Ranching and captive breeding

INTRODUCTION

‘Farming’ sea turtles has been proposed for over 30 years as potentially useful activity but remains divisive and controversial. Proponents promote farming as a method to save turtles, while opponents claim that farms actively contribute to sea turtle declines. This paper discusses the general implications of sea turtle farming from a conservation perspective to provide background for a discussion of what contribution farming and ranching might make to hawksbill sea turtle conservation in the wider Caribbean region. Discussion is restricted to sea turtles raised primarily for commercial purposes, the constraints imposed by sea turtle physiology, and whether such activities might have conservation benefits. The technical aspects of turtle farming are only presented in general terms. Wood and Wood (1980) and Jacobson (1996) provide an entry to this material.

There are two ways to "farm" sea turtles: (1) maintaining captive adults who breed in captivity and whose offspring are raised for use ("Captive Breeding", often termed "Farming") and (2) collecting turtles from wild populations ( as eggs or hatchlings) which are then raised in captivity for use ("Ranching"). These definitions are derived from the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which regulates international commercial trade from Captive Breeding and Ranching in different ways. In this paper, the term "farm" is used interchangeably to describe any facility holding captive turtles from either wild or captive bred sources, and sometimes both, for commercial production.

CONSTRAINTS ON FARMS

Three factors affect the practicality and economic viability of sea turtle ranching and captive breeding: their marine habitat, their slow growth rates (measured in decades in most wild populations), and our relative ignorance of their diseases and parasites. Sea turtles must be maintained in sea water and require locations near the sea and expensive systems to supply flowing salt water. Attempts to maintain sea turtles commercially in natural or artificial enclosures in the sea (e.g., fenced embayments and estuaries) have been uniformly unsuccessful. The high costs of enclosures, enclosure failure and animal escape, and difficulties with contaminated wastewater disposal have caused several facilities to abandon open enclosures in favor of closed ponds. Open enclosures also make presentation of food and temperature control inefficient. However, recent advances in open ocean enclosure husbandry of salmonid fish may provide a new perspective on this aspect.

Sea turtles have reptilian poikilothermic (cold-blooded) physiology and the species of most commercial interest (green turtles, Chelonia mydas and hawksbills, Eretmochelys imbricata) have a natural diet of very low nutrient and protein content. This causes natural growth rates and growth on natural diets to be so slow as to be uneconomical. For green turtles the natural diet comprises of sea grasses (marine angiosperms) and algae. Hawksbill turtles naturally eat sessile marine invertebrates, primarily sponges that contain dense fibrin and silica spicules and often have toxic or distasteful secondary compounds that may require physiologically expensive detoxification. Feeding natural diets is impractical. However, both species naturally eat a variety of marine invertebrates in the juvenile life stages (e.g. coelenterates, crustaceans) and can be induced to eat high protein foods when raised in captivity. Both species can be maintained on diets of fish and squid. Green turtles have been successfully raised on manufactured ‘turtle chow’ formulated with ideal rations of fiber, fat, protein and nutrients. There also seems no good reason why turtles could not be fed other animal byproducts appropriately processed, for example waste from fish or shrimp processing or chicken farms. Given sea turtles ability to process high fiber diets, the application of agricultural waste products such as corn stalks or sugar cane baggasse deserves investigation. However, at present such developments are completely speculative. The physical aspects of feeding such as supplies, storage, palatability, presentation, food wastage in water, fouling of enclosures, all require detailed attention.

Low quality food and low temperatures cause natural growth rates to be slow, increasing the expense of growing animals to economically marketable size. This can be offset by improving diet quality and protein content and providing warmer water, but these necessitate increased expenses. It has become routine in the husbandry of other cold- blooded animals to maintain temperatures at optimum levels for maximum growth (e.g., for crocodilians) but this requirement has not been well developed in turtle farms. Recent studies of natural growth rates suggest that increasing water temperatures by just a few degrees would result in significant increases in growth rate (Webb et al. pers. comm.). The aquatic habitat of sea turtles requires that this be provided in the form of heated water, which can be an expensive proposition unless solar heating or waste hot water (e.g., from power generators) can be provided but such advances have not yet been applied.

