The objective of this approach is to develop a life table 

 for sea turtles whereby life history is partitioned into 

 meaningful phases (of non-uniform duration) within which 

 impact (s) of fishing mortality can be determined. This approach 

 to identifying management research needs assumes that defining 

 impacts of harvesting on stock replenishment is the key question 

 to consider for overexploited and potentially endangered 

 resources such as sea turtles. Questions related to optimal 

 yield should be deferred until such time as stocks recover to the 

 point where they can be safely exploited, if ever . A second 

 overriding assumption is that characterizing impacts of turtle 

 harvest by estimating fishing mortality (F) assumes that there 

 exists a real potential for management (i.e., fishing effort is 

 or can be controlled) . Complete prohibitions on fishing and 

 incidental take are two extreme kinds of management controls of 

 fishing effort, but more moderate controls are also possible. 



Partitionincf sea turtle life history ; All sea turtle life 

 history stages subject to fishing mortality are addressed herein; 

 but, by necessity, females are the only component considered for 

 the breeding population sector. At any one stage (i) of the life 

 cycle the various causes of mortality expressed as exponential 

 rates are additive (i.e., total mortality equals fishing 

 mortality plus natural mortality, or Z^ = F^ + Mj^) , but this does 

 not apply to comparable mortality rates experienced by successive 

 stages in the life history. For the sake of argument, sea turtle 

 life histories are divided into arbitrary stages i = 1, 2, 3..k 

 (Fig. 1) , to each of which we attribute annual mortality rates 

 (Fi + M^j and duration (t^, where t is measured in years) as 

 follows: 



Stage Description Parameters 



I Egg survival from oviposition to Fj, Mj, Atj 

 hatching 



II Migration of hatchlings from nest Fjj, Mjj, Atjj 

 to beyond littoral zone 



III 'Juvenile' stage (until sexual Fm, Mm, 

 maturity) 



Atiii 



IV* Migration of adults (females only) Fjv/ ^IV/ ^^IV 



V Time spent at sea as mature adults Fy/ My/ Aty 



* It is desirable to distinguish repeated egg laying events (in 

 the life history model) for organisms that show multiple 

 nestings. This is achieved by a superscript — e.g., Fjy, denoting 

 fishing mortality experienced during the first egg laying 

 migration. 



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