THE USE OF SEA TURTLE HATCHERIES AS AN EX SITU-CONSERVATION STRATEGY IN INDIA

ANDREA D PHILLOTT1# AND NUPUR KALE2

1 FLAME University, Pune, Maharashtra, India

2Dakshin Foundation, Bengaluru, Karnataka, India

#andrea.phillott@flame.edu.in

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Introduction

India is home to regionally important nesting populations of green (Chelonia mydas), leatherback (Dermochelys coriacea), and olive ridley (Lepidochelys olivacea) turtles. The Wildlife (Protection) Act of 1972 protects nesting sea turtles, their eggs, and hatchlings. However, there has been significant consumption of turtles and eggs, in addition to threats from predators and coastal development (as described below) over time. Hatcheries have been employed as an ex situ conservation strategy in India to mitigate such threats since at least 1973 and 1974 (Valliappan & Whitaker, 1974; Biswas et al., 1977 in Pandav et al., 2006), but details of their specific operations are sparse. Partially filling this knowledge gap are narrative accounts of sea turtle hatchery operations in India presented by Shanker & Kutty (2005) and Shanker (2015) and this paper, which compiles all available records of sea turtle hatcheries in India to infer their potential use as a conservation strategy from proportion of known nests protected and hatching success.

Methods

We searched the databases Scopus, Google Scholar and JSTOR, the Sea Turtles of India bibliography (https://www.seaturtlesofindia.org/library/bibliography/), and professional newsletters Indian Ocean Turtle Newsletter and Marine Turtle Newsletter for publications and reports on sea turtle hatcheries operating in Indian states and territories at any time to late 2017. More hatcheries may have been in operation than those described in these sources, as the news media (for example, Arockiaraj, 2017) name hatcheries at locations not described in published literature or reports. However, we chose not to include hatcheries described in news stories due to questions about the reliability of location, number of nests or eggs protected, and/or number of hatchlings released.

Results

Threats to sea turtle nests and eggs that contributed to the use of an ex situ conservation strategy and the details available for hatchery operations are summarised below (in alphabetical order by location; Tables 1-8). As many records overlap in geographic area, time, and data sets, it is not possible to quantify the number of hatcheries but the use and productivity of hatcheries as an ex situ conservation strategy may be inferred.

Andaman and Nicobar Islands

There is little publicly available information about hatcheries operating in the Andaman and Nicobar Islands. Andrews et al. (2001) describe hatcheries to which green, hawksbill, and leatherback turtle nests of unknown numbers were relocated in the decade prior to their study commencing in the 2000/01 nesting season: Ramanagar Beach (North Andaman), Smith Island (North Andaman), Cuthbert Bay (Middle Andaman Island), Rutland Island (South Andaman), and Galathea Beach (Great Nicobar Island). However, relocation of nests to hatcheries at Smith Island and Cuthbert Bay ceased in the 2000/01 nesting season due to concern about the low hatching success (30-45%) when compared with in situ nests (80-100%). In 2001/02, hatchery practices at Galathea Beach were modified (further information not provided) so that hatching success rose to 75-100% from that previously recorded (25-35%) (Andrews et al., 2001). Nests laid below the high tide line at Galathea Beach continued to be relocated to the hatchery in 2003/04 and 2004/05 nesting seasons (Andrews et al., 2006). A paper by Jadeja et al. (2016) indicates the ongoing operations of a hatchery at Galathea Bay after the 2004 Indian Ocean tsunami.

Threats to sea turtle eggs and hatchlings in the region include human consumption (note: indigenous peoples of the Andaman and Nicobar Islands are exempt from the Wildlife (Protection) Act) and predation by water monitors, feral dogs and pigs. Andrews et al. (2001) estimated that feral dogs depredated >70% of eggs and hatchlings at some locations, with pigs destroying an additional 10% of nests and consuming emerging leatherback hatchlings.

