Assessing Nesting Status of Green Turtles, Chelonia Mydas in Perak, Malaysia

The nesting of green turtle (Chelonia mydas) was monitored from 1998 untill 2013 along the beaches of Pasir Panjang, Segari, Perak. The objective of the study is to assess the nesting status of green turtles in Perak, Peninsular Malaysia in terms of total nests, eggs, survival hatchings, and density of visitors. A total number of green turtle nests found for 16 years were 1,019 nests and varied from 10 to 220 nests per year. Meanwhile, the sum of eggs collected for 16 years were 107,820 eggs, and varied from 553 to 20,881 eggs per year. The temporal pattern of nesting indicates year-round nesting in Perak in most years within the 16 years period. The peak season of nesting was estimated to occur between May and June. Survival hatchlings varied from 23.33% (2,071 hatchlings) to 55.03% (5,018 hatchlings) from 1998 to 2013. The density of visitors was not uniformly distributed among the years, and shows a sign of decline especially from 2006 onwards. This publication provides basic knowledge of green turtle nesting population in Perak, and would be helpful in upgrading the conservation program in Malaysia. In future, we hope 1) for an increase in manpower to obtain accurate nesting records along the nesting beaches during nocturnal survey and, 2) to include the breeding biology data such as nest placement, emergence hour, and morphological characteristics of green turtle.


INTRODUCTION
In Malaysia, the green turtle is widely distributed, with the prominent nesting population being in Sabah (specifically at Turtle Islands Park), Sarawak (specifically at Talang Satang National Park), and Terengganu (specifically at Redang Island and Setiu). On the west coast of Peninsular Malaysia, there are three highlighted marine turtle nesting beaches facing the Straits of Malacca; these are Penang Island, Perak, and Melaka. The green turtle majorly resides in Penang Island (specifically in Kerachut and Teluk Kampi; Sarahaizad et al. 2012a) and Perak (Pantai Remis;Chan 2006) with minor landing of olive ridley. Meanwhile, the hawksbill species majorly resides in Melaka with no records of green turtle nesting (Mortimer et al. 1993). It was previously mentioned that only the green and olive ridley species can be found in Perak state (Pusat Pengurusan Penyu, Segari, Perak Darul Ridzuan 2007), which is similar to the adjacent state, Penang Island. However, the exact population in Perak is still vague due to minimal published information, thus difficult to compare both the states. In comparing to the other nesting sites in Malaysia, the population status of marine turtle was stated in terms of nesting per years, and published by Mortimer et al. 1993 (Melaka), Setiu, Terengganu (Aini Hasanah et al. 2014), Redang Island (Chan 2010), Penang Island (Sarahaizad et al. 2012a), Sabah (Chan et al. 1999) and Sarawak (Leh 1994). Due to the above reason, the rational of this study is to observe on the nesting status in Perak with full co-operation by the Department of Fisheries. In addition, we also would like to observe the current conservation plan implemented by the Department of Fisheries in Turtle Management Centre, Pasir Panjang (Perak) and to provide recommendations for further improvement. The objective of the study is to assess the nesting status of the green turtle in Perak, Peninsular Malaysia in terms of nests, eggs, survival hatchings and density of visitors. Currently, the green turtle is listed as Endangered or Vulnerable in the IUCN Red List of Threatened Species worldwide (Mortimer & Donnelly 2008).

