BEST PRACTICES IN SEA TURTLE HATCHERY MANAGEMENT FOR SOUTH ASIA

ANDREA D PHILLOTT^1# AND KARTIK SHANKER^2,3

¹FLAME University, Pune, Maharashtra, India

²Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, India

³Dakshin Foundation, Bengaluru, India

^#andrea.phillott@flame.edu.in

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Papers in Issue 27 of the Indian Ocean Turtle Newsletter highlight the extent to which countries in South Asia use hatcheries as an ex situ conservation strategy. Hatcheries are often perceived as ‘safe’ places to incubate sea turtle nests. Depending on the hatchery location and construction, eggs may be protected from predators, poachers, tidal inundation, and beach erosion. Hatcheries may also be used to raise community awareness about the biology and need for conservation of sea turtles, and provide opportunities for community revenue through ecotourism.

However, there should be ongoing threats to eggs in the natural environment for nests to be moved to a hatchery, as there are disadvantages to this practice. Hatching success in hatchery nests may be far lower than that of natural nests on the beach if poor hatchery management practices are employed, and sex ratios of hatchlings can be skewed if the nest temperatures within a hatchery differ from those on the natural beach. Operating a hatchery following best practice guidelines requires trained personnel and sufficient resources to protect and monitor nests throughout the nesting season (Mortimer, 1999; Shanker et al., 2003).

Considering the disadvantages of incubating eggs in a hatchery, sea turtle nests should preferably remain in situ for the duration of the incubation period. Nests can be protected in their original location, for example, caged (Kurz et al., 2011) or meshed (e.g. O’Connor et al., 2017) to exclude predators, or relocated to a higher site on the beach if laid close to the high tide line (e.g. Tuttle & Rostal, 2010). Community awareness and conservation initiatives have proved successful at reducing the loss of nests to poachers (e.g. Rajakaruna et al., 2009; West, 2010),

However, if moving eggs to a hatchery will ensure a much higher hatching success than the strategies described above, then hatchery location and construction, methods of egg collection and transport, hatchery nest characteristics and density, and hatchling handling and release, should aim to maximise the number of hatchlings produced. Manuals relevant to the conservation of sea turtles in countries within the Indian Ocean and South East Asia (and globally) can be used as reference material for hatchery operations- Eckert et al. (1999), Ahmad et al. (2004) and SToI (2011). A visual summary of best practise for sea turtle hatchery management is available on the website Sea Turtles of India (https://www.seaturtlesofindia.org/library/outreach-material/). For quick reference, the best practices in hatchery management have been summarised in Table 1; references to studies that support the recommendations have also been provided.

We also recommend that hatchery managers periodically review the need for nests to be moved from their natural location, as changes in predator density and poaching activities may occur over time, removing the need for hatcheries to protect nests. Nests demonstrating a high hatching success and with a low risk of egg loss from depredation, poaching, tidal inundation, erosion, microbial invasion, etc should remain where they are laid.

Table 1. A summary of best management practices for sea turtle hatcheries.