Andhra Pradesh

Andhra Pradesh (AP) supports sporadically high numbers (up to ~10,000 per season) of olive ridley turtles, but as solitary nesting events and not the mass nesting arribadas that occur in the adjacent state of Odisha. Described threats to sea turtle nests and hatchlings in AP include human consumption of eggs, depredation by feral dogs, pigs, foxes, hyenas, and jackals, light pollution, and aquaculture development (Rao, 1985; Tripathy, 2001; Tripathy et al., 2006, Saravanan et al., 2013).

Hatcheries from different areas were identified from literature about sea turtles in AP (Table 1). There is little information available about the hatchery in East Godavari District, but reports indicate that ex situ conservation of turtle nests in Visakhapatnam district commenced in 2010/11, after which all possible nests were relocated to hatcheries. The number and location of hatcheries has since varied from year to year (VSPCA, 2011, 2012, 2013, 2015, 2016, 2017) and hatching success is high (usually >80%) when compared with that of hatcheries in other locations.

Table 1. Records of olive ridley nests relocated to sea turtle hatcheries in Andhra Pradesh. Numbers of nests, eggs, hatchlings, and hatching success may not be representative of the entire nesting seasons indicated. ‘-’ indicates no information reported. An.- annually. Av.- Average.

Location Nesting Season/s # Nests &/or # Eggs Hatching Success (HS) &/or # Hatchlings Source
East Godavari district, Sacramento Island 2010/11 Saravanan et al., 2013
Visakhapatnam district, Srikakulam and Visakhapatnam 2010/11 54 nests; 5,832 eggs Av. HS 84% VSPCA, 2011
Visakhapatnam district, Bheemli, Jodugullapalem, Rushikonda & Visakhapatnam 2011/12 181 nests; 21,343 eggs Av. HS 63% VSPCA, 2012
Visakhapatnam district, Jodigullapalem and Yoga Village 2012/13 74,586 eggs Av. HS 87% VSPCA, 2013
Visakhapatnam district, Jodigullapalem and RK Beach 2014/15 320 nests; 38,793 eggs Av. HS 86% VSPCA, 2015; VSPCA, 2016
2015/16 343 nests; 39,604 eggs Av. HS 83%
Visakhapatnam district, Jodigullapalem, Lumbini Park, Peddanagaya palem, RK Beach & Tanthidi 2016/17 705 nests; 78,494 eggs Av. HS 83% VSPCA, 2017

*Hatching success in 2011/12 was potentially reduced due to inundation of the hatcheries after a tsunami and extreme high tides in March 2012, resulting from the 2012 earthquakes near Indonesia

Goa

Nests and hatchlings in Goa may be threatened by human consumption of eggs, light pollution, construction of hotels and resorts, sand mining and non-biodegradable waste on nesting beaches (Giri & Chaturvedi, 2006; Giri et al., 2006). Hatcheries in Goa (Table 2) appear to protect all nests laid on those, and some from adjacent, beaches (Giri & Chaturvedi, 2006; Giri et al., 2006). The reported hatching success is high (>~75%) in comparison to other locations.

Table 2. Records of olive ridley nests relocated to sea turtle hatcheries in Goa. Numbers of nests, eggs, hatchlings, and hatching success may not be representative of the entire nesting seasons indicated. ‘-’ indicates no information reported. Av.- average.

Location Nesting Season/s # Nests &/or# Eggs Hatching Success (HS) &/or # Hatchlings Sources
Agonda 2000/01 9 nests Av. HS 94% Giri & Chaturvedi, 2006; Giri et al., 2006
2003/04 6 nests
Galgibaga 1999/2000 10 nests Av. HS 80% Giri & Chaturvedi, 2006; Giri et al., 2006
2000/01 33 nests Av. HS 75%
2001/02 19 nests
2002/03 14 nests
Gujarat

Green and olive ridley turtles nest on the Gujarat coast, and nests may be relocated to hatcheries in the state to mitigate threats from human consumption of eggs, depredation by domestic dogs, wild pigs, monitor lizards, hyenas and jackals, and pollution such as oil, industrial effluent, sewage, and debris (Sunderraj et al., 2006a). Many of the known nests on monitored beaches in Gujarat are protected in hatcheries (see Sunderraj et al., 2006; Goswamy et al., 2013) but large number of nests will also remain in situ. Hatching success of nests relocated to hatcheries ranges from ~20-90% (Table 3; note the record of leatherback eggs also).

