| Life history theory predicts that populations with different growth trajectories are likely to differ in demographic parameters. In Alaska there are three sea otter stocks that have different population status. To determine if stocks differed in demographic rate, this study developed a technique to estimate parous status and average age at first reproduction (aAFR) from premolar cementum annuli width measurements. Subsequently, we compare aAFR and reproductive rates (RR) among spatially and temporally isolated sea otter stocks. Spatial comparisons revealed that aAFR was oldest in the most stable sea otter stock, while the temporal comparison revealed that aAFR was younger in southwest Alaska when the stock was declining, as compared to when it was stable. RR did not differ in space or time. These findings support the hypothesis that southwest Alaska sea otters are declining due to top down effects, and demonstrate the utility of demographic parameters in wildlife population management. |
