I know that Fastloc is much more accurate than Argos, and this problem may cause a lot of big biases. Can you describe why we still should use Argos data?
An interesting study for you would be this: Article Accuracy of ARGOS locations of pinnipeds at sea estimated us...
Costa et al. write in their discussion:" Although Fastloc GPS drastically improves the quality of tracking data of diving marine animals and will facilitate analyses at smaller spatio-temporal scales, the abundance of historic ARGOS tracking records and relative ease of ARGOS tracking (i.e. no recapture requirement) will ensure a continued demand for analytical approaches using these data. "