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Fishery Bulletin 105(1) 



is based on a simple sensitivity analysis conducted by 

 testing alternative stock structure hypotheses. When 

 plausible hypotheses are generated from the cumulated 

 knowledge on the biology and fisheries of the species, 

 the effect of these hypotheses on the assessment results 

 can be studied. However, it is also important to consider 

 a range of alternative hypotheses so that they produce 

 significantly different results in the assessment, in refer- 

 ence to the base case. The wide range of results allows 

 us to discern the level of migration that is of concern 

 for assessment purposes and shows the level of migra- 

 tion that is not likely to be realistic, given the available 

 catch and effort data. However, several other sources of 



uncertainty should be taken into account at this stage. 

 The analysis could be extended to future biomass pro- 

 jections under different management strategies in order 

 to indicate those management strategies that are more 

 robust to violation of stock structure assumptions. This 

 kind of study should run parallel to other studies where 

 additional sources of uncertainty (e.g., in biological 

 parameters or fishery data) are quantified because this 

 approach would show their relative importance so that 

 research could be prioritized with the goal of providing 

 improved information on stock status. 



In the case of Atlantic albacore, recent genetic stud- 

 ies indicate that, either the limit between both popula- 



