Diel Movement Patterns of the Hawaiian Stingray, Dasyatis Lata: Implications for Ecological Interactions between Sympatric Elasmobranch Species

The Hawaiian stingray, Dasyatis lata , is a common benthic elasmobranch in nearshore Hawaiian waters. Acoustic telemetry was used to track the movements of seven rays in Kaneohe Bay, Oahu, Hawaii. Rays were tracked continuously over 31–74 h periods. Geographical movements were analyzed to determine space utilization and rate of movement. Rays were found to utilize significantly larger activity spaces at night (0.83±0.70 km ² ) (mean±SD) than during the day (0.12±0.15 km ² ). Mean total activity space for rays tracked was 1.32±0.75 km ² . Rates of movement were also significantly higher at night (0.34±0.30 km h ^-1 ) than during the day (0.15±0.22 km h ^-1 ). Average straight-line swimming speed was 0.64±0.16 km h ^-1 , with a maximum observed swimming speed of 1.9 km h ^-1 . Tidal stage had no effect on rate of movement. Comparison with previously published data on juvenile scalloped hammerhead sharks, Sphyrna lewini , in Kaneohe Bay revealed a high degree of overlap in habitat use and time of activity, suggesting possible ecological interactions between these two species.