Sea turtles are also subject to a wide variety of pathogens and parasites. In natural situations and at wild population densities these may have imperceptible effects, but in crowded and often unhygienic conditions of captivity, epizootic diseases cause catastrophic mortality (e.g., Jacobson, 1996). Maintenance of water hygiene and competent veterinary care is crucial to successful husbandry. These in turn generate additional expenses for water handling equipment (pumps) and personnel. In areas of human occupation or countries with stringent environmental regulations, the disposal of wastewater contaminated with feces and nutrients can be an issue

These factors create constraints to sea turtle farms similar to other intensive aquaculture activities which require capital-intensive and technical responses. Experience suggests that low capital, low input, village level schemes are unlikely to succeed. Specialized technical expertise, veterinary supervision and intervention, water quality control systems, carefully balanced high protein diets, and water temperature control all enhance production and economic success but at high costs of production requiring that products be sold at high prices. Obtaining farm stock from wild sources is relatively easy, but this can create unrealistically low expectations about the amount of capital, time and skill that farm development will need. There is no currently operating economically successful sea turtle ranch and only one captive breeding farm (Cayman Island Turtle Farm, Grand Cayman Island).

For purely conservation purposes, funding to farm an organism is justifiable for species that are imminently in danger of extinction and for which in situ conservation mechanisms have been proven ineffective. Only one sea turtle, the Kemp's ridley (Lepidochelys kempii), approaches this situation. It is instructive that a captive ranching and release ("head-starting") program for this species instituted by the United States government was discontinued after 15 years and many millions of dollars , due to uncertainty about the results and other concerns (Byles, 1993; Williams, 1993; Eckert et al., 1994). Long term head-starting programs, including those focusing on green turtles (Florida, USA; Huff, 1989) and hawksbills (Republic of Palau; Sato and Madriasau, 1991.) have also been discontinued in recent years based on insufficient evidence of success.

SPECIAL FEATURES OF HAWKSBILL SEA TURTLES

As indicated above, hawksbill sea turtles have an unusual diet of marine invertebrates. It is not yet clear what effects this has on their digestive physiology and how this might affect captive husbandry. Researchers, aquaria and some turtle farms have attempted to raise small numbers of hawksbills. Their general experience is that this species is difficult to raise in captivity. Hatchlings are relatively aggressive and if kept together, bite each other causing injuries that can be become infected and cause death. Ridley turtles (L. kempi) have similar behavior and the US government program to raise this species resorted to holding each hatchling in an individual container. One advantage of hawksbill turtles may be that their products (primarily bekko or tortoiseshell) have a very high value. If this species can be raised to a size that will produce marketable bekko (a proposition that remains undemonstrated) then the high yield may justify high expenditures on facilities and care that make the effort economically feasible. It does seem likely that in common with similar programs for captive rearing crocodilians (another high unit value species) economic success will require optimizing both growth rate and survival in captivity in order to ensure that revenues exceed the high fixed costs. There is a substantial regulatory burden of international (CITES) and national regulation. It must also be acknowledged that political and emotional opposition to trade in this species is a significant impediment to developing commercial use and trade.

HISTORY OF FARMING

Three attempts have been made to develop facilities for raising sea turtles commercially; by captive breeding and ranching, at Grand Cayman Island (U.K.) in the Caribbean, and ranching wild collected hatchlings in Reunion Island (France) in the Indian Ocean, and in the Torres Straits islands (Australia), all with green turtles. Facilities were also started or planned in Suriname (Reichart, 1982) and Indonesia and are currently under development in Cuba.

Cayman Turtle Farm: Cayman Turtle Farm (CTF) was started under the name Mariculture Ltd. in 1968 using green turtle eggs obtained from Suriname, Ascension Island, and Costa Rica. The farm initially attempted to raise turtles in semi-natural surroundings, but quickly converted to closed tank systems located on Grand Cayman Island. Adult breeding stock was obtained from Mexico, Suriname, Costa Rica, Guyana, Nicaragua, and Ascension Island and these began laying eggs in captivity in 1973. Most of the farm's production was from wild eggs collected under license from Ascension Island, Suriname, and Costa Rica (constituting "ranching" in the present sense). The farm conducted intensive studies of reproductive biology of sea turtles and successfully bred captive raised sea turtles in 1975, and by 1978 discontinued importation of wild eggs, relying entirely on production from both wild caught and captive-raised stock. Deep controversy ensued over whether CTF had legitimately achieved captive breeding that met CITES definitions of the time, and concerns about the effects of re-opening the quiescent international trade in sea turtle products.

