Study

Post-emergence handling of green turtle hatchlings: Improving hatchery management worldwide

  • Published source details Van de Merwe J.P., Ibrahim K. & Whittier J.M. (2013) Post-emergence handling of green turtle hatchlings: Improving hatchery management worldwide. Animal Conservation, 16, 316-323.

Actions

This study is summarised as evidence for the following.

Action Category

Use low intensity lighting

Action Link
Reptile Conservation

Relocate nests/eggs to a hatchery: Sea turtles

Action Link
Reptile Conservation

Relocate nests/eggs to a hatchery: Sea turtles

Action Link
Reptile Conservation
  1. Use low intensity lighting

    A replicated, site comparison study in 2005 on a sandy beach on the east coast of Terengganu, Peninsular Malaysia (van de Merwe et al. 2013) found that green turtle Chelonia mydas hatchlings from a hatchery released in low and moderate ambient artificial light took a more direct route to the sea than hatchlings released in high ambient artificial light. Green turtle hatchlings released in low and moderate artificial ambient light dispersed at an angle similar to a direct line towards to the sea (62–76° dispersal angle), while hatchlings released in high ambient light dispersed at a different angle to the most direct route (148° dispersal angle, see original paper for information about directionality). In July–October 2005, sea-finding behaviours were tested on 30 hatchlings from each of 14 hatchery nests (420 hatchlings) under three different ambient lighting scenarios–high ambient light (300 m north of hatchery), moderate ambient light (directly in front of hatchery) and low ambient light (500 m south of hatchery; 10 hatchlings/nest/lighting scenario). All trials were conducted in an 8m wide circular sand arena 20 m from the sea with hatchlings placed under a bucket in the centre before release. The angle of dispersal for each hatchling was calculated using a compass from the centre to the point where the hatchling exited the arena and compared to the angle of the direct route to the sea.

    (Summarised by: Maggie Watson, Katie Sainsbury)

  2. Relocate nests/eggs to a hatchery: Sea turtles

    A replicated, randomized study in 2004 on a sandy beach in Terengganu, Peninsular Malaysia (van de Merwe et al 2013) found that green turtle Chelonia mydas hatchlings from hatcheries released immediately after emerging moved almost twice as fast and had better body condition than hatchlings that were held for 3–6 hours prior to release. Green turtle hatchling running speeds were higher when released immediately (0.12 m/s) compared to when they were held in the hatchery for 1 h (0.11 m/s), 3 h (0.8 m/s), or 6 h (0.7 m/s) before release. Hatchling body condition was similar for newly emerged hatchlings (4.67 g/mm) and hatchlings held for 1 h (4.66 g/mm), but lower for those held for 3 h (4.61 g/mm) or 6 h (4.55 g/mm). In July–October 2004, two hundred hatchlings from 10 hatchery nests (20 hatchlings/nest) were measured for running speed (time to run over a 1.6 m plastic gutter lined with sand, repeated three times/hatchling; see original paper for details) and body condition (ratio of hatchling mass to body length). Hatchlings were measured immediately following emergence or at 1 h, 3 h and 6 h following emergence (5 hatchlings/nest/time held).

    (Summarised by: Katie Sainsbury)

  3. Relocate nests/eggs to a hatchery: Sea turtles

    A replicated study in 2004 on a sandy beach in Terengganu, Peninsular Malaysia (van de Merwe et al 2013) found that green turtle Chelonia mydas hatchlings excavated from hatchery nests immediately after most hatchlings in the nest emerged moved faster and had higher body condition than hatchlings excavated five days after most hatchlings emerged. Hatchlings excavated from nests immediately after the main clutch emergence (0.10 m/s) were faster than hatchlings excavated five days later (0.60 m/s) and had similar running speeds compared to hatchlings that emerged naturally within five days of the main emergence (0.11 m/s). Hatchlings that emerged with the main emergence were the fastest (0.12 m/s). Body condition of hatchlings excavated immediately (4.73 g/mm) was greater than hatchlings that were excavated five days later (4.39 g/mm) or that emerged naturally within five days (4.60 g/mm), and was similar to hatchlings from the main emergence (4.70 g/mm). In July–October 2004, hatchling running speed (time to run over a 1.6 m plastic gutter lined with sand, repeated three times/hatchling; see original paper for details) and body condition (ratio of hatchling mass to body length) was compared between hatchlings excavated immediately after the main emergence (124 live hatchlings from 19 nests); hatchlings excavated five days after main emergence (56 live hatchlings from 13 nests); hatchlings that emerged naturally within five days of the main emergence (16 hatchlings from 6 nests); and hatchlings from the main emergence (200 hatchlings, number of nests not provided). Up to 10 hatchlings were measured/category/nest.

    (Summarised by: Katie Sainsbury)

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