results perhaps address a link between hatchling success and nesting

success but further studies are needed to determine whether the factors affecting nesting success

may also affect hatchling success.

Figure 12: Graph showing the beach specific mean number of emergences per female per clutch.

70

75

80

85

90

95

100

Grande Anse Anse papaie Anse Jose

%hatchlingsuccess

0

1

2

3

4

56

7

8

Grande Anse Anse Papaie Anse Laraie Anse Jose Anse Cemetiere/

Caiman

No.o

femergencesperclutch


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3.3.4 Nesting Hawksbill Identification

Since October 2010, 20 females have been encountered with metal tags located in their front

flippers. The tag information recorded in Table 1 shows that most tagged turtles have only been

encountered once so far however on three occasions we have re-encountered tagged females. The

time between encounters varies but our most commonly encountered female (SEY9431/9432) had

18 and 14 days intervals respectively. Although most turtles were tagged on Curieuse others have

migrated from St Anne and Mahe. The following tables have been updated since the previous report

to include the January-March section of the 2011-12 besting season.

Tag numbers Date/s Encountered Tag Origin

0129/0130 27.10.10 Curieuse 1992

305 6.11.10 ?

E1897 6.12.10 Curieuse 1995

SEY2626/2627 17.10.11

16.11.11

Curieuse 2007

E2631/2630 16.11.10 Curieuse 2004

E2634/2635 5.12.11 Curieuse 2007

4770 11.11.10 Mahe 1999

SEY4944 18.2.11 Curieuse 2002

SEY6302 20.11.11 Curieuse 2002

SEY6304 5.12.11 Curieuse 2004

6305 19.10.10 ?

SEY 6959 18.1.11 Cousine 2004

7509/7508 18.10.10

3.11.10

Curieuse 2004

SEY7510 5.12.11 Curieuse 2004

7545/7540 12.11.10 Curieuse 2004

SEY9431/9432 24.10.11

9.11.11

23.11.11

St Anne 2006

Table 1: Table containing Tag information for nesting females encountered on Curieuse Island between

October 2010 and March 2012.

Since photo ID pictures began being taken in 2010, 61 nesting females have had left and

right cheek shots taken. Recent comparisons of the photographs revealed that seven turtles


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which were untagged could be recognised from different nesting attempts making a total of

53 separate nesting females that have so far been encountered; each now allocated with an

ID number for future use.

Photo ID Number Date/s

Encountered

Beach/s

Encountered

Tag Numbers

CURHB1 27.10.10 GA

CURHB2 27.10.10 GA 0129/0130

CURHB3 27.10.10 GA

CURHB4 2.11.10 GA

CURHB5 8.12.10 GA

CURHB6 3.11.10 GA 7508/7509

CURHB7 6.11.10 GA

CURHB8 10.11.10

26.11.10

GA

GA

CURHB9 12.11.10 AP 7545/7540

CURHB10 12.11.10 AP

CURHB11 15.11.10 GA E2631/2630

CURHB12 15.11.10 GA

CURHB13 30.11.10 GA

CURHB14 6.12.10 AC E1897

CURHB15 6.12.10 AC

CURHB16 27.10.10 GA

CURHB17 6.11.10 GA

CURHB18 11.11.10 GA 4770

CURHB19 22.11.10 GA

CURHB20 14.01.11

28.01.11

GA

GA

CURHB21 3.2..11 AC

CURHB22 18.2.11 AP

CURHB23 18.2.11 GA SEY4944

CURHB24 31.1.11 GA

CURHB25 25.10.11 AJ SEY9580

CURHB26 30.11.11 GA


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16.01.12

CURHB27 2.12.11 GA

CURHB28 16.1.12 GA

CURHB29 21.10.11 ALCURHB30 24.10.11

9.11.11

23.11.11

GA

GA

AJ

SEY9431/9432

CURHB31 17.10.11

16.11.11

GA

AP

CURHB32 9.11.11

23.11.11

GA

GA

E2626/2627

CURHB33 11.11.11 AP

CURHB34 14.11.11 AP

CURHB35 14.11.11 GA

CURHB36 16.11.11

2.12.11

GA

GA

CURHB37 20.11.11 AJ SEY6302

CURHB38 23.11.11 GA

CURHB39 23.11.11 GA

CURHB40 25.11.11 AJ

CURHB41 30.11.11 GA

CURHB42 2.12..11 GA

CURHB43 5.12.11 GA

CURHB44 5.12.11 GA E2634/2635

CURHB45 5.12.11 AP SEY6304

CURHB46 5.12.11 AP 645-SEY7510

CURHB47 21.10.11 GA

CURHB48 9.11.11 GA

CURHB49 28.1.11 GA

CURHB50 2.11.10 GA

CURHB51 28.10.11 AJ

CURHB52 30.11.11 GA

CURHB53 29.01.12 AC


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Table 2: Table containing the allocated code for each photo identified nesting female from October 2010 to

March 2012. Underlined photo ID numbers indicate where photo ID has been successful in matching two turtles.

