More about the Research
Foraging Behavior
Research with Dr. Kelly Benoit-Bird
Dr. Benoit-Bird uses underwater sound to observe the foraging behavior of spinner dolphins and benthic fish. Off the islands of Hawaii, spinner dolphins and benthic fish feed on the mesopelagic boundary community. The mesopelagic boundary community is a group ("community") of small fishes, shrimps, and squids that live in the middle of the water column ("mesopelagic") and near islands ("boundary"). . The mesopelagic boundary community moves both vertically (up and down in the water column) and horizontally (inshore and offshore) each day. Using sonar, Dr. Benoit-Bird observed the movements of both the prey and the predators at the same time. Dr. Benoit-Bird showed that the daily movements of the spinner dolphins corresponded with the vertical and horizontal movement of the boundary community.

 

Graph of dolphin and prey movements.
This image shows the daily horizontal movements of the mesopelagic boundary community in black and the spinner dolphins in yellow. The mesopelagic boundary community is found offshore at deep depths (400-700 m) during the day and within 0.5 km of the shore and at shallow depths (0-400 m) at night. The spinner dolphins move offshore at dusk to feed on the mesopelagic boundary community as it rises to shallower depths. They follow the prey as it moves inshore during the night, and follow it offshore after midnight. The spinner dolphins then return to nearshore waters to rest during the day. Image courtesy of Dr. Kelly Benoit-Bird.