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WT/DS58/R
(15 May 1998
(98-1710)

United States - Import Prohibition of Certain Shrimp and Shrimp Products

Report of the Panel

(Continued)


Dr. J. Frazier:

5.38. It is certainly true that "biologists consider that sea turtle populations around the world are affected by various factors". The life cycles of all species of sea turtles are very complex: the animals depend on terrestrial areas of sandy beaches to make their nests and deposit their eggs (Miller, 1997; Ackerman, 1997); hatchlings (newly-hatched turtles) of all species, except the Australian flatback, disperse into open ocean, and live as part of the epipelagic (open ocean) assemblage on the high seas (Musick and Limpus, 1997); immatures of many species take up residence in coastal areas, and may pass through a series of "developmental habitats" before reaching maturity; adults migrate between feeding areas and nesting areas (Musick and Limpus, 1997). Depending on the species and "population", these migrations may occur every one, two, three or more years, and can involve displacements of thousands of kilometers, in some cases crossing ocean basins (Meylan, 1982a; Bowen and Karl, 1997). In the wild, sea turtles require more than a decade (several decades in some species) to reach maturity (see references in Bjorndal and Zug, 1995; Chaloupka and Musick, 1997), and they have the capability to live for many decades, during which time they continue to reproduce.

5.39. Hence, during its long life, an individual sea turtle will pass through many different environments, traversing a substantial - often vast - surface of the planet; in any one of these environments, and at any time during its long life, it may meet a large variety of predators and other threats. For turtle eggs laid on beaches, these threats include ants, flies, beetles, crabs, snakes, and lizards, as well as birds and mammals of many varieties; the hatchling turtles are liable to many of the same terrestrial predators, as well as a diversity of marine fishes. Even immature and adult sea turtles are not free from predation, and can be attacked by large fishes and carnivorous mammals, both in the sea and on land (Stancyk, 1982). The list of human-caused (anthropogenic) threats to sea turtles is also long and includes fishing activities, coastal development, marine and coastal pollution, and even upland pollution and deforestation (Eckert, 1995; Lutcavage et. al., 1997).

5.40. For this reason, depending on the time, place and circumstances, the factors affecting a particular sea turtle, or stock of sea turtles, will vary. Anthropogenic factors add to an already enormous list of threats that sea turtles face during the course of their normal life cycle. People can prey on and impact those stages of the life cycle when turtles would otherwise be least vulnerable to predation. Anthropogenic risks can also include large scale perturbations of habitat, thereby increasing mortality, both in time and in space, e.g., the chronic effects of marine pollution or the total devastation of a nesting beach.

5.41. Because sea turtles live for long periods of time and they require decades to reach maturity, it may take years to perceive the effects of loss from the "population". Hence "current" threats may in effect be the results of past actions and damage, which only now are being detected. It is also worth clarifying that the concept of "population" is not easily defined for sea turtles, due to their complex migratory patterns and life cycles; recent information on genetic composition is resolving this problem (Bowen, 1995; Bowen and Karl, 1997; Chaloupka and Musick, 1997: 235). However, in the absence of such information, many specialists prefer to employ the terms "reproductive unit", "breeding stock" (Chaloupka and Musick, 1997) or "management unit" (Bowen and Karl, 1997). In the present review, the term "population" is used simply because it is in common use.

5.42. The terms "threatened" and "endangered" have specific significance to organizations such as the IUCN (World Conservation Union) and CITES. A recent evaluation of these categories, by specialists of the IUCN (Bailley and Groombridge, 1996), concluded that the appropriate categories for sea turtles are as follows:

Caretta caretta endangered
Chelonia mydas endangered
Dermochelys coriacea endangered
Eretmochelys imbricata critically endangered
Lepidochelys kempii critically endangered
Lepidochelys olivacea endangered
Natator depressus threatened

5.43. At a general level, the decline of any animal population can be attributed to the same causes: that recruitment of new animals into the population cannot keep up with loss of animals from the population. On a more detailed level, the causes of decreased recruitment and/or increased mortality (or emigration) vary according to time, place and a variety of conditions. Unfortunately, there are several basic factors in sea turtle biology which are not well known, these include: age at maturity, reproductive lifetime, reproductive output, rate of mortality in different life stages, and sex ratio in the wild. Hence, in many cases our lack of fundamental information makes it difficult to dogmatically assign simple "causes" to any decline (or recovery) of a population.