Table 3. Records of nests relocated to sea turtle hatcheries in Gujarat. Locations have been adjusted to their current name. Numbers of nests, eggs, hatchlings, and hatching success may not be representative of the entire nesting seasons indicated. ‘-’ indicates no information reported. An.- annually. Av.- Average.

Location/(District, Beach/Village) Turtles Nesting Season/s # Nests &/or # Eggs Hatching Success (HS) &/or # Hatchlings Source
Bhavnagar district, Hathab Green, olive ridley 1987/88-1989/90 10,689 eggs Av. HS 65% Sunderraj et al., 2002
Bhavnagar district, Piram Is. Green, olive ridley 1987/88-1989/90 40,195 eggs Av. HS 69% Sunderraj et al., 2002
Junagadh coast Green, olive ridley 2004/05-2010/11 371 nests, 31,507 eggs Av. HS 84% Sunderraj et al., 2013
Junagadh district, Kodinar Green 2004/05 4,170 eggs Av. HS 80% Goswamy et al., 2013
2006/07 2,982 eggs Av. HS 76%
2008/09-2010/11 20, 847 eggs Av. HS 21%
Junagadh district, Mangrol (inland) Visited in 1987 Frazier, 1987
Junagadh district, Sapur Beach (inland) Visited in 1987 Frazier, 1987
Junagadh district, Madhavpur Green, olive ridley 1993/94-1996/97 49,161 hatchlings Frazier, 1987; Sunderraj et al., 2001, 2002, 2013
1998/99-1999/2000 98,005 hatchlings
2005/06-2011/12 34,915 eggs Av. HS 81%
Kachchh district Olive ridley 2000 (?) 37 nests Sunderraj et al., 2001
Kachchh district, Mandvi Olive ridley 1990/91-1992/93 6,700 eggs Av. HS 64% Sunderraj et al., 2002, 2006b, 2013; Meena et al., 2007, 2009
Olive ridley 1999/2000 37 nests, 4,395 eggs
Green, olive ridley 2000/01 4,399 eggs Av. HS 41%
Olive ridley 2001/02 1,273 eggs Av. HS 32%
Olive ridley 2004/05-2005/06 2,002 eggs Av. HS 59%
2006/07-2007/08 1,491 eggs Av. HS 68%
Green 2007/8-2011/12 69 nests, 7,752 eggs Av. HS 79%
Kachchh district, Nalia Olive ridley 1985/86-1986/87 199 eggs Av. HS 72% Meena et al., 2007
Olive ridley, leatherback 2000/01 321 eggs Av. HS 48%
Olive ridley 2001/02 210 eggs Av. HS 66%
Olive ridley 2004/05 533 eggs Av. HS 69%
Green 2005/06 135 eggs Av. HS 53%
Kachchh district, Nana-Layja 2005/06 108 eggs Av. HS 60% Meena et al., 2007
Porbander district, Positra Green 2010/11 13 nests Goswamy et al., 2013
Porbander district, Rangbai Green 2004/05 82 nests, 8,188 eggs Av. HS 73% Sunderraj et al., 2006b, 2013
Olive ridley 2004/05 23 nests, 2,514 eggs Av. HS 767%
Green, olive ridley 2007/08-2011/12 96 nests, 9,080 eggs Av. HS 86%
Porbander district, Tukda Miyani Green 2004/05 45 nests, 4,545 eggs Av. HS 71% Sunderraj et al., 2006b
Olive ridley 2004/05 24 nests, 2,425 eggs Av. HS 69%
Karnataka

