Even if one takes the pessimistic position that an average female 

 manages to lay only a single clutch (ca. 100 eggs) , pre-breeding 

 attrition would still be 98%. More sophisticated models, 

 incorporating more data but also more assumptions, have been 

 elaborated for various species in various parts of the world 

 (review in Frazer 1986) . All of these give >98% mortality from 

 egg to maturity; in fact most give >99.5%. 



Much of this attrition takes place on the beaches. One may 

 quibble about some of the details and limitations in the 

 quantitative studies outlined above, but they all show high 

 mortality at these initial stages in the life cycle. In the 

 particular examples discussed above, 63.5% is the highest 

 suirvival to hatching to be found. Most of the survival rates are 

 <50% with some <10% (Fig. 1, Tables 1-3) . This means that by 

 protecting eggs (and hatchlings) on the beach one can exert some 

 leverage on the population. Exactly how much will depend on the 

 complex interactions between the various sources of mortality. 

 Saving 2 0% of the eggs from tides provides more for predators on 

 the beach. Putting more hatchlings into the water provides more 

 food for the fishes. But no reason exists to assume that 

 predation from such sources would become proportionally worse the 

 more eggs and hatchlings were being produced (one assumes one is 

 operating at a level past that where a specific search image 

 could be activated) . Therefore, the very high levels of natural 

 mortality which at first may seem yet one more obstacle to 

 overcome in conserving sea turtles, in fact, offer a splendid 

 opportunity for increasing turtle populations. Exactly how such 

 an opportunity should be used will depend on the levels of 

 unnatural mortality and one's conservation philosophy. 



Natural and Unnatural Mortality and Options for Utilization 



Natural and unnatural mortality (e.g., incidental catch), 

 have to be considered together in formulating management 

 policies. If a particular population is at perilously low 

 levels, and subject to high unnatural mortality (e.g., Kemp's 

 ridley, incidental catch) every effort should be used to reduce 

 natural mortality until unnatural mortality can be attenuated. 

 But there are also turtle populations that are clearly not on 

 their last stand. Thousands of green turtles nest each year in 

 Surinam and Costa Rica and the numbers are not declining (see 

 Mrosovsky 1983b). Olive ridleys in Costa Rica destroy vast 

 numbers of eggs of their own species. In India at Gahirmatha, 

 Orissa, when a ridley arribada came ashore on the same stretch of 

 beach used by the previous arribada "the beach became littered 

 with broken shells and dead hatchlings" (Mohanty-Hejmadi 1987) . 

 The same thing occurred on another occasion and the beach 

 "resembled a turtle graveyard" (Bhaskar 1984). 



What if anything, should one do in such cases about natural 

 mortality? At the last WATS meeting, a distinguished 



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