Best Practice		Supporting Literature
Hatchery location	Choose a location at least one vertical metre above the highest high tide line and distant from tidal creeks, streams, river mouths etc to reduce risk of inundation or flooding and embryo mortality. Minimise distance between nesting beach and hatchery to reduce transport time and potential for embryo mortality. Provide a diversity of nest microhabitats (e.g. shade, slope) to reflect conditions on the nesting beach and avoid potentially skewing sex ratios of hatchlings. Change location of hatchery every year to avoid accumulation of organic material and high microbial load.	Mortimer et al. (1999), Shanker et al. (2003), Ahmad et al. (2004); Spanier (2010); Maulany et al. (2012)
Hatchery construction (incl shading)	Enclose hatchery in fence constructed of chain link, wire mesh, barbed wire, cane, bamboo or slats as available. Reinforce the base of the fence with 1-2m of 0.5cm-1.0cm mesh, buried to 50cm deep to prevent entry of burrowing predators. Minimise the risk of lethal nest temperatures, especially late in incubation, by partially shading the hatchery with a material such as shade cloth or coconut thatch, or shading individual nests with thatch baskets. Permanently shaded hatcheries should monitor their nest temperatures to reflect those of in situ nests, to avoid skewing hatchling sex ratios from natural.	Mortimer et al. (1999), Shanker et al. (2003), Ahmad et al. (2004)
Egg collection	Minimise movement and use of lights until turtle begins laying, to minimise disturbance and the risk the turtle will return to the sea without nesting. Catch eggs as they are being laid by hand or into a clean plastic bag (be careful not to disturb the turtle by touch or movement during oviposition), or mark location of nest with a length of rope or coloured tape reaching from eggs to beach surface and remove eggs once turtle has finished nesting. Do not probe for nests with a stick or other Implement, to avoid destroying eggs.	Mortimer et al. (1999), Shanker et al. (2003), Ahmad et al. (2004)
Egg handling and transport	Rebury eggs in hatchery within 2-3hr of oviposition to minimise embryo mortality. Eggs to be transported short distances more than 2hr after oviposition should be removed from the nest without vertical or horizontal rotation and egg orientation indicated by marking the top of eggs with a soft pencil. Original orientation should be maintained during transport. Transport of eggs for long distances and/or long travel times may require low-temperature or hypoxic environments to maintain embryo viability. Transport eggs in rigid containers to minimise rolling and potential embryo mortality.	Limpus et al. (1979); Parmenter (1980); Harry & Limpus (1989); Mortimer et al. (1999), Shanker et al. (2003), Ahmad et al. (2004); Williamson et al, (2017)
Reburial of nests	Rebury eggs in a location within the hatchery that mimics the natural nest environment. Dig hatchery nest to the same depth as the natural nest. Mimic the shape of natural sea turtle nests (usually flask shaped with a narrower neck than base). Place eggs Individually into the nest; do not ‘pour’ eggs from a bucket or bag. Cover the eggs with moist sand removed during nest construction; do not expose eggs to dry sand as there is a risk of desiccation. Incubate a single cutch in the same hatchery nest; do not split clutches between nests, or combine clutches from different nests.	Mortimer et al. (1999), Shanker et al. (2003), Ahmad et al. (2004); van de Merwe et al. (2006); Rusli & Booth (2016)
Nest density	Maintain a density of 1 nest/m2 to minimise the effects of adjacent nests on temperature and respiratory gas availability, and allow space for hatchery workers to move.	Mortimer et al. (1999), Shanker et al. (2003), Ahmad et al. (2004); Maulany et al. (2012)
Nest enclosures	Protect nests from predators by constructing cylindrical nest enclosures of rigid material ~60cm in diameter. (Avoid rigid wire as it can injure hatchlings.) Bury 10cm into sand for burrowing predators and cover with mesh or net for aerial predators.	Mortimer et al. (1999), Shanker et al. (2003), Ahmad et al. (2004)
Hatching release	Predict emergence date, often 45-55 days after oviposition. The characteristic ‘caving in’ of sand above the nest indicates emergence will usually begin within 2-3 days. Check enclosures every 30-60mins from afternoon to dawn and at other times when hatchlings may emerge (e.g. on overcast days and after rain) around the predicted emergence date. Release hatchlings as soon as possible to prevent exhaustion, desiccation, loss of vigour, possible injury, or death from predators. Release hatchlings in groups if possible to improve survival probability; however, early emergers should not be held until more hatchlings emerge as this practice can result in loss of vigour. Randomise clutch release sites hundreds of metres apart to avoid creating fish feeding stations off the beach, which increases the risk of predation. Allow hatchlings to crawl from the dune across the beach and enter the ocean unassisted to facilitate imprinting. Manage observers to ensure hatchlings are not injured or their progress to the sea impeded; parallel lines ~20m apart on the beach give a mark for people to stand behind while hatchlings crawl between lines. Ensure artificial lights are shielded during hatchling emergence and release, and after they enter the ocean to minimise disorientation. If hatchlings emerge in heat of day or immediate release is not possible, hold hatchlings in a soft, damp cloth or sack in cool, dark place. Do not hold hatchlings in water as they will enter their ‘swim frenzy’ period and deplete energy reserves needed for survival and dispersal.	Mortimer et al. (1999), Wyneken (2000); Pilcher & Enderby, 2001; Shanker et al. (2003), Ahmad et al. (2004); van de Merwe et al. (2013)
Hatchery records	Number each nest in the hatchery and associate with a standard data record form. Complete a data sheet or data book entry for each nest, including information such as date of oviposition, clutch size, date of emergence, number of hatchlings, and (if recorded) SCL, weight, and scalation pattern. Collect data from emerged hatchlings restrained in enclosure e.g. emergence date, and hatchling straight carapace length (SCL), weight and scalation pattern if possible.	Mortimer et al. (1999), Shanker et al. (2003), Ahmad et al. (2004)
Monitoring and evaluation	Calculate incubation period as number of days between oviposition and emergence. Excavate nest 2-3 days after the majority of hatchlings have emerged and calculate: a)       Hatching Success= (Number of hatched eggs/Total number of eggs) x 100 b)       Emergence Success= (Number of naturally emerged hatchlings/Total number of eggs) x 100 Monitor nest temperature and hatchling sex ratio from a statistically valid proportion of nests in hatchery and compare with data from the natural beach/es for your population of sea turtles.	Mortimer et al. (1999), Schäuble et al. (2002); Shanker et al. (2003)
Education and awareness	Create educational materials (e.g. posters) for visitors to the hatchery to raise awareness about sea turtle biology and conservation. Encourage students and local wildlife enthusiasts to volunteer at the hatchery if possible.	Shanker et al. (2003)
Personnel	Train employees and volunteers in sea turtle biology, conservation, and hatchery management techniques. Provide access to general articles and manuals about sea turtle biology and hatchery practices. Run or co-manage the hatchery with the local community when possible. Collaborate with other community programmes in same area or elsewhere on the coast when possible.	Shanker et al. (2003)

Literature cited:

Ahmad, A., T. Zulkifli, M.I. Mahyam, A.R. Solahuddin & Z. Nor Azman. 2004. A Guide to Set-Up and Manage Sea Turtle Hatcheries in the Southeast Asian Region. Marine Fisheries Resources Development and Management Department and Southeast Asian Fisheries Development Center (SEAFDEC).

