The sea turtle hatchling phase is widely known to be the most crucial phase in their life cycle, as scientists believed that only one in a thousand of hatchlings managed to survive till their sexual maturity. In some extreme cases, the figure is said to be only one in five thousands manage to survive. Thus, indicating that research on hatchlings is one of the crucial studies for marine turtle conservation.
Sea turtle hatchlings are vulnerable, both during the crawl (from the nest to the sea) and in the initial phase of their swim away from the beach when they cross shallow, predator rich nearshore waters (Salmon and Wyneken, 1987; Pilcher et al., 2000). This initial phase lasts for approximately 24 hours (Wyneken and Salmon, 1992) and is characterized by frenzied swimming, which facilitates the rapid movement of hatchlings away from shallow nearshore areas (Wyneken, 2000). Factors which confound or delay the completion of this phase may significantly increase hatchling mortality (Whelan and Wyneken, 2007).
Hatchlings that do succeed in reaching the sea after suffering a period of misorientation have been shown to be compromised in their initial swim offshore. Lorne and Salmon (2007) noted that hatchlings that have completed seaward crawls were able to orient away from shore in the absences of wave cues; whereas those placed in the sea after two hours of misorientation were unable to do so. Furthermore, hatchling activites and swim speed are known to decrease with retention time after emergence (Pilcher and Enderby, 2001).
Taking all these circumstances into account, it is consequently of utmost importance to make every hatchlings entering the sea count. These hatchlings have to be as healthy as possible and given the best chance to survive the long swim ahead. Otherwise, the hatchlings will always have tougher chance of reaching adulthood.
1.2 Justification of Study
There are three incubation methods for turtle sanctuaries in the east coast of Peninsular Malaysia. Turtle Sanctuary in Cherating, which is managed by the Department of Fisheries (DOF) of Pahang, is practicing the Styrofoam box and ex-situ hatchery method for incubation. However, Styrofoam box is not the main choice since they only practice this method due to the challenges in conducting the ex-situ hatchery. For example, in early 2009, the hatchery was still under renovation, resulting in the use of Styrofoam box as an alternative. Different situations faced in Geliga, Kemaman, DOF Terengganu had to use Styrofoam box due to the insufficient fund to manage the hatchery. In the meantime, Sea Turtle Research Unit (SEATRU) of Universiti Malaysia Terengganu (UMT) practicing in-situ programme since 1993 for the eggs incubated in Chagar Hutang Santuary at Pulau Redang, Terengganu.
Eggs incubated under these different methods are differed in their incubation periods. It is obviously shown those nests incubated in-situ with the incubation periods ranges from 45 to 60 days. Whereas the incubation periods for Styrofoam box shown shorter period (ranges from 48 to 49 days) than ex-situ hatchery practice (ranges from 52 to 55 days). Though there are various methods practiced by the sanctuary management, the performance of hatchlings remains in doubt.
Even though the green turtle (Chelonia mydas) is classified as an endangered species, more than half a million of hatchlings were released to the sea annually from turtle sanctuaries in Malaysia (DOF, 2009). It would be a waste to release thousands of hatchlings when there is no contribution to the turtle population in the near future.
Early swimming and crawling performance has been chosen to evaluate the performance of the hatchlings primarily because the initial part of their migration occur in Malaysian waters, which is significant to the performance of these newly hatchlings.
The purpose of this study has been focused by the following objectives:
i. to assess the morphological characteristics of hatchlings produced by different incubation methods;
ii. to compare swimming performance and crawling speed of green turtle hatchlings incubated on in-situ and ex-situ programme;
iii. to determine the relationship between incubation methods with green turtle hatchlings' performance; and
iv. to determine the relationship between morphological characteristics of hatchlings with hatchlings' performance.
1.4 Research Concept
In general, there are two methods in incubation practices for sea turtle eggs in Malaysia. The first method is in-situ method where the nest will be marked and leave as natural incubation after nesting by the mother turtle. No matter where the location is (i.e. shaded area or open area), the nest will be left undisturbed until the eggs hatched. Immediately after the eggs hatched, hatchlings from in-situ nests will crawl by their own towards the water line.
Compared with the in-situ method, the remaining methods involved the relocation of the egg clutch after nesting activity. This method usually applies for some circumstances to protect the eggs. Relocation of these eggs will be done immediately after nesting activity in order to increase the hatching success. The eggs will then be replanted in ex-situ hatchery or in the Styrofoam boxes. Hatchlings produced from both methods need to be collected by sanctuary staff, and then be released together at certain point on the nesting beach.
The purpose of this study is to evaluate the performance of these hatchlings as an indicator to the healthiness during their early swim right after they have hatched produced by the three different incubation methods. Reptilians are commonly known that their performance and energetic behaviour are environment temperature dependent. Hence, all of the tests were conducted at the same ambient temperature. Relationship determination act to define the factor of the differences among the hatchlings' performance; whether due to the morphological characteristics or their incubation method.
This study is based on the theory that different incubation methods will produce hatchlings with different performances. On the other hand, this study aims to determine which method produces high performance hatchlings. In addition, this study focus on which incubation methods results in hatchlings to eventually have high survival rate after the early swim crossing the predator rich nearshore waters.