As a result of international opposition from the scientific community, CTF did not receive CITES approval to trade internationally. In 1979, CITES adopted a captive breeding definition requiring production of second generation offspring which CTF had difficulty meeting. Lacking CITES approval, the farm could not sell its products anywhere except the U.K. (being a U.K. dependency, such trade was considered domestic). The U.S. Endangered Species Act of 1973 prevented import or transshipment through the U.S., greatly restricting CTF's marketing and sales. The farm went through a number of changes in ownership and serious economic difficulties. The addition of a component of tourism and diversification of products including shell, oil and local sales of turtle meat in Grand Cayman failed to provide sufficient revenue. CTF entered bankruptcy in 1975 and was taken over from the second owners by the Cayman Islands government in 1983. Since then, CTF has continued to operate at a reduced scale largely as a tourist facility and to provide employment and turtle meat for the local market. The farm also releases immature green turtles into the waters around Grand Cayman Island (Wood and Wood, 1993). The farm returned its first operating profit in 1988, 19 years after establishment. The farm has successfully raised and bred a small number of hawksbill turtles.

Farm Corail, Reunion Island: Sea turtle farming began on an experimental basis in 1972 under the direction of the Institutes de Peches on Reunion Island, a French overseas Department located in the southwestern Indian Ocean (Lebrun, 1975). The farm was stocked with hatchlings collected annually from green turtle nesting beaches on Tromelin and Europa islands located 600 km and 2,000 km distant, thus operating as a ‘ranch’. The farm has been producing meat and shell for sale to tourists and the French domestic market since about 1980. Several attempts to apply for international trading privileges under CITES were unsuccessful and the farm remained oriented toward its local and domestic market and with a reduced scope of operations. The facility has had consistent problems with slow growth and disease which are attributed to the artificial pelletized diet and the seasonally low water temperatures in the area. In 1996-1997, Farm CORAIL (Compagnie Reunionnaise d’Aquaculture et d’Industries Littorales) negotiated a transition to fish aquaculture, research and education. No new turtle stock has been introduced and the release of captives is proposed. Turtle tracks at the two nesting islands of Tromelin and Europa have been regularly counted to support the premise that the annual hatchling collection does not threaten the nesting colony. The data indicate normal fluctuations, but no decline in either population over the period of hatchling exploitation (Le Gall et al., 1986). The farm successfully maintains some wild caught adult hawksbills.

Torres Strait: Following initial studies by the National University of Australia, an organization created by the Australian government to assist development in aboriginal communities established a network of village-level sea turtle ranches on the islands of Torres Strait, Australia, in 1970. Green turtle eggs collected from the large nesting aggregations at Bramble Cay and Rayne Island were transported to about 150 villagers located on islands in the Torres Strait. Difficulties with low hatch rates and high mortality were experienced at an early stage. The project was critically evaluated in 1972 (Carr and Main, 1973) and reorganized to concentrate turtle raising on nine islands with more intensive technical support, each with a capacity for 100-500 small turtles. During the period 1974-1978, the project undertook research on husbandry and disease, as well as general studies of sea turtle biology in the region, but was unable to overcome the basic problems of limited food supplies for young turtles and disease and parasites. In 1980, after government expenditure of six million Australian dollars , the project was terminated. Several attempts to raise clutches of hawksbills in this program failed.

BENEFITS AND DISADVANTAGES

A variety of conservation advantages and detriments have been claimed for turtle farms. These all lack objective or quantifiable information to evaluate them, which has led to a highly polarized and emotional discussion of these factors with little resolution. Ehrenfeld (1974) and Hendrickson (1974) provide two contrasting views.

Production of a food source for tropical coastal people: The prospect of using sea turtles to produce high quality protein from unproductive tropical marine systems and provide food for residents of tropical countries was initially supported by Carr (1967) and later strongly self-criticized (Carr, 1984). The high cost of growing turtles to edible size ensures that the price of farmed turtle meat is higher than wild caught turtle. To recover costs, turtle farm products must be sold to overseas markets or tourists (Ehrenfeld, 1982; Dodd, 1982). The flavor of captive turtles fed non-natural diets is alleged to be inferior to that of the wild product, causing low acceptability among coastal people used to the real thing. Farmed turtle has therefore not proven to be the low cost protein source originally envisaged.