Olive ridley turtles (and potentially greens or leatherbacks- see Sharath, 2006) nest sporadically in Karnataka. Hatcheries in the state (Table 4) may operate for short periods of time (as little as a year) and protect low numbers of nests annually (K. Shanker and M. Manoharakrishnan, pers.comm.). Threats to nests and hatchlings include human consumption of eggs, light pollution, depredation by domestic and feral dogs, and beach erosion and loss due to the construction of seawalls (see Sharath, 2006). Nest counts for Dakshina Kannada, Udupi, and Uttara Kannada districts (Sharath, 2006; Pandit & Soans, 2013) suggest that all known nests may be relocated to hatcheries, where the average hatching success varies between ~15-97% (Table 4).

Table 4. Records of olive ridley turtle nests relocated to hatcheries in Karnataka. Locations have been adjusted to their current name. Numbers of nests, eggs, hatchlings, and hatching success may not be representative of the entire nesting seasons indicated. ‘-’ indicates no information reported. Av.- average.

Location/(District, Beach/Village) Nesting Season/s # Nests &/or # Eggs Hatching Success (HS) &/or # Hatchlings Source
Karnataka coast, 40 unnamed locations 1984 Appayya,1985 (in Sharath, 2006); Anonymous, 2011
Karnataka coast, 3 unnamed locations 1985? 15,000 hatchlings
Dakshina Kannada district, Baindur 1985/86 Frazier, 1989
Dakshina Kannada district, Thrasi 1984/85-1986/87 89 nests Range HS 20-94% Frazier, 1989
Udupi district, Unnamed location 2004-2006 2,348 eggs Av. HS 76% McCann, 2007
Udupi district, Bengre Beach 1984/85 2,560 hatchlings Madhyastha et al., 1986 (in Sharath, 2006); Frazier, 1989
1986/87 1,612 eggs Av. HS 90%
Uttara Kannada district, 3 locations 2005/06 >5,000 hatchlings Pandit & Soans, 2013
2007/08-2010/11 186 nests
Uttara Kannada district, Apsarakonda 2006/07 9 nests, 846 eggs Pandit, 2008; Chandran et al., 2012
2007/08-2008/09 1,617 eggs Av. HS 53%
Uttara Kannada district, Devbag 2001/02 616 eggs Av. HS 16% Kurian & Nayak, 2003
Uttara Kannada district, Dhareshwara 2006/07 6 nests, 704 eggs Pandit, 2008; Anonymous, 2011; Chandran et al., 2012
2007/08-2008/09 4,739 eggs Av. HS 41%
Uttara Kannada district, Gangavali 1985/86 Frazier, 1989; Pandit, 2008; Anonymous, 2011; Chandran et al., 2012
2006/07 8 nests, 677 eggs
2007/08-2008/09 1,959 eggs Av. HS 48%
Uttar Kannada district, Haldipur 1985/86 Frazier, 1989; Anonymous, 2011; Chandran et al., 2012
2006/07
2007/08-2008/09 28 nests, 2,845 eggs Av. HS 43%
Uttara Kannada district, Heeregutti 2004-2006 Total 2,500 hatchlings Pandit & Soans, 2013
Uttara Kannada district, Holadgadde Beach 1985/86 Frazier, 1989
Uttara Kannada district, Hosahitlu (Manki) 2007/08-2008/09 10 nests, 897 eggs Av. HS 60% Chandran et al., 2012
Uttara Kannada district, Jali Village 1985/86-1986/87 69 nests Frazier, 1989
Uttara Kannada district, Kade Beach 1985/86 Frazier, 1989
Uttara Kannada district, Kadle (Holangadde) 2006/07 7 nests, 712 eggs Pandit, 2008; Anonymous, 2011; Chandran et al., 2012
2007/08 1,802 eggs Av. HS 50%
Uttara Kannada district, Kagal 2006/07 Anonymous, 2011a; Chandran et al., 2012
2007/08-2008/09 3 nests, 278 eggs Av. HS 97%
Uttara Kannada district, Kasarkod Beach 1985/86 Frazier, 1989
Uttara Kannada district, Kodibag Beach Est. 2003 Pandit & Soanes, 2013
Uttara Kannada district, Manki 2006/07 Anonymous, 2011
Kerala