Harry, J.L. & C.J. Limpus. 1989. Low-temperature protection of marine turtle eggs during long-distance relocation. Australian Wildlife Research 16: 317-320.

Limpus, C.J., V. Baker & J.D. Miller. 1979. Movement induced mortality of loggerhead eggs. Herpetologica 35: 335-338.

Maulany, R.I., D.T. Booth & G.S. Baxter. 2012. The effect of incubation temperature on hatchling quality in the olive ridley turtle, Lepidochelys olivacea, from AlasPurwo National Park, East Java, Indonesia: Implications for hatchery management. Marine Biology 159: 2651–2661.

Mortimer J.A. 1999. Reducing threats to eggs and hatchlings: Hatcheries. In: Research and Management Techniques for the Conservation of Sea Turtles (eds. Eckert, K.L., K.A. Bjorndal, F.A. Abreu-Grobois & M. Donnelly). Pp 175-178. IUCN/SSC Marine Turtle Specialist Group Publication No. 4.

O’Connor, J.M., C.J. Limpus, K.M. Hofmeister, B.L. Allen & S.E. Burnett. 2017. Anti-predator meshing may provide greater protection for sea turtle nests than predator removal. PloS ONE 12: e0171831.

Parmenter, C.J. 1980. Incubation of the eggs of the green sea turtle, Chelonia mydas, in Torres Strait, Australia: The effect of movement on hatchability. Australian Wildlife Research 7: 487-91.

Pilcher, N.J. & S. Enderby. 2001. Effects of prolonged retention in hatcheries on green turtle (Chelonia mydas) hatchling swimming speed and survival. Journal of Herpetology 35: 633-663.

Rajakaruna, R.S., D.M.Naveen, J. Dissanayake, E.M.L. Ekanayake & K.B. Ranawana. 2009. Sea turtle conservation in Sri Lanka: Assessment of knowledge, attitude and prevalence of consumptive use of turtle products among coastal communities. Indian Ocean Turtle Newsletter 10: 1-13.

Rusli, M.U. & D.T. Booth. 2016. Bigger clutch sizes save offspring energy during nest escapes. Behavioral Ecology and Sociobiology 70: 607-616.

Schäuble, C., K. Ibrahim, A.R. Kassim, M. Hamann, & J. Whittier. 2002. Monitoring hatchery success– What’s worthwhile? In: Proceedings of the 22nd Annual Symposium on Sea Turtle Biology and Conservation. (comp. Seminoff, J.A.). NOAA Technical Memorandum NMFS-SEFSC-503, 308 p.

Sea Turtles of India (SToI). 2011. A Comprehensive Field Guide to Research, Monitoring and Conservation (comps. Shenoy, S., T. Berlie & K. Shanker). Dakshin Foundation, Bangalore and Madras Crocodile Bank Trust, Mamallapuram, India. Pp. 148.

Shanker, K., B.C. Choudhury & H.V. Andrews. 2003. Sea Turtle Conservation: Beach Management and Hatchery Programmes. A GOI-UNDP Project Manual. Centre for Herpetology/Madras Crocodile Bank Trust, Mamallapuram, Tamil Nadu, India.

Spanier, M.J. 2010. Beach erosion and nest site selection by the leatherback turtle Dermochelys coriacea (Testudines: Dermochelyidae) and implications for management practices at Playa Gandoca, Costa Rica. Revista de Biología Tropica 58: 1237-1246.

Tuttle, J. & D. Rostal. 2010. Effects of nest relocation on nest temperature and embryonic development of loggerhead sea turtles (Caretta caretta). Chelonian Conservation and Biology 9: 1-7.

van de Merwe, J., K. Ibrahim & J. Whittier. 2006. Effects of nest depth, shading, and metabolic heating on nest temperatures in sea turtle hatcheries. Chelonian Conservation and Biology 5: 210-215.

van de Merwe, J.P., K. Ibrahim & J. M. Whittier. 2013. Post-emergence handling of green turtle hatchlings: Improving hatchery management worldwide. Animal Conservation 16: 316–323.

West, L. 2010. A multi-stakeholder approach to the challenges of turtle conservation in the United Republic of Tanzania. Indian Ocean Turtle Newsletter 11: 44-50.

Williamson S.A., R.G. Evans & R.D. Reina. 2017. When Is embryonic arrest broken in turtle eggs? Physiological and Biochemical Zoology 90: 523–532.

Wyneken, J. 2000. The migratory ehaviour of hatchling sea turtles beyond the beach. In: Sea Turtles of the Indo-Pacific. (eds. Pilcher, N.J. & G. Ismail). Pp 121–142. ASEAN Academic Press, London.