We are currently conducting gill-net objects and pinger experiments each day at Sea World with harbor seals and Commerson's dolphins. We use gill-net fragments mounted on a plastic frame which we lower into the pool. The nets are specially designed so the study animals don't become accidentally caught and injured.
Commerson's dolphins echolocate at such high frequencies that we cannot hear their sounds with our human ears. So we have to record their sounds through a device that lowers the frequency to something we can hear and record. We then analyze the tapes to see how echolocation and communication sounds change in the presence of gill nets.
Each day, after our subject animals have been fed, we monitor the animals' behavior with video cameras and hydrophones for one hour. This is called baseline data collection, and it shows us how the animals behave normally, when there is no net or pinger present.
We then place one of our three gill-net objects into the pool, one of which has a pinger.
Next, we observe and record the animals' behavior and
sounds for one to two hours. After the experiment is
over, we take the video and audio tapes back to the
laboratory and analyze how often the different species
approached and touched the net objects.
We will soon be adding California sea lions and bottlenose dolphins to the study. Eventually our work will encompass many species and will take us to other Sea World parks in the United States.
Many questions need to be answered before we can attempt to solve marine mammal entanglement problems. But we have the chance to test many theories in our laboratory setting. The valuable information we gain through the Novel Objects Project can then be used to reduce entanglements. We are very excited about our research.