Secor and Piccoll: Oceanic migration rates of Morone soxot/l/s, determined by otolith microchemical analysis 





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Figure 6 



X-ray composition maps of srontium (Sr) seen in otolith for two female 

 striped bass ^Morone saxatilis) (17 and 11 years old) collected in 

 Chesapeake Bay in 2000. Arrows demarcate annuli. The "warmer" 

 colors (red, orange) represent regions with higher Sr concentrations 

 whereas the "cooler" colors (yellow, green) represent regions with lower 

 Sr concentrations. Composition maps show the coincidence of stron- 

 tium banding patterns with banding patterns of annuli, indicative of 

 annual anadromous migrations from high to low salinity waters. 



sturgeons; Gross et al., 2002) could in fact be common 

 in some longer-lived species (Rideout et al., 2005). For 

 instance, data-archiving electronic tags inserted on At- 

 lantic bluefin tuna (Thunnus thynnus) have definitively 

 shown that many adults are found outside spawning 

 habitats for an entire annual spawning season (Block 

 et al., 2005). Further evidence is provided by the re- 

 productive behavior of Atlantic cod (Gadus morhua; 



Jorgensen et al., 2006), a species that does not always 

 spawn each year because of density dependence or other 

 environmental limits on its ability to provision gonads. 

 Interestingly, evidence for this can be observed in two 

 female life history transects in our study of striped bass 

 (Fig. 4: ID=295, 300), where no nadir was observed at 

 age seven following a clear nadir at age six (female 

 striped bass typically mature between five and seven 