Study Sites
Perak is one of the Malaysian States located on the west coast of Peninsular Malaysia. Perak borders Kedah at the north, Kelantan and Pahang to the east, and Selangor to the south, and faces the Straits of Malacca to the south. Pasir Panjang beach in Segari is the main turtle landing area in Perak (Pusat Pengurusan Penyu, Segari, Perak Darul Ridzuan 2007). The research was performed at Pasir Panjang beach, Segari (located in Perak), with the help from the staff of Turtle Management Centre.
Realising the threat of extinction to the marine turtle species, the area of Pasir Panjang beach in Segari was develop as a research centre for marine turtles. The Turtle Management Centre (Latitude: 4.3470, Longitude: 100.5860) was initiated in 1990, developed under the management of Department of Fisheries. The centre is located on a 2.4-hectare area and has interpretative pond and exhibition gallery to disseminate information to create awareness amongst public. To date, this Turtle Management Centre has contributed in enhancing the turtle population through hatching and release programs, gathering information through research and monitoring, conducting public awareness events, and spreading the conservation to the young generations. The information of Turtle Management Centre was obtained from a booklet published by Pusat Pengurusan Penyu, Segari, Perak Darul Ridzuan (2007).

Beach Patrol
Nesting data from 1998 until 2013 was obtained from the Department of Fisheries with their permission to publish the results. The Department of Fisheries hired local residents and licensed eggs collectors for nocturnal beach monitoring along the beach of Pasir Panjang. The beach patrol was done daily by the local patrollers (1-2 persons), and surveyed along the Pasir Panjang beach (Fig. 1), which is approximately a 5.6 km stretch (Latitude: 4.3465, Longitude: 100.5664) between 21:00 to 06:00 hrs. Nesting activity was observed approximately at 5-10 m distance to avoid distraction to adult turtle during the process. Clutch size was only relocated after the turtle had finished nesting, compacted down the sand using flippers, and returned to the sea. This procedure was conducted to avoid disturbance to the turtle, as the creature is very sensitive to any source of light (i.e. torch light, hand phone light, camera flash) (Chan et al. 1999;Wang & Cheng 1999). Artificial lighting (Law et al. 2010) and animal disturbance (Maros et al. 2003;Donlan et al. 2004;Margaret et al. 2012;Olgun et al. 2016) such as dog, otters, pigs, and foxes also discouraged the nesting of turtles. The standard procedure of beach patrolling in accordance to the Peninsular Malaysian Standard Guidelines of Turtle Management (Sukarno et al. 2007), and similar methods can be found in the study of Chen and Cheng (1995); Wang and Cheng (1999); Cheng et al. (2009). Identification and tagging method was not implemented for adult green turtle in Perak, similar to marine turtle population in Setiu (Aini Hasanah et al. 2014). Adult turtles landed were tagged on both front flippers, and the tagging method is hoped to be included in future as it assists in tracking and identification purpose. Number of nests and eggs were then counted. Eggs were removed carefully with a minimal orientation from the natural nests to the pile. The pile full with eggs was then transported to the hatchery for immediate incubation. The Department of Fisheries pays RM2 per egg to the licensed eggs collector (Department of Fisheries personal communication). For hatchery monitoring, four staffs (two staffs to work at one time) were hired to look after the eggs incubation inside the hatchery from predator disturbances. The staff also looks after the new emerging hatchlings, and transfers them to a Styrofoam box, to prepare them to be released to the sea between 1-7 days. Survived hatchlings from the hatchery were counted based on the formula: [Total Hatched eggs -Total Dead Hatchlings = Survival hatchlings]. In Perak, morning surveys were performed every day to identify the overlooked or misplaced nest from the previous night. The beach was surveyed from 08:00 to 09:00 hrs. Local residents (i.e. member from Unipro Fishing Club, Segari) occasionally provided information on the nocturnal and daytime nest found. Due to the problems of limited manpower and uncontrolled eggs poaching, all nests found were relocated and in-situ method was not performed in Segari.

Data Analysis (Between 1998 untill 2013)
For the data analysis between 1998 until 2013, record of nesting was unavailable for years 2002-2003, 2004-2005, and 2010-2011 as the data was misplaced and also due to some technical errors (i.e. unreadable data). Due to the above reason, data of nesting, survival hatchlings, and density of visitors for year 2002-2003, 2004-2005, and 2010-2011 were excluded from the analysis. The analysis was only conducted for the survived hatchlings; because the data provided by the Turtle Management Centre was incomplete analyse the hatching success, dead hatchlings, and unhatched eggs.

