Influence of Time Interval on Estimations of Movement and Habitat Use

Abstract

Although biotelemetry has been widely used in fisheries science, the standardization of methods is uncommon. Researchers often use more than one time interval (frequency of recording locations) in a study, and different researchers frequently use different time intervals. There is a paucity of information describing the relationship between time interval used and movement observed or the proportion of time associated with habitat type. The objectives of this study were to evaluate the effects of varying time intervals on fine-scale (i.e., minutes-to-hours) diel movement and habitat use by spotted bass Micropterus punctulatus. To evaluate such effects, we tracked spotted bass (n = 11) every 15 min for a 24-h period. Using these data we simulated tracking at 30-min, 1-h, and 2-h intervals. The mean percent error of time interval simulations for total daily movement varied from 24.3% to 64.3% for 30-min and 2-h intervals, respectively. Loss of movement information (i.e., detecting less movement with simulated time intervals compared with the original data set) increased with increasing time intervals, and the 2-h interval poorly estimated diel movement. Conversely, habitat use was well-represented by each time interval. These results illustrate the importance of standardizing the use of time intervals and the need to consider time intervals when comparing results among biotelemetry studies.