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Turtle hatcheries in Sri Lanka: Boon or bane?

By Suhashini Hewavisenthi
Five sea turtle species nest in Sri Lanka -- the green turtle (Chelonia mydas), olive ridley (Lepidochelys olivacea), leatherback (Dermochelys coriacea), hawksbill (Eretmochelys imbricata) and loggerhead (Caretta caretta). However, Sri Lanka's share of the global sea turtle treasure is declining, as clearly indicated by recent reports and observations. Exploitation of sea turtles and their eggs continues all along the coastline, year-round, despite the fact that all sea turtles and their eggs are protected by law. According to the Fauna and Flora Protection Ordinance, 1 March 1938, it is an offense "to capture, kill, injure or possess (sea turtles) or their eggs". More effective protective measures are urgently needed to reduce the near total consumption of eggs by humans, and by feral and wild animals. The best approaches are to encourage public awareness, increase enforcement, and control or intercept poachers and predators so that the eggs can hatch in situ. Enclosed beach hatcheries should be established only when these other approaches have been tried and found to be unsuccessful.
A tourist attraction
Unfortunately, the principal sea turtle nesting beaches are on the western, southwestern, and southern coasts of the island where the human population density is very high. While the loss of eggs to feral and wild animals might be controlled by enclosing in situ nests with wire mesh, protecting eggs from humans is more difficult since there are no special reserves for sea turtles. Some protection is offered to turtles in Wilpattu and Yala national parks, which include about 30 and 40 miles of coastline in the northwest and the southeast, respectively, but appeals by concerned individuals and organisations for special Sea Turtle Reserves have been ignored. Under these circumstances, hatcheries seem the only avenue to ensure the success of sea turtles in Sri Lanka and growing interest is now focused on the conservation of sea turtles by means of hatcheries. This is partly because tourists find the hatcheries an interesting attraction. The income obtained from hatcheries has prompted several individuals to set up their own ventures as tourist attractions.

While there is an implicit advantage in the fact that the tourist season coincides with peak nesting, the disadvantage is that hatchery operators are more interested in making money by indulging the tourists than in conserving sea turtles. There are many potential dangers in using hatcheries for the conservation of sea turtles, and these are only exacerbated when the hatchery is established simply as a curiosity for visitors. In particular, factors that can affect proper embryonic development must be considered when a hatchery is established. If such factors as nest site, nest depth and dimension, moisture, temperature, etc. are not taken into account, "conservation" by means of hatcheries may be self-defeating and indeed may ultimately do more harm than good. The location of a hatchery should be one that imitates the natural nesting area as closely as possible. The methods should also imitate nature; for example, the potentially critical early hours of the turtle's life from nest emergence to entering the sea should be allowed to occur without interference.

A hatchery is a case of "all one's eggs in one basket". Localized erosion can sweep an entire hatchery into the sea. Flooding from heavy rains or the sea can cause 100% mortality to unhatched eggs. In addition, a hatchery can become a target for all the usual egg predators, including humans, unless it is well guarded. In Sri Lanka wooden poles tied close to each other surround the hatcheries. Some of these weak and/or poorly designed hatchery enclosures are broken or dug into by predators including pole cats, feral dogs, and cats. Some enclosures are located in the same place year after year because of insufficient space on the beach. Under these circumstances, egg residue from the previous season may promote bacterial growth and the release of toxic decomposition products into the new nests. To overcome this problem, the location of the hatchery should be changed seasonally. Some hatchery operators periodically change either the location of the hatchery or the sand, but this is not done regularly.

Protecting the eggs
Since wire mesh is expensive and wooden poles are scarce along the coast, most of the hatchery keepers resort to burying a large number of egg clutches in small enclosures. Nests placed close to each other may generate sufficient metabolic heat to raise the overall temperature a few degrees above that which is natural. Hatchling sex ratio is thermal-dependent, so the potentially higher temperatures in our hatcheries due to over-crowding may produce an unnaturally high proportion of females. The extreme of producing nearly all females is clearly detrimental to remaining stocks; a balanced sex ratio is essential. Valuable information on sex ratios of hatchlings in our turtle hatcheries is not available, as the sex of hatchlings cannot be determined visually.