Density of Visitors
Density of visitors was obtained from the Turtle Management Centre. Visitors entering the Turtle Management Centre, Segari were required to fill in the record book at the entrance. Total visitors per year were analysed based on the record (from year 1998 until 2013).

Statistical Analysis
Data was analysed using the SPSS 17.0 version and Microsoft Excel. Spearman's rank correlation coefficient was used to analyse the correlation between nesting and eggs. Spearman's Rank coefficient was chosen because the number of nests was small in some years and fluctuated annually. Independent sample t-test was performed to test the significant difference between the highest and lowest number of nesting, and eggs per year. One-way ANOVA was used to analyse the uniformity for nesting, eggs, and density of visitors, since the data was not normally distributed, K-S= p > 0.05. One sample chi-squared test (i.e., goodness-of-fit test) was used to analyse the uniformity of the survival hatchlings by investigating the number of eggs collected per years.

Overall Result of Nesting Distribution
Based on the data obtained from the Department of Fisheries, the number of nesting, eggs, survived hatchlings, and density of visitors in Perak were analysed. According to Table 1 Lastly, year 2006-2007, recorded only 84 cumulated nests, which is the lowest nesting record (mean = 14.00 ± 7.21, median = 16.00). There is no data of nesting for some years due to misplaced original data and unclear data recorded. Due to the incomplete date, accurate nesting result for year [2002][2003][2004][2005], and 2010-2011 as shown in Table 1 was unable to be added up. The highest record for the sum of nesting per-two months was 135 nesting (occurred in May-June of 1998-1999), followed by 100 nesting (occurred in March-April of [2000][2001], and 92 nesting (occurred in March-April of 1998-1999) ( Table 1). The largest sum of eggs collected were 37,177 eggs (in year 1998-1999), followed by 32,231 eggs (in year 2000-2001), 16,033 eggs (in year 2008-2009), 13,794 eggs (in year 2012-2013), and lastly 8,585 (in year 2006-2007). A significant difference between the highest and lowest sum of nesting (1998-1999 and 2006-2007), t(5.238) = 2.110, p < 0.001, and for sum of eggs (1998-1999 and 2006-2007), t(5.335) = 2.122, p < 0.001 was identified. Spearman's correlation was used to test the significant correlation between sum of nesting and sum of eggs per two-years as shown in Table 1. There was a significant correlation between them, Spearman's rank correlation coefficient (ρ) = 0.904, n = 30, p < 0.001, which proves that there is an increase in the number of eggs by increase the nesting aborted on the beach by turtles. Meanwhile, the yearly percentage of nesting and eggs is illustrated in Figure 3. The highest nesting was collected in 1999 with 220 nests (21.59%) and 23,622 eggs (21.91%) and the lowest was collected in 2007 with 10 nests (0.98%) and 533 eggs (0.51%). In addition, a significant difference between the highest and lowest number of nesting, t(11.125) = 3.245, p < 0.001 and eggs, t(11.045) = 3.363, p < 0.001 as identified.