Substitute for wild products: Production of turtle products in large quantities from farmed animals has been claimed to reduce demand for products from wild caught turtles in both local and international markets, extending protection to wild turtle populations. In the special case of hawksbill turtles, provision of turtle shell (bekko) from a farms to satisfy a single well regulated market in Japan has been proposed as a solution to widespread illegal wild harvest. The high price of farmed products may exclude them from most local markets. Critics of farms, and of commercial use and international trade in turtles in general, argue that any increase in the availability of products on the international market will stimulate demand, which existing farms will be unable to satisfy, increasing pressure on wild populations and trade through illegal channels. Objective evidence on the reality of this scenario is contradictory, and some economic theory would argue that such stimulation is illusory. Clearly, effective national regulations and strict control of trade to prevent illegal commerce is necessary to prevent or minimize any such effect. Examination of other wildlife trade such as parrots, ivory and crocodile skins suggests that legal trade can largely replace illegal trade, although some illegal take from the wild continues. The argument that legal trade will increase demand above the level that farms can supply deserves objective testing.

Removal of animals from wild populations to stock farms: In both captive breeding and ranching, stock must be removed from the wild. For captive breeding, a relatively small number of adult breeders of both sexes are required. The very high reproductive value of such adults to the population, as determined by modeling studies (e.g., Crouse et al., 1987), may make the ecological effects of such removal significant, although data are lacking. For ranches, a continuing supply of eggs from breeding beaches is required. Some schemes for egg removal have used spurious models of sea turtle biology to support unreasonably high levels of collection (see Heppell et al., 1995). Continued removal of a majority of the eggs must eventually cause population collapse. However, considering the life history strategy of sea turtles and the very high natural mortality of younger stages, it can be convincingly argued that removal of a small proportion of eggs is likely to have little effect on adult recruitment. If such egg collection was linked to effective protection of nesting females and eggs remaining at the nesting beach, then non-detriment is highly probable. More knowledge about juvenile survivorship and density dependent constraints on adult recruitment are needed to evaluate this factor and estimate what proportion of eggs may be safely harvested.

Animals for release/restocking: A proportion of the turtles raised on farms can be released back to the wild. Because of the presumed high mortality of sea turtles in the smaller size classes, largely from predation, it is argued that recruitment to wild breeding populations can be augmented by releasing larger sized turtles that are less subject to predation in a process termed "head-starting." Proponents point to documented cases of long term survival of released turtles, and growth and movements suggesting that they have successfully adapted to the wild (Wood and Wood, 1993). Although a few head-started Kemp’s ridley turtles have joined a breeding population at Padre Island, Texas (Shaver, 1996; Shaver and Caillouet, 1998), critics argue that head-starting compromises the complex migratory movements of sea turtles in their subadult years, and abnormal behavior has been observed in head-started animals. (Dodd, 1982). The aberrant behavior and movements of some newly released turtles are widely documented. The potential introduction of disease and parasites from released captives into wild populations is also a serious concern (Jacobson, 1996), and there are further concerns about releasing turtles from different genetic stocks into wild populations (Dodd, 1982). Criteria for evaluating the success of head-starting are described in Eckert et al. (1994). Current theory and practice regarding re-introduction of captive stock to restore wild populations (IUCN re-introduction guidelines 1995) require extensive pre and post release monitoring for genetic integrity, health, habitat suitability and post-release survival and breeding.

Research: Farms provide a unique opportunity to study some aspects of the biology of sea turtles. Holding turtles in captivity allows manipulation and experimentation that is not possible in the wild. CTF made major contributions to the understanding of the physiology of sea turtles, supporting research by visiting scientists and making its facilities and animals available for studies (Owens, 1995). The farm undertook to hold and breed the highly endangered Kemp's ridley turtle starting in 1980, and by 1984 was successfully breeding and raising this species. The farm successfully solved numerous husbandry problems involving nutrition, disease and reproductive physiology. Farm research is often directed toward questions of maintenance and husbandry that have only indirect application to conservation and wild populations. However, most commentators concede that the research activities, particularly those at CTF, have been broadly beneficial to our general understanding of sea turtle biology.

