beach has yet to result in an increase in size of the primary 

 nesting stock. Should we increase our estimates of 6 to 13 years 

 to maturity for Kemp's ridley, or should we look elsewhere to 

 determine what is happening to the hundreds of thousands of 

 turtles released as hatchlings during the history of beach 

 protection at Rancho Nuevo? Conservation efforts like these 

 should bear fruit but, in the case of the Kemp's ridley, it may 

 take another 10 years before visible evidence is forthcoming as 

 to whether or not management strategies that have been in place 

 for two decades are effective (J. Woody, pers. comm.)' 



A prerequisite and explicit assumption of the following 

 discussion on management research methods is that major sources 

 of turtle losses due to fishing (F) can be identified. The 

 problem is more easily studied in directed fisheries, where 

 knowledge of turtle catch and fishing effort can be used in the 

 estimation of F within a stock. An implicit assumption is the 

 expectation by managers and conservationists that there is some 

 reasonable chance of controlling the fishing effort responsible 

 for identified major losses due to fishing. Complications to 

 such a control arise when stocks cross one or more international 

 boundaries (Dodd 1982). A case in point is that Mexico's efforts 

 to protect Kemp's ridley eggs and nesters on beaches may be 

 severely compromised by incidental capture of this species within 

 the U.S. and Mexican shrimp industries (Hopkins and Richardson 

 1984) . These problems can only be solved through international 

 cooperation among countries having management jurisdiction over 

 the stock (s) in question. 



Life History Approach to Estimating Fishing Mortality 



Stocks exploited directly as eggs, juveniles and adults, as 

 well as taken incidentally in other fisheries, are subject to 

 more than one instantaneous rate of fishing mortality (F) during 

 their life cycle. This statement also probably applies to the 

 instantaneous rate of natural mortality (M) . In attempting to 

 arrive at a framework for measuring these rates, we must divide 

 life history of the species in question into a sequence of fairly 

 homogeneous stages, within which the rates of fishing mortality 

 from specific causes are assumed constant. Just how the life 

 span is divided is a question that must occupy turtle biologists. 

 The question addressed herein is to develop a life history model 

 framework to guide investigations of fishing mortality. Once 

 defined, this framework can become the basis for data collection 

 and parameter estimation within directed fisheries and in sea 

 turtle stocks impacted by incidental takes. This first step in 

 the process is the main purpose of the present communication. 

 However, recommendations presented herein need discussion and 

 clarification by turtle researchers before field studies are 

 planned for further data collection and analysis. 



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