DISCUSSION
The nesting per year varied from 10-220 nesting (Fig. 2) Liles et al. 2015) and remoteness from human areas (Sarahaizad et al. 2012a) are the conditions that attract marine turtles to land. Perak has longer beach (approximately more than 6 km), containing natural and fringed preserved vegetation, remote locations, and exposed to minimal human disturbances, are among the reasons suggested for higher population of green turtle in Perak compared to Penang Island. It is mentioned that olive ridley (Lepidochelys olivacea) do nests in Perak (Pusat Pengurusan Penyu, Segari, Perak Darul Ridzuan 2007). Probably due to the missing records, nesting of olive ridley was not found between 1998-2013 in the data provided. Olive ridley might have nested in Pasir Panjang waters, as Penang Island (the adjacent beach) recorded the landing of olive ridley in , 2005, 2007, and 2009(Sarahaizad et al. 2012a. Both locations share the same oceans and face the Straits of Malacca. Increasing the manpower and standardising the methods of data recording may solve the problems of overlooked data. In addition, the current situation of poaching rate in Perak is unable to be estimated, as the data was not provided. Therefore, it is hoped that the poaching record could be included in the future. The pattern of nesting in Perak is estimated to be have a year round nesting (Table  1) similar to the green turtle in Thailand (Yasuda et al. 2006). The peak in Perak was estimated between May and June, which is almost similar to graph of peak nesting season as illustrated in Penang Island (Sarahaizad et al. 2012a). Since Perak and Penang Island are located facing the Straits of Malacca, the similar peaks nesting might relate to the monsoon in Malaysia. The northeast monsoon in Malaysia occurs end of the year until beginning of the year (November until March) and the winds are stronger than Southwest monsoon that occurs from May until September (MOSTI 2017). Therefore, turtle possibly prefer nesting between May-September, and avoid nesting between November to March during extreme condition of high humidity and low temperature at nesting sites. Previous study proves that humidity at the nesting sites are the critical factors effecting nesting choices (Lopez Castro et al. 2004). The similar peak of nesting (May-July) is also reported to occur for hawksbill population in Melaka (Mortimer et al. 1993), which is located at the west coast of Peninsular Malaysia. Warmer water temperature during the inter-nesting interval  and temperature of sand  is presumed to promote nesting of marine turtles. In addition, tidal pattern, lunar, and solar are strongly linked and interact with each other as spring tide (highest tide) occurs during the full moon, and neap tide occurs during the during the first and last quarter of the lunar phase (Law et al. 2010). Turtle generally nest above the high tidal line (Lopez Castro et al. 2004) as emerging at the highest tides will minimise the distance and duration of crawls (Law et al. 2010). Even though the preference of nesting related to tidal pattern in Perak was not measured, it is believed that tidal line and lunar factors influence the nesting, because turtle in Penang Island shows a positive sign of emerging during the high tide (Sarahaizad et al. 2012b).
The percentage of yearly survival hatchlings fluctuates (23.33% to 55.03%, Table 2). Some years had lower survival hatchlings; due to lack of manpower to control nest from natural predator disturbances that attacks nest inside the hatchery. In Perak, predators that harm lively hatchings are monitor lizard, ghost crab, and red ants. Monitor lizards (Varanus saluator) are capable to eat the newly emerged hatchling, attracted from the eggs mucous smells, while groups of red ants bite the lively hatchlings. Ghost crab (Ocypode sp.) is able to dig a hole, eats the eggs, or drags the lively hatchling into their burrow. Yearly hatchlings survival could be increased with a proper conservation method following the Peninsular Malaysian Standard Guidelines of Turtle Management (Sukarno et al. 2007). In-situ was not conducted in Perak, therefore relocated or Ex-situ nest needs to follow proper guidelines for a maximum hatching success such as incubation at standard nesting depth (suggested to be 65cm depth, Cheng et al. 2009). For example, reduce orientation during the eggs handling and incubating relocated eggs immediately (Chan et al. 1985;Sukarno et al. 2007), avoid sand temperature from exceeding 33°C during incubation as it will decrease hatching success (Matsuzawa et al. 2002), and protect nests with plastic mesh to avoid attack from predators (Chan 2010).
