World Status, Exploitation and Trade - WIDECAST

SEYCHELLESNesting numbers Two marine turtle field biologists have spent extendedperiods in the Seychelles: Frazier in 1972-1973 and Mortimer in 1981-1983;both published reviews in 1984 of turtles in the Seychelles, largelyreflecting their own field research. For comparative purposes, nestingestimates of both authors are given in Table 173 (Mortimer's data are basedon more field time and may thus be generally more representative).Mortimer (1984: p. 16) characterises the C. mydas population as follows:Granitic Islands - virtually extinct; Amirantes - fairly rare; southernislands - numerous (on some).Trends In nesting numbers Direct evidence is sparse, but trade data,with verbal and written reports, strongly suggest a general decline innesting numbers, dating in places from the middle of the last century. BothFrazier (1984, Fig. 14) and Mortimer (1984, Fig. 19) have graphed the annualweight of calipee exported (converted into approximate turtle-equivalents)between 1907 and 1968/1970 (data first compiled by Stoddart, 1976). Thelate 1960s export figure is around 20% of the late 1900s figure, with arather steady decline throughout the intervening years (with two cleartroughs corresponding to World War I and World War II). This decline inexport volumes is lilcely to represent a parallel decline in C. mydaspopulation levels, due to over-exploitation.An 1846 source, cited by Mortimer (1984: p. 17), reported that C. mydas werecommon at the time of his writing but had formerly been more abundant.Turtles were regularly found (and captured) around Praslin and Mah^ 20 yearsago, but are now seen there only rarely. While the species appears to havedeclined around the Granitic Islands, the former intensity of nesting in thearea is not known. According to Hornell (1927), the species had been"fairly numerous" in the northern islands, but always much less abundantthan in the south; the species had virtually deserted the Mah^ group by the1920s.South of the Granitic Seychelles, historical records (cited in Mortimer,1984) suggest that large numbers of C. mydas nested in the Amirantes. Aship's log reports that 32 females were taken in one night in 1770, probablyon Poivre; only 5-10 are estimated to nest in one year on Poivre at present;but the island manager reports that 16 years ago about twice as many werenesting. On Coetivy, eight turtles were taken in one night in 1788 and SIin five or six days; at present there are an estimated 30-50 in one year(Mortimer, 1984). The species was still numerous in the 1920s, but lesscommon than at the turn of the century (Hornell, 1927).Numbers appear to have declined also in the southern islands; the C. mydascommercial harvest for calipee appears to have been largely based in thisgroup, and to have become intense at the time of the colonisation of Aldabraand Assumption in 1906-1907 (Hornell, 1927). On Assumption, which formerlyrivalled Aldabra in C. mydas nesting numbers, 200 turtles were seen to benesting on a single night in the mid-1900s, and "at a rather earlier date"up to 300 were taken in a night (sources cited in Hornell, 1927). The dailyharvest around 1906 was some 150 turtles, but the catch was reduced to 5-6per day by 1916 (equivalent to about 2000 annually), and to about 1100 peryear around 1925 (sources cited in Stoddart, 1976). More recently,estimated numbers nesting per year were 100 in the early 1970s (Frazier,1984), and 160-240 in the early 1980s (Mortimer, 1984). In other words, thenumber of females nesting in a year at present is approximately equal to thenumbers that nested in one night at the turn of the century. Althoughturtles cropped in former times were taken in part by harpoon at sea (and4S6