Olive ridley eggs and hatchlings in Kerala experience similar threats to those elsewhere in India: human consumption of eggs (Dileepkumar & Jayakumar, 2006; Bhupathy, 2007), depredation by feral dogs and jackals (Damodar, 2002), light pollution, and beach erosion and loss due to the construction of seawalls (Pareparambil & Mathew, 2013). We identified sea turtle hatcheries from publications and reports, with ~30-90% of eggs successfully hatching (Table 5). Only a fraction of the coast is monitored (e.g. only 8km of beach on the 71km of coastline Kozhikode district is monitored (Pareparambil & Mathew, 2013) but likely represents the limited nesting habitat available due to the extensive construction of sea walls (Dileepkumar & Jayakumar, 2006).

Table 5. Records of olive ridley nests relocated to sea turtle hatcheries in Kerala. Locations have been adjusted to their current name. Numbers of nests, eggs, hatchlings, and hatching success may not be representative of the entire nesting seasons indicated. ‘-’ indicates no information reported. An.- annually. Av.- Average.

Location/(District, Beach/Village) Nesting Season/s # Nests &/or # Eggs Hatching Success (HS) &/or # Hatchlings Source
Calicut district, Kolavi & Kasaragod district, Thaikadappuram 2002/03-2006/07 104 nests, 13,314 eggs Av. HS 75% Kumar, 2007
Kozhikode district, Kolavipalam
Kasaragod district, Thaikadappuram 2002/03-2013/14 >151 nests Av. HS 74% Laladhas et al., 2017
Kozhikode district, Kolavipalam 1996 onwards An. 40-60 nests Kutty, 2001; Bhupathy et al., 2006; Bhupathy, 2007; Laladhas et al., 2017
1998-2012/13 450 nests, 44,006 eggs Av. HS 80%
1998/99-2015/16 Range 322-6,264 eggs Range HS 33-89%
Thrissur district, Palapetty beach 2015/16 Sreeram et al., 2016
Maharashtra

The number of nests protected over time at hatcheries in Maharashtra is relatively low (see Table 6), reflecting the low numbers of nesting olive ridley and, sporadically, green turtles in the state (Giri & Chaturvedi, 2006). Katdare (2013) reported that all known nests on monitored beaches are transferred to hatcheries, with the average hatching success around 50% (Table 6). Conservation of sea turtle nests in hatcheries occurs to mitigate threats from human consumption of eggs, chemical pollution, and sewage (Giri & Chaturvedi, 2006).

Table 6. Records of olive ridley nests relocated to sea turtle hatcheries in Maharashtra. Locations have been adjusted to their current name. Numbers of nests, eggs, hatchlings, and hatching success may not be representative of the entire nesting seasons indicated. ‘-’ indicates no information reported. Av.- Average.