In addition, equal hatchling sexes produced from the hatchery's plot is very important for adult mating process in future when the turtle reaches maturity [approximately 20 years, Davenport (1997)]. Evolutionary theory predicts that male and female offspring should be produced at a 1:1 ratio (Hawkes et al. 2013). Higher incubation temperature (> 30°C) tends to produce more females while low incubation temperature (< 28°C) tends to produce more males (Mrosovsky & Yntema 1980). This may be based on a mechanism known as temperaturedependent sex determination, TDS (Hawkes et al. 2013) where equal sexes between males and females will be produced. It is suggested the temperature (produced at 50:50 sex ratio) is very close to 29°C . In future, it is hoped that the eggs survivorship results could be recorded separately, between survival hatchling produced from covered hatchery and uncovered hatchery's plot. Sand temperate monitoring is important for the equal hatchlings sex's production to ensure sustainability of the species.
Rate of nesting population may show a recovery trend by following proper protection from human hazards such as exploitation of eggs and turtles at nesting site of USA, Japan, Australia, Costa Rica, and Hawaii. (Chaloupka et al. 2008) For example, turtle in Hawaii has increased dramatically over 32 years since the protection began in 1978 (Balazs & Chaloupka 2006). Turtle population has not been exposed to human exploitation (turtle harvesting at foraging grounds), harvesting of nesters and eggs, and nesting habitat destruction for a certain time. This resulted in the increase of nesting abundance in Hawaii probably from the increased female nester survival since harvesting of turtles in the foraging grounds was prohibited since the mid-1970s (Balazs & Chaloupka 2006).
As illustrated in the graph (Fig. 4), the number of visitors is declining by years. Involvement and support from the locals is important to strengthen the awareness and conservation of marine turtles. In future, an active conservation program by the Department of Fisheries such as conducting hatchling release program, exhibition, and organize international volunteering program involving locals and foreigners such as in Chagar Hutang, Redang Island (Chan 2013) for long term benefits are conducted. From these programs, the society is educated to protect this endangered species. Conservation in Sabah Turtle Island, is one of the successful programs where the nesting sites are fully protected by the Sabah Government. This implementation was due to a recovery trend of marine turtle population in the 1980's (Chan 2006), resulting from the right conservation methods been forced with the involvement of society in the previous years. Few recommendations are listed below to improvise the management of Turtle Management Centre, Segari, Perak.  Chen and Cheng (1995), and Olgun et al. (2016). 5. Garbage (i.e. plastic, styrofoam, plastic container, boxes, papers, glasses) that is obviously seen along the Pasir Panjang beach might affect the nesting due to pollution at nesting ground and feeding oceans. Regular beach cleanliness activity is able to reduce pollution at nesting ground. 6. It is hoped that adult landing could be tagged in future, so the landed adults are estimated. In addition, the migration of turtles may be detected, whether the green turtle in Perak have migrated to Penang Island, or vice versa. This co-operation can be made, as both nesting locations are located at the northern region of Peninsular Malaysia. 7. Juvenile turtles (approximately more than 7 years age) were found to be kept inside the pool with no artificial nesting ground built for them to land and perform nesting. These turtles may face difficulty to survive if released to the sea. The natural navigation may be interrupted since they were kept in the pool as soon as they were hatched. Marine turtles will move to waters in closer vicinity to nesting beaches (Bowen et al. 2005) and ready to lay eggs as they approach maturity. Therefore, it is suggested for the artificial nesting ground to be included in the pool for them to lay eggs. This may be referred to the example such as in Port of Nagoya Public Aquarium, where both males and females will mate inside the aquarium, and lay eggs at the artificial nesting ground (Sarahaizad personal observation). This project was one of the successful project in Japan. 8. Lastly, it is suggested to avoid splitting the eggs into smaller sizes for eggs incubation, as it reduces the hatchling energy reserved when they enter the sea (Rusli et al. 2016). This may have an implication to the hatchling's survival. Whole eggs incubation with a proper nesting without splitting the eggs is recommended, as it is also able to produce high rates of hatching success (Sarahaizad & Shahrul Anuar 2014).

CONCLUSION
In this paper, the nesting density, eggs, survival hatchlings, and density of visitors in Segari Perak between 1998 until 2013 was estimated. This publication provides a basic knowledge of nesting population in Perak, and can be used as a reference for upcoming studies. By updating the current nesting status, the results might be helpful for purpose of conservation. The ideas given in this paper may provide benefit for the reason to upgrade the management of Turtle Management Centre and Department of Fisheries in future. A serious conservation in Perak is needed to prevent the species from declining by involving local and international participants.