Mobility and home-range use of Atlantic salmon parr over short time scales

This study performed in the Patapédia River (Québec, Gaspésie) was designed to examine the space utilization and mobility patterns of individual Atlantic salmon parr over short time scales with frequent detections of position. In August 2004, n = 7 radio-tagged Atlantic salmon parr were located every 20 min during 10 tracking periods chosen to take into account the dawn, day, dusk and night periods. Parr showed important inter individual variability in space utilization and mobility patterns, occupying large home ranges (123 to 5602 m2) and sometimes migrating 2 km upstream in the river. No differences were observed in the mean distance travelled among the four daily periods by individual fish, but the estimated home ranges utilized during the four daily periods overlapped only partially, demonstrating that parr partly occupy different areas of the river during different parts of the daily cycle. The results suggest that an intense survey on a small number of fish may contribute to a complementary comprehension of space utilization and mobility patterns of Atlantic salmon parr when viewed in association with results from studies surveying larger number of fish at lower frequency.