5.44. What is known and widely accepted, is that - with few exceptions - the numbers of marine turtles that are found nesting around the world are far less today than they were historically or within living memory (e.g., Frazier, 1980; King, 1982; Ross, 1982; National Research Council, 1990; Chan, 1991; Limpus, 1994; 1995; Limpus and Reimer, 1994; Witzell, 1994; Chan and Liew, 1996b; Liew, in press). In many instances, although systematic or quantitative data are not available, general historic accounts or comments of long-time residents of coastal areas reveal clear declines in numbers of turtles (e.g., Clifton et. al., 1982; Cornelius, 1982; Frazier, 1982; Kar and Bhaskar, 1982; King, 1982; Polunin and Nuitja, 1982; Ross, 1982; Spring, 1982; Jackson, 1997). Indeed, systematic, quantitative information on status is available for very few sea turtle populations.

5.45. With few exceptions, the status of sea turtle populations is evaluated on the basis of the numbers of females, or more commonly, the numbers of nests (or even numbers of eggs) recorded on a nesting beach during a nesting season. The reason for this is simply because it is far easier, and much less expensive, to observe and count what happens on a beach than what happens in the sea.

5.46. Attempts to estimate the number of turtles in a population (immatures, adult males and adult females) are foiled by a lack of basic information on demography of sea turtles (Crouse et. al., 1987; Van Buskirk and Crowder, 1994; Crouse and Frazer, 1995). In fact, even estimating the numbers of reproductive females in a population presents a major challenge. With the exception of ridley turtles, female sea turtles typically nest several times during a season, and then not again for two or three years, or more. Individual females may nest at two-year intervals and then change to three-year intervals, or vice versa (Carr et. al., 1978) so even though they return periodically to lay their eggs on the same beach, there is not even a simple - reliable - way to estimate the number of adult females in a sea turtle population (Crouse and Frazer, 1995).

5.47. In the case of ridley sea turtles, which in addition to nesting annually, nest in great concentrations, arribadas, the challenge of estimating the numbers of nesting females is complicated for additional reasons. During arribadas, the density and commotion of females on the beach makes it physically impossible to accurately count every female that nests. At different arribada beaches different methods have been used to estimate the numbers of females, but these methods tend to be rather rough, without clear consistency between years, and rarely statistically sound (viz. they rarely are based on defensible statistical procedures, and do not include confidence limits, making statistical comparisons between numbers impossible). Two different methods, designed to derive confidence limits, are used at Nancite, Costa Rica, and they produce results which can be very different (Clausella, pers. com.). The most thorough attempt to develop a statistically defensible counting procedure for concentrated nesters has recently been presented by Gates et. al. (1996), but it is not yet in common use.

5.48. Whatever the species, numbers from nesting beaches must be interpreted with great care. In the first place, the methods and effort involved in counting must be comparable. It is not uncommon for effort and efficiency in patrolling a beach, or collecting eggs, to increase as personnel in a programme acquire more experience, and perhaps more support. For example, over the past five years increasing numbers of hawksbill nests have been recorded on the Yucatan Peninsula, in southern Mexico. In part, this is because more turtle camps have been established, some of the camps are better equipped, and there is more attention and concern on part of the local populace to protect sea turtles. However, there are also indications that at some individual beaches, the numbers of nests per season has increased.

5.49. Even when methodology and effort are comparable from year to year, data from nesting beaches must be interpreted with caution. Nesting populations, thought to be free from large scale predation, can show tremendous changes in numbers from one year to the next. For example, on Heron Island, Great Barrier Reef, about 1,100 green turtles nested in 1974-75, and the following year only about 50 nested. During peak nesting season on remote Raine Island, also in Australia, it was estimated that 11,000 females came ashore in one night during the 1974-75 season, but there were only about 100 on the beach in any one night the following year (Limpus, 1982). Similar large variations have been recorded on other green turtle nesting beaches (Meylan, 1982b; Hirth, 1997: 73). In the case of Australian beaches, these fluctuations in numbers of nesting green turtles can be predicted by an index of the Southern Oscillation ("El Niño"), but in other cases it is unknown what causes the fluctuations (Limpus and Nicholls, 1988).