Location/(District, Beach/Village) Nesting Season/s # Nests &/or # Eggs Hatching Success (HS) &/or # Hatchlings Source
Raigad district, Akshi To 2008 1 nest Sanaye & Katdare, 2009
Raigad district, Diveagar 2004/05 4 nests 237 hatchlings Giri et al., 2006; Sanaye & Katdare, 2009; Katdare, 2012
To 2008 22 nests
2011/12 6 nests
Raigad district, Harihareshwar 2004/05 4 nests, 455 eggs Av. HS 56% Giri et al., 2006; Sanaye & Katdare, 2009; Katdare, 2012
2005/06 4 nests
2011/12 6 nests
Raigad district, Maral To 2008 8 nests Sanaye & Katdare, 2009; Katdare, 2012
2011/12 8 nests
Raigad district, Murud Harnai To 2008 3 nests Sanaye & Katdare, 2009
Raigad district, Murud Janjira 2005/06 1 nest Sanaye & Katdare, 2009
Ratnagiri district, 5 unnamed locations 2002/02-2006/07 214 nests >9,000 hatchlings Katdare, 2008
Ratnagiri district, Anjarle To 2008 10 nests Sanaye & Katdare, 2009; Katdare, 2012
2011/12 1 nest
Ratnagiri district, Dabhol 2004/05 4 nests, 410 eggs Av. HS 57% Giri et al., 2006; Sanaye & Katdare, 2009; Katdare, 2012
To 2008 23 nests
2011/12 2 nests
Ratnagiri district, Guhagar 2011/12 4 nests Katdare, 2012
Ratnagiri district, Kelshi 2004/05 1 nest, 51 eggs Av. HS 28% Giri et al., 2006; Sanaye & Katdare, 2009; Katdare, 2012
To 2008 9 nests
2011/12 1 nest
Ratnagiri district, Kolthare 2004/05 322 eggs Av. HS 26% Giri et al., 2006; Sanaye & Katdare, 2009; Katdare, 2012
To 2008 21 nests
2011/12 5 nests
Ratnagiri district, Sandkhol 2005/06 1 nest Sanaye & Katdare, 2009
Ratnagiri district, Tavsal 2011/12 2 nests Katdare, 2012
Ratnagiri district, Velas 2002/03-2004/05 94 nests, 9,868 eggs Av. HS 50% Katdare & Mone, 2003; Giri et al., 2006; Katdare, 2012
2011/12 15 nests
Sindhudurg district, 5-11 unnamed locations 2007/08-2013/14 7,343 eggs Av. HS 54% Andhare & Hatkar, 2015
Sindhudurg district, Bhogave, Katvan, Mochemad, Shiroda, Tambaldeg, Tarkarli, Vayangani To 2008 10 nests Sanaye & Katdare, 2009; Sanaye & Pawar, 2009
Odisha

Olive ridley turtle arribadas or mass nesting events have been reported from three beaches in Odisha, Devi River mouth, Gahirmatha and Rushikulya, while much of the rest of the state’s coastline supports solitary nesting turtles of the same species (see Pandav et al., 2006; Kar & Peters, 2013). As the mass nesting events may exceed 1 lakh (i.e. 100,000) individual turtles annually, only a small proportion of the nests laid in Odisha each year are likely to be relocated to a hatchery. We found records of hatcheries in four districts, but only one specific location (Table 7). Limited information about hatching success is available, but suggests that a high proportion (>90%) of relocated eggs hatched in two years of study.

Table 7. Records of olive ridley nests relocated to sea turtle hatcheries in Odisha. Numbers of nests, eggs, hatchlings, and hatching success may not be representative of the entire nesting seasons indicated. ‘-’ indicates no information reported. An.- annually. Av.- Average.

Location Nesting Season/s # Nests &/or # Eggs Hatching Success (HS) &/or # Hatchlings Source
Ganjam district, Ramayapatana 2012/13 195 nests Av. HS 95% Behera & Kar, 2013
Ganjam district, Rushikulya hatchery* 2009-16 ~30 nests Av. HS 63% Chandarana et al., 2017
Jagatsinghpur district Kar & Peters, 2013
Kendrapara district Kar & Peters, 2013
Puri district Kar & Peters, 2013

