318 



Fishery Bulletin 104(2) 



subsequent high uncertainty in the estimation of vital 

 rates of many marine species, including elasmobranchs, 

 is testimony to the fact that the accumulation of life 

 history information should be a priority to biologists, 

 fisheries scientists, and resource managers. Results 

 from the models presented here could be used to hy- 

 pothesize life history values in areas currently lacking 

 information and thus be tested with further sampling 

 in those areas. It is also hoped that the approach of- 

 fered here may indicate areas where sampling may not 

 be sufficient, as denoted by departures from the general 

 model trend. Targeted sampling in that area would help 

 resolve whether the departure is from a true area effect 

 or species effect. As more data is gathered, it will be 

 possible to explore other factors — such as temperature 

 and guilds (e.g., coastal versus oceanic) — in the model 

 structure. 



Once steps are made to further resolve the species 

 and area effects, one may start to ask questions re- 

 garding the cause of particular area effects. Poten- 

 tial mechanisms of true coarse-scale gradation of life 

 history traits may be contained within the general- 

 ized characteristics of oceanic zoogeographic realms 

 (Longhurst, 1998b), although a slightly less abstract 

 mechanism could be found in the physical forcing events 

 that characterize regions in the northern and southern 

 hemisphere. Although both hemispheres demonstrate 

 similar large-scale current and wind patterns, physi- 

 cal forcing events tend to be stronger in the northern 

 hemisphere (Trenberth et al., 19981. Because this study 

 offers coarse area designations to intraspecific life his- 

 tory variation, it is most likely a product of some macro- 

 scale characteristics of each region. Attention should 

 therefore be directed towards large-scale characteris- 

 tics of each region to explain these patterns, although 

 small-scale dynamics are important for understanding 

 each population's specific response to local environmen- 

 tal conditions (i.e., countergradient variation in growth 

 rates [Conover, 1990; Conover and Present, 1990]). 



It is becoming increasingly important to be able to 

 assess fish stocks with minimal data. By combining 

 genetic data revealing differing levels of intraspecific 

 population substructure with the increasing number of 

 studies demonstrating localized adaptations and plas- 

 ticity in population parameters, it is apparent that 

 intraspecific spatial differences must be considered in 

 species management (Aviso, 2000; Roff, 2002). Although 

 the predictive power of this study may currently be 

 weak because of low sample sizes, it offers a method to 

 quantify potential spatial patterning in intraspecific 

 life history traits that may allow responsible manage- 

 ment of regionally data-poor species, and it may help 

 frame future sampling protocols and studies of spatial 

 patterns in life history traits. 



Acknowledgments 



I am grateful to Andre Punt, Joe Bizzarro, Gavin Fay, 

 and Arni Magnusson for their many important comments 



regarding model structure and data use. I also thank 

 Kristin Benshoof, Marilyn Cope, and three anonymous 

 reviewers who contributed insightful comments that 

 improved the presentation and clarity of this note. 



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