5.50. Yearly variations in nesting are reported to be greatest with green turtles, but annual fluctuations in nesting activity (numbers of nesting females, numbers of nests and/or numbers of eggs) occur in all species of sea turtles; some loggerhead beaches have had tremendous variation from year to year, for which there are no simple nor clear explanations (Meylan, 1982b; National Research Council, 1990; Chaloupka and Musick, 1997). Thus, to fully understand the dynamics of a population requires long-term data, for apparent trends over a few years may not reflect true changes in the total numbers of animals in the population but rather the physiological condition of those animals that migrate to breed, the condition of their feeding areas, etc. (Limpus and Nicholls, 1988; National Research Council, 1990; Crouse and Frazer, 1995; Chaloupka and Musick, 1997).

5.51. A further complication is that individual females generally nest more than once in a single nesting season. But, the number of nests per female varies, even for the turtles sharing the same beach, during the same nesting season. Hence, there is no precise conversion from number of nests to number of nesting females. Using numbers of eggs to derive numbers of females in a season is even more tenuous, because of the added variation in clutch size, both between females and between subsequent clutches of the same female.

5.52. This having been said, there are some cases in which it is possible to relate certain documented changes in a population indicator to a major perturbation in the environment which clearly has had a significant impact on a sea turtle population. For example, direct, unrelenting exploitation of reproductive green turtles in the Seychelles, directed for an export market, was quickly followed by dramatic declines in "annual production" (i.e., numbers of animals captured per year), and in the general abundance of the animals (Frazier, 1980). Similar examples of direct exploitation of both breeding and non-breeding green turtles accompanied by decimation of their numbers are known for the Caribbean (Jackson, 1997), the southern United States (Witzell, 1994), Pacific Mexico (Clifton et. al., 1982), and many other parts of the world (King, 1982; Ross, 1982). Breeding olive ridleys in Pacific Mexico were also heavily exploited, with consequent decimation in their numbers (Clifton et. al., 1982). Throughout the Caribbean, hawksbills have declined drastically, in conjunction with heavy exploitation in both nesting and non-nesting animals (Meylan et. al., in prep.).

5.53. Where no direct exploitation on breeding turtles is recorded, declines in populations have been attributed to intense direct exploitation of eggs, for example in Sarawak, East Malaysia (Limpus, 1994; 1995; Chan and Liew, 1996a). But at least in the case of the Terengganu leatherbacks in Western Malaysia, the decline is thought to have also been influenced by incidental capture and mortality, first in a local fishery, and then in a high seas fishery (Chan and Liew, 1996a).

5.54. In addition to direct exploitation, indirect factors are also known to cause major impacts on sea turtles. For example, declines in loggerheads in Georgia and South Carolina are clearly linked to incidental mortality in shrimp trawls (National Research Council, 1990). Dramatic declines in Pacific leatherbacks have been related to an increase in fisheries activities in South America, and incidental mortality in fisheries using drift- and gillnets (Eckert and Sarti, 1997).

5.55. It is important to realize that multiple, sequential causes can be attributed to the decline of a population, as was explained by Chan and Liew (1996a) in the case of the Terengganu leatherbacks. This case illustrates the danger of attributing simple causes to what appear to be simple phenomena relating to sea turtles. Because of their complex life history, the researcher must be ever vigilant of effects which may take place in some area or time, out of view, and distant to one's area or period of operation; important sources of mortality may take place on the other side of an ocean basin, or a decade before a study is carried out. This is even further complicated because the same beach may be used by turtles that feed in very different places, or turtles that feed in the same areas may nest in very different places (Carr et. al., 1978). Hence, a significant source of mortality may occur at some point during the long generation time of a cohort of sea turtles, but if that factor is not observed during a study, it will be easy to ignore it and attribute the decline to other causes. The challenge in explaining the demography of sea turtles is one of identifying major factors over large periods of time, and over large expanses of the sea.