*nests collected from Purunabandha, Gokharkuda and Podampetta beaches

Tamil Nadu

Only olive ridley turtles (but possibly also leatherbacks; Arockiaraj, 2017) have been reported nesting in Tamil Nadu in recent years (see Saravanan et al., 2013), and nests and hatchlings are vulnerable to human consumption of eggs (>95% of nests; Bhupathy & Saravanan, 2006) which may be collected by professional poachers, and depredation by jackals and domestic dogs (Bhupathy et al., 2006). Hatcheries (Table 8) have been used during the 45 years of near continuous monitoring and protection of nests on beaches adjacent to Chennai by the Madras Snake Park Trust, Central Marine Fisheries Research Institute, Tamil Nadu Forest Department, and Students’ Sea Turtle Conservation Network. Many of the known nests laid on Besant Nagar and Marina beaches are relocated to hatcheries (see Shanker, 2003; Arun, 2011; Arun, 2013), and a comparison of annual numbers of nests on monitored beaches in Nagapattinam (17 nests in 2003/04, 30 nests in 2004/05, and 37 nests in 2011/12- Saravanan et al., 2013) with the number of nests relocated to hatcheries in the district (Table 8) suggests the same situation. The reported hatching success varies among hatcheries, from ~33%-93%.

Table 8. Records of olive ridley nests relocated to sea turtle hatcheries in Tamil Nadu. Numbers of nests, eggs, hatchlings, and hatching success may not be representative of the entire nesting season/s indicated. ‘-’ indicates no information reported. An.- annually. Av.- Average.

Location/(District, Beach/Village) Nesting Season/s # Nests &/or # Eggs Hatching Success (HS) &/or # Hatchlings Source
Chennai district, Adyar River to 30km south 1988/89-1991/92 504 nests, 59, 472 eggs Av. HS 66% Shanker,1994
Chennai district, Besant Nagar & Marina Beaches 1989-2011 134 nests 43,106 hatchlings Shanker, 2003; Arun, 2011; Arun, 2013
2013 285 nests 22,000 hatchlings
Chennai district, Injambakkam 44 nests Anonymous, 1982; Dharini, 2007
2007 1 nest, 100 eggs Av. HS 93%
Chennai district, Kovalam 1978-1983 1,014 nests Av. HS 33% Silas & Rajagopalan, 1984
Chennai district, Madras Snake Park Trust 1974-77 197 nests Bhupathy et al., 2006
Chennai district, Nainar Kuppam 2006, 2007 20 nests, 2,037 eggs Av. HS 64% Dharini, 2007
Chennai district, Nilankarai 1998-99 69 nests ~6,000 hatchlings Gopal et al., 2000
Chennai district, Panaiyur Kuppam 2006, 2007 10 nests, 1,137 eggs Av. HS 21% Dharini, 2007
Chennai district, Periya Neelankarai 2006, 2007 6 nests, 718 eggs Av. HS 72% Dharini, 2007
Chennai district, Thiruvanmiyur 1973/74 10 nests, 1,152 eggs Av. HS 73% Valliappan & Whitaker, 1974; Whitaker, 1979
1974/75-78/79 197 nests, 21,760 eggs Av. HS 60%
Nagapattinam district, Point Calimere 2000 14 nests, 1,586 eggs Av. HS 76% Baruah, 2001
Nagapattinam district, Point Calimere, Arcotthurai & Vanavan mahadevi 1982/83 30,046 eggs Av. HS 81% Rahaman et al., 1985
Nagapattinam district, Point Calimere, Vanavan mahadevi & Vizhundamavadii 1983/84 30,771 eggs Av. HS 84% Rahaman et al., 1985
Nagapattinam district, Koolaiyar, Madavamedu, Point Calimere, Tharangambadi & Vanagiri 2005/06-2008/09 14,366 eggs Av. HS 49% Velusamy & Sundararaju, 2009
Union Territory of Puducherry, Puducherry Sivakumar et al., 2016

 

