World Status, Exploitation and Trade - WIDECAST

INTRODUCTIONoutboard motors, nylon nets, and the incentives of a cash economy, but nointrinsic and overriding interest in exercising restraint. Similar factorsapply to the Hawksbill, although the historic use of tortoiseshell must haveled to significant pressure on certain populations, greatest at first onthose within reach of classical civilisations, and later those within thetrade networks of colonial Europe and North America. Whilst the sparsity ofnesting and present general rarity might be expected to hinder furtherexcess harvest, these factors are countered by the continuing strong demandfor tortoiseshell and the widespread collection of eggs.10. No closed-cycle captive breeding of sea turtles has yet occurred,insofar as no turtle conceived in captivity has yet produced a secondgeneration in captive conditions. Ranching, in the sense of rearing incaptivity eggs or young turtles taken from the wild, is technicallyfeasible, but unless strictly controlled, carries a risk, of depleting localturtle populations. It is also feared that the resulting trade maystimulate the illegal trade in turtle products.11. Exploitation, whether for local subsistence use or international trade,demonstrably has the potential seriously to affect turtle populations.Review of the status of Green Turtle and Hawksbill populations suggests thatsubstantial turtle populations will be able to persist only where there isno tradition of exploitation, or where the infrastructure exists to enforcerestrictions on exploitation or the protection of nesting beaches andforaging grounds.12. The Green Turtle Chelonia mydas ( sensu lato ) is a very widespreadspecies, distributed in more than 80 countries in the tropics andsubtropics, many with a large number of nesting colonies. A great manyfemale Green Turtles, on average probably between 100 000 and 200 000, nesteach season; however, most existing significant nesting populations areeither known or suspected to be depleted or in decline. Decline iswell-documented in a minority of cases, but it can be assumed thatutilisation practices which have been shown to deplete certain populationswill have similar effects on other populations, although historical evidenceof decline may be lacking. Seven nesting aggregations are known to havebeen extirpated, virtually all of these were island populations whichdisappeared after human colonisation.13. The Hawksbill Eretmochelys imbricata is a very widespread species,known to nest in at least 60 countries in the tropics and subtropics, butsuspected to nest in more. Available information is incomplete, but itappears that a minimum of between 15 000 and 25 000 females nest annually;no quantitative data are available for many known and suspected nest sites.The world Hawksbill population appears to be far smaller numerically thanthat of the Green Turtle complex. It is possible that the former has alwaysbeen less abundant globally than the latter, but it can be inferred that therelative rarity of the Hawksbill is largely a result of prolongedover-exploitation for eggs and the international tortoiseshell trade.Around half of the known nesting populations are known or suspected to be indecline; in particular, the entire Western Atlantic-Caribbean region isgreatly depleted. Decline is well-substantiated at relatively few sites,but can reasonably be inferred at many others; for many areas, trends areunknown.14. For both Green Turtle and Hawksbill, in virtually every case wheredecline is known or suspected, exploitation is established or implicated as