RANCHING VERSUS FARMING

Ranching and closed cycle captive breeding (‘farming’ sensu CITES) differ in some significant aspects of their costs and conservation value. Captive breeding requires the maintenance of captive adult stock, entailing expense, and the manipulation of natural breeding behavior. At the Cayman Turtle Farm this was achieved by a technically complex and invasive hormone manipulation. The large clutch size and multiparity of sea turtles makes captive breeding relatively productive and captive egg production is predictable and under the farmers’ direct control. Some captive green turtles have been induced to lay on an annual cycle. The disadvantages to the farmer are high costs, risk of reproductive failure and additional technical requirements. The disadvantage to conservation is that after acquiring breeding stock, a successful closed cycle captive breeding operation has little dependence on or interest in the wild population. There are no direct economic incentives for conservation of the wild population or its habitat. Recently concern about ex-situ captive breeding outside range states has been raised as a theft of biodiversity value and an infringement of sovereign rights.

In contrast, the ranch operation, obtaining stock every year from the wild in the form of eggs or hatchlings has an absolute and direct interest in maintaining wild populations. The costs of population monitoring can be made a direct cost of operation and a condition of access to the wild resource. The disadvantage is that the supply of stock may be variable in both quantity and quality and subject to the caprice of both nature and regulatory bureaucracy. Ranch operators often seek to convert production to more controllable captive production and many successful commercial wildlife operations combine both. Ranching and farming are therefore not mutually exclusive and may be combined in effective ways to optimize both conservation, regulatory and economic benefits.

In both farming and ranching an effective regulatory framework is necessary to ensure that the facility does not serve as a conduit for illegally taken wild products. An effective government infrastructure and cooperation of the commercial sector greatly facilitates this. There is also a need for any commercial use of wildlife resources, including sea turtles, to return a proportion of revenue to pay for the costs of managing and conserving the wild population. In the case of ranches this is easily achieved by access fees and payments per unit (e.g. egg) collected from the wild. In this way the true cost, including hidden conservation costs, can be transparently accounted. For captive breeding this must be achieved indirectly e.g., by license fees and severance fees on products.

CITES GUIDELINES

A new perspective was introduced between 1992 and 1994 when a task force of the Animals Committee of CITES was assembled to draft guidelines for the evaluation of proposals to CITES for ranching sea turtles under Resolution 3.15 Ranching of the Convention. Attempting to move beyond the unproductive arguments of the past, the task force proceeded under two broad assumptions: (1) the conservation benefits required by Res. Conf. 3.15 (and also needed to satisfy a very skeptical conservation community) must be made explicit in any ranching proposal, and (2) the solution to all the issues raised about effects of increasing international commerce in turtle products must be met by a very strict control of international trade.

Returning to the fundamentals of sea turtle biology, the task force recognized that because of their migratory habit, sea turtles were rarely or never solely the jurisdiction or "property" of a single nation and therefore represented a special case for CITES which justified some extraordinary solutions. Responding to the most recent results on the genetic composition of sea turtle populations, and on a long recognized need for international cooperation in sea turtle conservation, the task force proposed that genetic population units be defined and all the nations in which members of a population spent time be identified. Communication, cooperation and a regional approach to conservation of the population were then proposed as a necessary component of any ranching proposal for that population.

To address the need for effective trade controls, the task force proposed measures that would prevent sea turtle products from entering trade from any source except legal, approved ranches, and again called for international and bilateral cooperation between producing nations and consuming nations to achieve this. The application of restrictive closed trading agreements limited to single producers and single markets was proposed. This runs contrary to current free trade thinking, but based on similar models for other very valuable wildlife products like ivory, it may be feasible. The marking of products to unambiguously differentiate legal farmed products from any other was also mandated. Proposals presented at the Conferences of the Parties to CITES by Cuba and Japan suggested feasible mechanisms to meet the demand for stringent trade control.

These two new approaches to ranching allowed a prospective scenario where a sea turtle ranching project would become the vehicle for regionally coordinated conservation programs. The application of similar guidelines for all commercial sea turtle use is similarly feasible. Lack of funds to develop research, conservation and enforcement is the major impediment to all sea turtle conservation. By linking the development of commercial sea turtle ranches and farms to required conservation activities, a source of funding, an incentive, and political support to meet the CITES guidelines could be encouraged.