West Bengal

Olive ridley turtles nest in low densities on beaches of the mainland and islands throughout the Sunderbans in West Bengal (see Bhadury et al., 2013). Threats to sea turtle nests and hatchlings include human consumption of eggs (Raut & Nandi, 1988), and depredation of ~50% of nests by animals such as water monitors and wild boar (Gani, 2000; Chowdhury et al., 2006; Bhadury et al., 2013).
Some of the early studies in India on sea turtle egg, hatchling, and incubation parameters were conducted on nests relocated to three hatcheries in West Bengal (Table 9). The most recent estimates of nest numbers in the state were 1,564 nests in the 2000/01 nesting season and 87 nests in 2001/02 (Chowdhury et al., 2006) while no nests were found during a survey late in the 2010/11 season (Bhadury et al., 2013). Therefore, it appears that a relatively low proportion of nests in West Bengal may have been relocated to hatcheries in the past. The reported hatching success is low (~10-50%), potentially due to the long-distance transport of eggs from islands (Kalash, Kanak, Mechua and Sainmari- Raut & Nandi, 1985; Chowdhury et al., 2006) to hatcheries days after oviposition. For example, Sanyal (1984) describes the transport of clutches that were 24hr and “slightly older” by boat from an unnamed island to Sajnekhali; the transport time is not described but the distance given is >100km .so the time for relocating nests is likely to exceed that recommended as a best practice (see Limpus et al., 1979; Parmenter, 1980; Mortimer, 1999; SToI, 2011).

Table 9. Records of olive ridley nests relocated to sea turtle hatcheries in the South 24 Parganas district of West Bengal. Numbers of nests, eggs, hatchlings, and hatching success may not be representative of the entire nesting season/s indicated. ‘-’ indicates no information reported. Av.- Average.

Location Nesting Season/s # Nests &/or # Eggs Hatching Success (HS) &/or # Hatchlings Source
Bhagabatpur 1983 4 nests, 600 eggs Av. HS 20% Banerjee, 1985a, b
Bhagabatpur & Sajnekhali pre. 1983 ~2,000 hatchlings Raut & Nandi, 1985; Chowdhury et al., 2006
1984-1999 ~1,000 hatchlings
2000/01 1,928 eggs Av. HS 10%
Sajnekhali 1983 3 nests, 485 eggs Av. HS 51% Sanyal, 1984

Discussion

There has been widespread use of hatcheries over time in India to protect sea turtle nests against predators and poachers and other human activities. The number and longevity of hatcheries in each state or district varies and should not be the sole indicator of conservation effort. Local factors such as nesting numbers and density, availability of resources, and involvement of volunteers may determine whether a large number of hatcheries operate for short periods at different times (e.g. hatcheries in Karnataka) or fewer hatcheries operate for decades (e.g. as seen in the Andaman and Nicobar Islands and Chennai, Tamil Nadu).
This review reveals varied rates of hatching success for nests relocated to hatcheries in India, albeit within the ranges described for hatcheries elsewhere in the region (see Phillott, 2018; Phillott et al., 2018 a, b). As the majority of nests in some states (e.g. Gujarat, Maharashtra and Karnataka) and the majority of nests on important beaches in other states (e.g. Besant Nagar in Tamil Nadu) are relocated to hatcheries, it is important to understand how the hatchling production of this ex situ conservation strategy can be optimised. The lack of detailed information about hatchery practices in the available literature does not allow us to identify specific practices (e.g. egg collection, handling, and transport techniques (see Limpus et al., 1979; Parmenter, 1980; Mortimer, 1999; SToI, 2011) that could be modified to improve hatching success. Further research will now be conducted to acquire relevant details through face to face interviews with hatchery personnel.

Acknowledgements

This work is part of a larger project examining sea turtle hatcheries in India, which was supported by a Science Grant from SWOT (The State of the World’s Sea Turtles). Much of the older literature, especially unpublished reports, were obtained through the invaluable Bibliography at Sea Turtles of India (https://www.seaturtlesofindia.org/library/bibliography/). Our thanks to Kartik Shanker and Muralidharan Manoharakrishan for their assistance in obtaining other literature and for discussions about hatcheries in India.

Literature cited:

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