5.56. In regards to the five countries specifically involved in this report, reasons attributed to declines can be summarized as follows:

India: Green turtles in the Gulf of Mannar appear to have declined, following heavy exploitation of animals at sea for local consumption and occasionally for export (Frazier, 1980). In general, however, systematic data are wanting for the majority of sea turtle populations in India, and it is only possible to compare what little is known of the present-day situation with general accounts of naturalists or long-term coastal residents. For example, intensive development and human immigration on the coast of Tamil Nadu has resulted in extensive habitat perturbation as well as intense exploitation of olive ridley turtle nests. Thus, it is thought that the numbers of olive ridleys here are much lower than years ago. There is a similar supposition that green turtles in Gujarat have declined, but clear trends are not possible to determine in the absence of systematic information. There are conflicting opinions about the current trends of the massed nesting beach for olive ridleys at Gahirmatha (Mohanty-Hemadi and Sahoo, 1994; Pandav et. al., 1997).

Malaysia: Declines in egg production has been attributed to heavy harvest of eggs of green turtles at Sarawak (de Silva, 1982; Limpus, 1994; 1995), and in Sabah heavy pressure from hunting at sea and on nesting beaches as well as intensive egg harvests occurred prior to declines in egg production (de Silva, 1982; Eckert, 1993; Limpus, 1994; 1995; Chan and Liew, 1996b). In both Sabah and Sarawak, habitat degradation (marine and terrestrial), and fishing activities - notably trawls - have been identified (Leh, 1989; Suliansa et al., 1996). Egg production of green turtles in Terengganu (as well as Kelantan and Pahang) declined following heavy egg harvest, coastal development and intensification of coastal fisheries activities (Siow and Moll, 1982). Numbers of eggs of leatherback turtles at Terengganu show a well documented precipitous decline (Siow and Moll, 1982; Chan, 1991; Limpus, 1994, 1995) which has been related to nearly complete egg harvest for decades, as well as incidental mortality first in coastal fisheries, and then in high-seas fisheries (Chan and Liew, 1996a). Nesting by green and hawksbill turtles on the west coast of Malaysia has declined following intensive coastal development and fisheries activities, especially prawn trawling (Siow and Moll, 1982). Limpus (1995) states that from possible thousands of olive ridleys nesting annually in Terengganu, there may now be 20 per year nesting. Chan (1991) explained that in Malaysia, all five species of sea turtles are considered to be critically endangered.

Pakistan: Data on the numbers of nests at Hawksbay, Sind, indicate declines in both green turtles and olive ridleys from 1979 to 1995 (Firdous, in press). However, there has been no detailed analysis of these data. Very little is known from Baluchistan, but sizable populations of green turtles are thought to occur (or to once have occurred) there. Groombridge et al., (1988) reported commercial exploitation (thought to be green turtles) from remote beaches in Baluchistan. The levels of harvesting were claimed to have been many thousands of turtles in a year; a short-term exportation to Japan was involved, but there was also evidence that much of the exploitation was for local consumption. Later, Groombridge (1989), in reporting on Baluchistan, stated "Incidental catch appears to be a problem in surrounding waters...". He suggested that the nesting colony in the Sonmiani region of Las Bela may have been extirpated by heavy direct exploitation. As the area is remote, and much of the exploitation is for locally consumed products not recorded in normal statistics, it is next to impossible to know what happened historically or even what has happened in recent years.

