Biologists at the Vancouver Aquarium are keen to find out how to prevent dolphins from getting trapped in fishing nets and colliding with ocean debris.

Sherri Refcio, dolphin coordinator, Vancouver Aquarium, said, "Every dolphin is a little bit different. Some dolphins are very comfortable having them on their bodies. Some dolphins were a little uncomfortable having them on their bodies and will try to swim away or try and take them off. But I'd say all of them are pretty comfortable with wearing at least one of them on their eye."

With their eyes covered, dolphins can listen to sound cues that help them find their way around by using passive listening.

The scientists want to discover how dolphins choose to use echolocation, or passive listening.

Further experiments will have the dolphins swim through an obstacle field of benign objects that won't hurt the animals, such as nets, ropes and lines that are suspended in the water.

The final stage of the study will have the dolphins chasing fish with eye cups on. Biologists hope to be able to determine if the animals use echolocation when pursuing their prey without being able to see.

(CCTV December 15, 2008)