As I see it, our main decision in addressing the question of 

 management options at this point is this: do we continue to use 

 implicit, unspecified population models in making management 

 decisions, or do we begin to use explicit, clearly-specified 

 population models in attempting to make management decisions? 



The formal models require explicit quantitative input 

 values. In order to make mathematical computer models, 

 assumptions must be clarified and stated. Investigators in this 

 field are usually required to state just how the input values 

 were derived so that others who disagree can modify the scheme to 

 incorporate their own methods of assessing the quantitative 

 biology of the species. 



Incorporating all known information into a complete model 

 makes it possible to conduct sensitivity analyses to determine 

 how sensitive predictions are to inaccurate or unavailable data. 

 The models generate testable hypotheses in the best scientific 

 tradition. And finally, new information is easily added to such 

 a model. 



In short, explicitly constructed mathematical models serve 

 to clarify our thinking. As you can imagine, the explicitness of 

 the formal models and the requirement that we divulge our 

 thoughts about how things fit together and where all the values 

 come from makes them easy to criticize (and easier to correct, I 

 might add) . But clear, constructive criticism is not to be 

 shunned or hidden. It is the strength of science, and we should 

 welcome the scrutiny of others. 



On the other hand, the implicitness and subjectivity of the 

 current informal models make them more difficult to criticize in 

 any productive way, since builders of this type of model do not 

 have to tell us the specific assumptions they make or the 

 particular values, if any, that they place into the underlying 

 mathematical relationships upon which such models rest. 



Two very explicit, carefully constructed formal models of 

 the new type are available. One has been used to carry out stock 

 assessment based on nesting female surveys. K. Eckert provided a 

 modification of the classical Jolley-Sever method for population 

 estimation specifically to incorporate the peculiarities and 

 irregularities of sea turtle reproductive behavior. The other 

 model has been used to assess the probable effects of various 

 management options (hatcheries, TEDs, protecting adult females, 

 protecting subadults, etc.) on a loggerhead population. D. 

 Grouse (also here on the panel) has provided a modification of 

 the classical model of population dynamics. Grouse's model will 

 appear soon in the scientific journal Ecology , after having 

 received constructive critical review by some of the leading 

 ecologists in North America, and I believe that Eckert is 



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