Thailand: Polunin and Nuitja (1982) explained that little systematic information has been available, but data on egg yields from Phangnga and Ko Khram (probably mainly green turtles) indicated clear declines. Intensive coastal development and reef blasting were reported to have eliminated much nesting habitat. All evidence pointed to serious depletion in the Gulf of Thailand (Polunin and Nuitja, 1982). Phasuk (1982) identified uncontrolled harvest of eggs and turtles, as well as incidental drowning in trawls; to these causes were added habitat modification (Lekagul and Damman, 1977; Ginsberg, 1981). Direct and heavy ("near total, long term") harvest of eggs has been described as the principal cause of declines of green turtles and leatherbacks (Limpus, 1995). Limpus (1995) stated that overharvest of eggs has been responsible for the dramatic declines of olive ridleys that once nested on the Andaman Sea coast of Thailand, which have been decimated to only tens of females per year. This focus on egg harvest is because there is some systematic information available on this activity, unlike incidental kill and harvest of turtles (Eckert, 1993). The most recent review of the situation at Khram Island and other main nesting areas, including the Andaman sea coast, has concluded that there have been significant declines in green and hawksbill turtles. In Khram this was reported to have been caused by heavy fishing activities, while at other areas coastal development, egg poaching and incidental capture in gill nets, long lines, and trawls have been implicated (Supot, in press).

United States: Historic declines of green turtles, due to intensive exploitation at sea for commercial purposes, has been documented for coastal waters from Texas to Florida (Witzell, 1994). Loggerhead nesting has declined in Georgia and South Carolina, due especially to incidental capture in shrimp trawls (National Research Council, 1990). Population declines of loggerheads in these two states are thought to continue, but to a lesser extent, because of reduced mortality from the use of TEDs (Crowder et al., 1995). There have been dramatic declines of sea turtles - notably green turtles - in Hawaii (Balazs, 1980). Declines of both green and hawksbill turtles have been documented for most other US island territories in the Pacific, related to hunting (legal and illegal) eggs and meat, habitat degradation and incidental catch (Eckert, 1993).

5.57. In general terms, the causes have been similar in different parts of the world: an inability of recruitment to match mortality. (Little is known of the processes of immigration and emigration in sea turtle populations, so for simplicity, these terms will not be used here.) However, specific conditions vary, depending on different circumstances (see comments above), so recruitment and mortality may vary from beach to beach and from year to year.

5.58. Nonetheless, there are some aspects that are known to be relatively constant on a global level. When reproductive animals are removed from a population, the decline tends to be relatively rapid (e.g., the case of green turtles in Texas, Florida (Witzell, 1994) and Seychelles (Frazier, 1980); when eggs are removed, it takes longer for the decline to manifest itself (e.g., the case of Sarawak (Limpus, 1994)). In some cases, a complex of factors is thought to be related to the decline, but lack of fundamental information, including good baseline data, makes it a challenge to explain many declines in simple, precise terms. This is not to mention that marine and coastal environments are extremely dynamic, and many non-human effects may interact with anthropogenic threats.

5.59. A constant cause for decline, independent of time, is when mortality is greater than recruitment. Mortality and recruitment vary, depending on predation, food availability and quality, habitat quality, and many other factors. Because the life cycle of a sea turtle is complex, and includes large periods of time and large expanses of the planet, mortality can occur at many places and many times during an individual turtle's life. If mortality occurs anytime before reproductive maturity, the individual will not have the opportunity to contribute to the maintenance of the population. In the case of sea turtles, this means that mortality anytime during the first decade or more of pre-reproductive life will eliminate that individual's potential for reproducing, and contributing to recruitment and maintenance of the population. During the period of maturation a sea turtle will have lived in diverse environments, including spending the first two months of its life in a nest on a beach, years in the open ocean, and more years in coastal waters; in each of these environments it will have to evade diverse sources of mortality.

Mr. M. Guinea:

5.60. The conservation status of the world's sea turtles are presented in the IUCN Red data book of threatened animals (IUCN 1996). The hawksbill is critically endangered. Green, loggerhead and olive ridley, Kemp's ridley and leatherback are listed as endangered. The endemic Australian flatback is listed as vulnerable. The status of each species is achieved by nomination of the decline of the nesting population and the nomination of regional threatening processes. Pritchard (1997) states "[t]he IUCN in close cooperation with the Secretariat and Parties to CITES, has now adopted a set of complex numerical and ostensibly objective criteria by which the status category of a species should be deduced...

