Radio-tracking Interval Effects on the Accuracy of Diel Scale Crayfish Movement Variables

Abstract

The effect of increasing the interval between radio-tracking fixes above 1 h was examined for estimates of the diel activity, diel mobility, and diel range of the Murray River crayfish, Euastacus armatus. Estimates of these diel variables were determined by radio-tracking six individuals at intervals of 1 h for three diel periods. These data were then sub-sampled to simulate radio-tracking at intervals of 2 h, 3 h, 4 h and 6 h. Our perception of diel activity was altered as a consequence of different sub-sampling intervals, and variation in activity over the diel period was lost as tracking interval was increased. Both mean diel mobility and mean diel range decreased linearly with less frequent radio-tracking. A shift from 1 h to 6 h tracking corresponded to 49% and 55% reduction in estimated diel mobility and diel range, respectively. However, we suggest that these trade-offs between information gain and radio-tracking effort be viewed in the context of a comprehensive understanding of home-range across multiple seasons with a view to conserving this species. [Keywords.- diel activity; diel mobility; diel range; Euastacus; Radio-telemetry; temporal resolution].