IMIS

The goal of this work was to monitor occurrence of acoustically active cetaceans in the Southern California Bight and develop predictive models of habitat. The data presented here are based on echolocation clicks of Risso's dolphins and Pacific white-sided dolphins. High-frequency Acoustic Recording Packages (HARPs) were deployed at six locations in the Southern California Bight between August 2005 and January 2008 to examine diel, seasonal, and annual patterns of occurrence and distribution. Long term spectral averages (LTSAs) were examined by eye for the presence of echolocation click bouts from Risso's dolphins and Pacific white-sided dolphins. Click bouts were identified to species by a trained analyst based on their spectral characteristics (described in Soldevilla et al. 2008). Observations represent presence in one-hour time bins (#obs) and are quantified as the number of one-minute time bins with clicks present. Two click types, A and B, were identified for Pacific white-sided dolphins, which show spatial and temporal segregation in occurrence. HARP recording schedules varied across deployments and include continuous recording, 1/2, 1/3, and 1/4 duty cycles in which 5 minutes were recorded followed by 5, 10, and 15 minutes off, respectively. Effort data is also available in one-hour time bins and includes the number of minutes with recording effort per hour. Times are in GMT. These data were analyzed by Melissa Soldevilla. This research project was funded by F. Stone and E. Young through CNO-N45.