The criteria incorporate considerations of actual global population numbers, fragmentation of habitat and populations and demonstrable population trends. For the great majority of species, the necessary data are unlikely to be currently available." All marine turtles are included in Appendix I of CITES..." (IUCN, 1995).

5.61. The causes of decline have been the same for all species. Limpus (1997) reviewed the causes of decline in sea turtle numbers in Southeast Asia. Human activities have been nominated as the causative agents in every decline. However, the breeding unit has to be examined to identify what activity or process is responsible for the decline. Trawling may affect some species while egg harvesting and habitat destruction may be more significant for other breeding units. Sea turtles are threatened at all periods of their life. Their critical habitats are also threatened. The nature and level of threat varies for each breeding unit. Threats may be natural and impact on the breeding unit during the nesting season, e.g. Hurricane Pauline destroyed 40 million olive ridley eggs in Mexico (Marine Turtle Newsletter), or affect the morphology of the nesting beach, e.g., storm surges drastically altered the nesting beach at Gahirmatha, India (Satapathy Rajaram, 1997). At least one breeding unit was affected by Cyclone Kathy, which stranded sea turtles on their feeding ground at 1057 km from their rookery (Limpus and Reed, 1985). These unpredictable natural events are less damaging than continuous human utilization.

5.62. Great attention has been given to the decline of modern day sea turtles (Poiner et. al., 1990). Anthropogenic causes are attributable to negative impacts of human activities at any and all stages of the life history of sea turtles and their critical habitats. Direct alteration to the nesting environment by beach modification, through armouring, replenishment, nourishment and their environs by light and waste pollution as well as from recreational pursuits of beach driving and intensive human beach visitation, all have the potential to harm sea turtles, their eggs and/or hatchlings. Introduced and native predators of sea turtles eggs and hatchlings can have significant negative impacts on sea turtle rookeries. Almost every omnivorous vertebrate and many invertebrates within the vicinity of a sea turtle rookery has the potential to be a predator of sea turtle eggs and hatchlings (Carr, 1973). Yet, predation pressures are greatest as the hatchlings cross the shallow coastal waters on their dispersal into the open ocean (Limpus, 1997a).

5.63. Little is known about survivorship of sea turtles in the open sea and through their intermediate years (US National Academy of Sciences, 1990). Most of the interactions between sea turtles and humans are usually to the detriment of the former. Threats include subsistence, artisanal and direct commercial hunting in the vicinity of the nesting beaches and feeding grounds (Frazier, 1980), succumbing to pollution (e.g., petroleum products (Lutcavage et. al., 1997), discarded plastics and fishing gear (Chatto et. al., 1995)), and accidental capture in fishing activities, including bottom set gill nets (Guinea and Chatto, 1992), protective shark meshing (Paterson, 1979), long lines, drift gill nets (Eckert and Sarti, 1997) and shrimp trawls (US National Academy of Sciences, 1990).

5.64. When the above natural and anthropogenic causes of the decline in sea turtle populations are examined few target a single species, although each has the potential to negatively impact on any group of sea turtle species within an area. Natural threats are indiscriminate and may affect any species. Natural predation on eggs and hatchlings is thought to be kept in check by natural balances of predator prey relationships. Predation is so high that it is obvious that a number of terrestrial, marine and avian species depend on sea turtles as a source of protein. Anthropogenic threats to nesting habitats are again indiscriminate and driven more by coastal development, industrialization and the recreational opportunities provided by coastal environments. Direct human exploitation of sea turtle eggs and adults, if unchecked by legislation, will markedly reduce sea turtle numbers even in the absence of trawling activities e.g., Fiji (Guinea, 1993). The eggs of all species are targeted but major industries have been established in the past for green (meat, cartilage and oil), hawksbill (tortoise shell), olive ridley (leather, oil) and leatherback (oil) sea turtles. Incidental capture in fishing gear has the potential to reduce the population levels of some species. Shallow water fisheries in turtle habitats, using large meshed bottom set nets to capture sharks and rays will inevitably capture sea turtles. These nets are traditionally used to capture green (Travis, 1967) and olive ridley (Marquez, 1990) sea turtles.