Moving eggs can reduce hatching success rates from 90% in natural nests to 50-70% in hatcheries. But hatch success can be improved if the eggs are handled carefully. When selecting eggs for burial in Sri Lankan hatcheries, the development of the eggs should be considered. A white patch appears on the surface of all fertile turtle eggs after one day of incubation. Handling these eggs clearly results in higher mortality; thus, eggs with such white patches should be rejected by hatchery keepers. In Sri Lankan hatcheries there are no trained personnel to collect eggs. Eggs are brought to the hatcheries by villagers and sometimes they are a few days old. In spite of this, they are purchased by the hatchery operators. This is especially true during the off-season when there is competition amongst hatcheries for the available eggs. If discriminating operators were to reject eggs with white patches, these could be used for consumption. Only freshly laid eggs should be purchased by hatchery keepers in order to maximize the number of hatchlings ultimately released to the sea.

A weak start
In turtle hatcheries of Sri Lanka, hatchlings are retained in tanks for three days or more before being released to the sea. The reason for retaining hatchlings is attributed to a marine leech which attacks the abdominal slit of the hatchlings. However, there is a clear indication that hatchlings become weak if they are retained in tanks for too long. The weakened condition may make them more vulnerable to predators, thus reducing their chances of survival. Furthermore, we know so little about the imprinting mechanism of young sea turtles and their dispersal patterns. Holding them for a period of time during this critical stage may disrupt imprinting and dispersal, perhaps lessening the turtle's survival and/or its ability to return successfully to its natal beach to lay eggs of its own someday. The time, money, and effort spent on maintaining turtle hatcheries as a means of conserving turtles will serve no purpose if the hatchlings released from the hatcheries do not have a normal chance to survive into mature adults. In addition to the generally weakened condition of retained hatchlings, at some hatchery facilities hatchlings are crowded into small tanks where they have little or no space to swim about. In these crowded conditions hatchlings tend to nip at each other, causing injuries that are commonly invaded by secondary infections. Water in some of these tanks is not changed regularly, resulting in an unhygienic environment for the hatchlings. When all these adverse factors are accounted for, it is better to allow the hatchlings to reach the sea immediately after emergence, in order to increase their chances of survival. Finally, the practice of digging the transplanted nests to exhibit the eggs and allowing the tourists to release hatchlings even at mid-day has been observed in certain hatcheries. Activities such as these which will negatively and even fatally effect the normal development of hatchlings should be stopped.

Letting go
Some of hatchery operators are in the practice of releasing hatchlings out at sea. As was mentioned above with regard to retaining hatchlings in tanks, this "short circuit" may affect the vital imprinting mechanism which is thought to be necessary to enable the turtle to remigrate to the same location for nesting when it matures. Therefore, when releasing hatchlings they should be allowed to crawl across the beach naturally to the sea on the same evening as they emerge from their nests. Another unhealthy practice is the release of hatchlings at a particular time and location each day. Marine predators may become familiar with this routine and gather accordingly, resulting in excessive loss of hatchlings. To reduce predation, hatchlings should be released at selected points along the length of the natural beach. Hatchlings should never be released near artificial beach lighting or lighted offshore structures, as they may become disoriented.

Hatcheries can only be effective in protecting eggs from predators, including man, if corrective actions to overcome ongoing bad practices are undertaken. Enthusiastic individuals and organisations should be encouraged to set up turtle hatcheries using proper scientific techniques and designed to accommodate economic and labour constraints in Sri Lanka. There is a great need for national guidelines and regulations that govern the establishment and maintenance of turtle hatcheries in Sri Lanka. Careful monitoring and control of all the existing hatcheries by government officials or non-government organisations is essential to ensure proper hatchery maintenance. Each hatchery should be given a licence to operate and if mismanaged, this licence should be withdrawn. The priority in a sea turtle hatchery should be given to conservation -- and not to the attraction of tourists. It is very unfortunate that most of the existing hatcheries in Sri Lanka have their priorities reversed. It should be kept in mind that our local efforts are a vital part of the global effort by scientists, conservationists, managers, and policy-makers to assure the survival of sea turtles. We must do our part and we must do it professionally, both on behalf of local stocks and in support of the global effort to keep sea turtles from going extinct. (Courtesy Marine Turtle Newsletter)

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