4. Discussion

4.1 Coco de Mer

The expansion of the GVI Curieuse island conservation project has increased the capacity of the field

work quota and taken our total of Coco de Mer palms surveyed so far up to nearly 2000. In terms of

analysis this is a substantial sample size and can be used to begin to understand the Curieuse Island

population further. A comparison of Curieuse data with results found in the two Praslin populations

(Fond Ferdinand & Vallee de Mai) shows some distinct differences. It is obvious from visual

observations that Curieuse palms are smaller than the FF and VM populations; they are also slower

growing and produce fewer seeds (Fleischer-Dogley et al, 2011). In a study by Savage & Ashton

(1983) it was stated that male Coco de Mer palms grow taller than female trees due to a difference

in age and survival. A re-interpretation of this data by Silverton (1987) states that the difference in

average size may actually be a consequence of sexual dimorphism due to slower growth rates (a

result of energy expended in seed growth) or that higher female mortality selects for smaller

stature. None of these arguments holds for the Curieuse population which shows that female trees

are on average taller than male trees by 0.7m. A study by Fleischer-Dogley et al (2011) on Curieuse

palms showed a similar result of a 0.5m difference although there sample size was much smaller

(N=30male & 21female). The difference between height means was not then recorded as significant

but with the current results it could indeed be that females on Curieuse are significantly higher than

males; a curious result! Further analysis is needed. The very low (relative to the other two

populations) number of nuts recorded for the Curieuse population is concerning. If these nuts are

taken for sale to tourists then Curieuse has no chance of regeneration.

4.2 Mangroves

The Curieuse Island mangroves species composition and distribution survey is now completed. The

seaward trees are dominated by R.mucronata, middle mangroves are mostlyA.marina and landward

mangroves are mostly B.gymnorhiza. The distribution map seen in the results section is vital to

demonstrate the current zonation of mangrove species; a GIS map should be generated to show a

more accurate representation. This can then be used as a baseline to determine any future changes

that occur. It was mentioned in the GVI 114 report that the mangroves on Curieuse to not strictly

adhere to an expected zonation pattern; there are inundation channels and areas of raised ground

which are colonised by palms and non-mangrove trees.


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In the past two years the mangrove area has visibly changed; there has been an influx of sediment

(large sand particles) which has covered root systems and changed the topography. There are a

relatively large abundance ofRhizophora mucronata seedlings and saplings which are spreading into

theAvicennia marina area. Further study is needed to measure these changes and monitor the

effects on the mangroves growth and composition.

4.3 Turtles

The importance of Curieuse Island as a nesting rookery for Hawksbill turtles was highlighted in the

GVI 114 report. It is now estimated that 50 hawksbills (probably more) nest on Curieuse annually.

This can be seen as an underestimate when considering that two nesting beaches were not included

in patrols. Likewise it doesnt account for inter-island nesting habits.

There is a marked increase in nesting activity since the previous (2010-2011) nesting season but

inter-seasonal fluctuations in nesting activity are known to occur based on the turtle nesting interval

of two or more years. Fluctuations of 70+ nests have been recorded at Bird Island (Mortimer GEF)

from one nesting season to the next. Grande Anse continues to be the most prolific nesting beach

and results of nesting attempts and hatchling success show it is really a good place for hawksbills to

nest with the least amount of effort.

A study of hatchling success was carried out on Curieuse for the 2001-02 and 2002-03 nesting

seasons for a selection of nests (N=65) overall the hatchling success (hatched eggs) was

approximately 60%. This differs somewhat from the current approximation although undoubtedly

methods differ slightly. The overall hatchling success rate of 96% for the 2011-2012 nesting season

seems to be unnaturally high when compared with past data and other islands. A study by Hitchens

et al (2004) carried out on Cousine Island recorded a hatchling success rate of 70.9% (over three

nesting seasons) and overall translocated nests were more successful then natural nests. This is the

opposite of the Curieuse 2011-12 findings. The lack of hatchling success (4%) for the relocated nest

can be attributed to it being the first to be done by GVI. Further research has now been done and

should future nest relocation be needed then the results should be more promising. An estimation

of hatchling success can be made without seeing the eggs laid as long as you have a mean clutch size

for a sample of clutches which were counted at the laying point. The hatchling data recorded for the

2011-12 nesting season was un-planned; the results therefore can be seen as a test-run for the

following season. With a method planned it should be possible to record hatchling success for each

nest layed, both witnessed and un-witnessed. Hatchling success can then be compared between

beaches.


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The potential for acquiring a really high quality and comprehensive data set is obtainable, it takes

organisation, experience and hard work to gain a full set of nest and hatchling data and GVI staff and

volunteers are able to do this.

