Diel and seasonal patterns of spotted gar movement and habitat use in the lower Atchafalaya River basin, Louisiana

We used radiotelemetry to determine diel and seasonal movements, habitat us e, and home range behavior of 37 adult spotted gars Lepisosteus oculatus in the Atchafalaya River basin, Louisiana. The Atchafalaya River exhibits a d istinct spring flood pulse each year, inundating a 3,640-km(2) floodplain t hat includes a complex network of canals, bayous, and lakes. During non-flo od months, diel locations of 27 fish recorded at 2-h intervals (median = 24 locations/fish) indicated that most spotted gars were shoreline oriented ( P < 0.0001), preferred submerged branches as cover and avoided areas of exp osed bank (P < 0.0001). Median spotted gar movement rates were higher durin g summer (40.4 m/h) than fall-winter(15.1 m/h), and during both seasons,rat e of movement and percentage of home range used were significantly greater at night during dawn, day, or dusk periods (P < 0.03). Increased nocturnal activity appeared to be related to feeding periodicity, as a substantially greater proportion (70%) of spotted gars collected at night (N = 30) contai ned food compared with dawn, day, and dusk samples (29%; N = 90). Seasonal movement studies (twice-weekly locations; N = 37 fish) indicated that spott ed gar activity increased as water temperature and river stage rose in the spring,resulting in greater median movement rates (130.1 mid) and home rang es (265.1 ha) than during fall-winter (35.8 mid; 6.2 ha) and summer (34.6 m id; 10.5 ha). Spotted gar home ranges established during the hood pulse typ ically included large areas of inundated floodplain, which provided extensi ve areas of suitable spawning and nursery habitat.