5.65. Modern shrimp trawling is a relatively new technology. It should be used in conjunction with a number of management tools e.g., exclusion zones, time of trawl activity, vessel size, number of nets, net mesh size and the duration of individual trawls. The trawl fishery is sustained by this reduction of effort while improving the catch of the target species. Bycatch reduction or sorting devices remove unwanted species and objects or alternatively sort fish from prawn species giving a cleaner catch. Trawls of long duration over areas inhabited by benthic feeding sea turtles i.e., loggerhead, olive ridley, Kemp's ridley, flatback and some adult greens or in waters adjacent to their rookeries will capture a proportion of the sea turtles present. TEDs will allow the majority of adult turtles to escape.

5.66. Natural destruction and replacement of nesting beaches occur throughout the tropical region. Native and introduced predators of eggs and hatchlings occur on most rookeries. Coastal development, recreational pursuits and industrialization of the shore are common throughout the nesting range of sea turtles. Shallow water net and trawl fisheries are present throughout the tropical seas. Essentially all of the threats are present in the majority of tropical countries that have sea turtle populations. It is the intensity of those threatening activities, their duration and the subsequent abatement measures, that determine the viability of the sea turtle populations. Abatement measures vary with the socio-economic structure within various countries. The high technology approach to conservation of so-called developed countries appears at odds when dealing with artisanal fishers and trawl fleets of countries that are still developing. The decline of sea turtles has been driven by development of markets for turtles, their eggs, their habitats and other marketable marine species e.g., shrimp.

5.67. Natural threats to the habitat and native predation pressures have been present throughout time. Subsistence utilization of sea turtles has been in operation for some thousands of years by indigenous peoples. Non-indigenous exploitation of sea turtles and their products i.e., eggs, meat, oil, leather and tortoise shell have been operating for some centuries in areas which were close to centres of trade. With a global increase in commercialism, transport and trade, sea turtle breeding units have come under increasing pressures as a commodity. Their habitats are sought for coastal development. Modern fishing techniques place some species that coexist with shrimp at risk. The increase in human demand for tropical marine products and coastal facilities places increasing pressure on the more vulnerable species, such as sea turtles.

Mr. H.-C. Liew:

5.68. On a global scale, IUCN (International Union for the Conservation of Nature) recognises that all sea turtle species are threatened and endangered as all species of sea turtles are listed in CITES Appendix I.404 However, different populations are in different states of health. Some populations have disappeared, some near extinction, some threatened but a few have shown some apparent recovery.

5.69. The factors that are known to cause decline in sea turtle populations are generally similar but differences do exist in terms of importance for different populations i.e. in different parts of the world, and with changing laws and technologies through time. For example, before the widespread use of trawlers and high seas gill-nets, turtle mortality caused by fishing was minimal but laws were not in force then to protect turtles and their products. Hence, there was widespread hunting of turtles for meat, shell and leather. Eggs were also collected extensively for food. Seas were not as polluted then, hence mortality caused by plastics, tar balls, pollutant induced diseases were not as extensive. Similarly, the degree of importance of factors threatening turtles in different parts of the world does differ. Presently in the United States, shrimp trawlers may be the most important threat as the United States has managed with various laws, education and conservation programmes through the years to reduce mortalities caused by killing of turtles and egg harvesting. In Hawaii, the main threats to their green turtle population is not shrimp trawling but the widespread occurrence of the fibriopapilloma disease. In Indonesia, turtle mortalities caused by commercial exploitation of eggs and large scale hunting for the turtle meat markets are significant to be primary causes of population decline.

To Continue With Chapter 5.70


404 Under the new IUCN criteria, sea turtles are designated as follows: Lepidochelys kempii critically endangered; Eretmochelys imbricata critically endangered; Caretta caretta endangered; Chelonia mydas endangered; Lepidochelys olivacea endangered; Dermochelys coriacea endangered; Natator depresus vulnerable. From CTURTLE List (Internet Source). Marydele Donnelly, 10:47 am 02-10-96, IUCN status of sea turtles.