5. Conclusion and future recommendations

It is said that protection at the nesting beaches may be the most critical component of any sea turtle

conservation program ( Mortimer 2000), for this reason and the knowledge that Curieuse may be

used by up to 50 or more female Hawksbills annually it is essential to monitor this population and

maintain high standards of conservation. The nesting population estimation for 2011-2012 is a

baseline value but by no means represents what occurs yearly. It is possible that large scale

fluctuations occur in the number of females arriving at nest sites (Limpus & Nicholls, 1988) and

therefore long-term monitoring is essential to document true population change (Meylan &

Donnelly, 1999). With this in mind the following recommendations are made:

1) The nesting beaches continue to be monitored on a regular and consistent basis by both GVI

and SNPA rangers to enable more turtles to be encountered for tag and photo identification.

This will provide vital information on island fidelity and the number of clutches laid per

female. Where possible beach patrols should also include Anse Badamier and Anse

Mandarin to gain a more accurate idea of annual nesting population for Curieuse.

2) On the nesting beaches accessible to tourists there should be information boards detailing

what is the least intrusive way of viewing nesting turtles and personnel available to enforce

these guidelines.

3) Enforcement of rules with regards to tourist access onto the busiest nesting beaches-

currently at low tide tourists can and do walk around to find a private beach-a constant

presence by Curieuse Park rangers would further mitigate this problem.

4) During peak nesting season Curieuse should be marketed as a vital nesting habitat in order

to educate tourists and create revenue. It would be beneficial to do a turtle presentation

once daily at either the Doctors House or the rangers station. The sale of Curieuse Island t-

shirts and other merchandise as well as guided (small scale) tours on to the private nesting

beaches (with experienced personnel) would provide vital revenue for the Island and justify

the increased focus and resources on protecting the nesting Hawksbills.

5) Cleaning of beaches, removing debris so as to provide a clear pathway for emerging turtles

and encouraging turtles to nest further in-land, away from the high water mark.


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6) A study on erosion and rate of degradation of beaches would be beneficial; to improve the

understanding of nest losses and give an idea of potential future issues. Beach profiling and

beach accessibility surveys should be carried out to establish a baseline.

6. References

Hitchins, P.M., Bourquin, O. And Hitchins, S. 2004. Nesting success of hawksbill turtles (Eretmochelys

imbricata) on Cousine Island, Seychelles.J. Zool., Lond. (2004) 264, 383389.

Limpus, C.J., And Nicholls, N. 1988. The Southern Oscillationregulates the annual numbers of green

turtles (Chelonia mydas) breeding around northern Australia. Aust. J. Wildl. Res. 15:157-161.

Meylan, A. B. And Donnelly, M.1999. Status Justification for Listing the Hawksbill Turtle(Eretmochelys imbricata) as Critically Endangered on the 1996 IUCN Red List of Threatened Animals.

Chelonian Conservation and Biology, 1999, 3(2):200224.

Mortimer, J.A. 1984. Marine Turtles in the Republic of Seychelles: Status and

Management. Publication of the IUCN Conservation Library: Gland, Switzerland. 80pp.+ 4pl.

Mortimer, J.A. and Bresson, R. 1994. The hawksbill nesting population at Cousin Island, Republic of

Seychelles: 1971-72 to 1991-92. Pp. 115-118, in Schroeder, B.A. & Witherington, B.E. (compilers).

Proceedings of the 13th Annual Symposium on Sea Turtle Biology and Conservation. NOAA Technical

Memo. NMFS-SEFSC-341.

MORTIMER, J.A. 1995b. Status of the hawksbill turtle, Eretmochelys imbricata. 1. Status in the

Atlantic and Indian oceans and a historical perspective on global patterns of human utilization. Paper

presented at The International Workshop on the Management

of Marine Turtles 95, 8-10 March 1995, Tokyo, Japan.

Mortimer, J.A. 1998. Turtle & Tortoise Conservation. Project J1: Environmental Management Plan of

the Seychelles. Final report to the Ministry of Environment Republic of Seychelles and the Global

Environment Facility (GEF). January 1998. Volume 1 (82pp) and Volume 2 (Appendices 1-50).

Mortimer, J.A. and Bresson, R. 1999. Temporal distribution and periodicity in hawksbill

turtles (Eretmochelys imbricata) nesting at Cousin Island, Republic of Seychelles, 1971- 1997.

Chelonian Conservation and Biology3(2): 292-298.


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Mortimer, J.A. 2004. Seychelles Marine Ecosystem Management Project (SEYMEMP): Turtle

Component. GEF Final Report, Vol 1: Text, 243 pages. Vol 2: Appendix 1-11, 158 pages.

Rist, L., Kaiser-Bunbury, C.N., Fleischer-Dogley, F.,Edwards, P., Bunbury, N. And Ghazoul, J.2010

Sustainable harvesting of coco de mer, Lodoicea maldivica, in the Vallee de Mai, Seychelles. Forest

Ecology and Management260: 2224-2231.

Savage, A.J.P, Ashton, P.S.,1983. The population structure of the double coconut and some other

palms. Biotropica 15: 15-25.

Silverton, J. 1987. Possible sexual dimorphism in the Double Coconut: Reinterpretation of the data of

Savage and Ashton. Biotropica, Vol.19. No.3: 282-283.

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