In 1994 the CITES Parties and others reached consensus on sea turtle ranching guidelines at COP 9 and adopted adopted CITES Res. Conf. 9.20 Guidelines for Evaluating Marine Turtle Ranching Proposals Submitted Pursuant to Resolution Conf. 3.15 Ranching ). The requirements for regional cooperation and scientific and biological knowledge are difficult obstacles to meeting these new guidelines. The guidelines have not been utilised. It remains to be seen whether the new guidelines are feasible and can indeed be applied as they were conceived to be a very positive factor for sea turtle conservation.

CONCLUSION

Sea turtle farms, whether for captive breeding or ranching, cannot be shown to be directly beneficial or proven to be fatally detrimental to the conservation of wild populations. What can be demonstrated is that they are very expensive, require advanced technical knowledge, and are, to date, of unproved economic viability. The linkage of farms to direct conservation activities and strict trade control, through international cooperation, provides the potential that farms could contribute to the conservation of sea turtles, but this potential remains unrealized.

References

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Carr, A. 1967. Caribbean green turtle, imperiled gift of the sea. National Geographic Magazine 131:876-890.

Carr, A. 1984. The Sea Turtle: So Excellent a Fishe. Univ. Texas Press, Austin. 280 pp.

Carr, A. F. and A. R. Main. 1973. Turtle farming project in Northern Australia. Union Offset Co. Pty., Ltd., Canberra, Australia. 42 pp.

Crouse, D. T., L. B. Crowder and H. Caswell. 1987. A stage-based population model for loggerhead sea turtles and implications for conservation. Ecology 68:1412-1423.

Dodd, K. 1982. Does sea turtle aquaculture benefit conservation? p.473-480. In: K. A. Bjorndal (Editor), Biology and Conservation of Sea Turtles. Smithsonian Inst. Press, Washington D.C.

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Ehrenfeld, D. 1982. Options and limitations in the conservation of sea turtles, p.457-463. In: K. A. Bjorndal (Editor), Biology and Conservation of Sea Turtles. Smithsonian Inst. Press, Washington D.C.

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Huff, J. A. 1989. Florida (USA) terminates "headstart" program." Marine Turtle Newsletter 46:1-2

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Lebrun, G. 1975. Elevage a la Reunion de juveniles de la Tortue Verte Chelonia mydas (Linnaeus 1758). Science et peche. Bull. Inst. Peches marit. No. 248:1-25.

Le Gall, J., P. Bosc, D. Chateau and M. Taquet. 1986. Estimation du nombre de tortues vertes femelles adultes Chelonia mydas par saison de ponte a Tromelin et Europa (Ocean Indien) (1973-1985). Oceanogr. trop. 21:3-22.

Owens, D. W. 1995. Book Review: Last Chance Lost? Or is it? Marine Turtle Newsl. 71: 11-12.

Reichart, H. 1982. Farming and ranching as a strategy for sea turtle conservation, p.465-471. In: K. A. Bjorndal (Editor), Biology and Conservation of Sea Turtles. Smithsonian Inst. Press, Washington D.C.

Shaver, D. 1996. Head-started Kemp's ridley turtles nest in Texas. Marine Turtle Newsletter 74:5-7.

Shaver, D. and C. W. Caillouet, Jr. 1998. More Kemp's ridley turtles return to South Texas to nest. Marine Turtle Newsletter 82:1-5.

Sato, F. and B. B. Madriasau. 1991. Preliminary report on natural reproduction of hawksbill sea turtles in Palau. Marine Turtle Newsletter 55:12-14.

Williams, P. 1993. NMFS to concentrate on measuring survivorship, fecundity of head-started Kemp's ridleys in the wild. Marine Turtle Newsletter 63:3-4.

Wood, F. and J. Wood. 1993. Release and recapture of captive reared green sea turtles, Chelonia mydas, in the waters surrounding the Cayman Islands. Herpetological Journal 3:84-89.

Wood, J. and F. Wood. 1980. Reproductive biology of captive green sea turtles, Chelonia mydas. Amer. Zool. 20:499-505.

James Perran Ross
Florida Museum of Natural History
Department of Natural History
University of Florida
Gainesville, Florida 32601 USA
Tel: (352) 392-1721; Fax: 392-9367
email: prosscsg@flmnh.ufl.edu

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