Whales mistaking plastic for prey: A deep-sea danger revealed

Scientists from Duke University conducted research indicating that whales might confuse plastic debris with their natural food. As experts point out, plastic reflects sound similarly to some organisms that whales feed on.

"Their acoustic signatures are similar - and that might be why these animals are inclined to eat plastic instead of - or in addition to - their natural food," emphasized Greg Merrill, the lead author of the study, whose results were published in the journal "Marine Pollution Bulletin."

Whales, such as sperm whales, pygmy sperm whales, or beaked whales, use a highly developed sound reception system to find food in the dark depths of the ocean.

"One hundred percent of tested marine plastic debris have similar or stronger acoustic values compared to those of whale prey," researchers noted.

Thanks to their special anatomical structure, whales send out sounds from formations resembling vocal cords, which are located near their nostrils. This acoustic wave is transmitted into the water by the melon, an oil-filled structure located above the head.

The reflected sounds are then recorded by receptors located in the lower jaw. Subsequent signals are sent to the inner ear and brain, allowing the animal to recognize objects in its environment. This system has been functioning uninterrupted for 25 million years, but the presence of plastic in the oceans disrupts its functioning.

Every year, hundreds of thousands of tonnes of plastic waste enter the oceans, polluting the natural environment. While shopping, using plastic bags or rubber balloons, people don't realize that these objects, once they end up in the seas and oceans, can be mistaken for food by marine mammals.

To determine how whales perceive plastic debris, scientists collected waste from a beach in North Carolina and tested its ultrasound reflections using sonar. "These were plastic bags, balloons, things often found in the stomachs of stranded whales," explained Merrill.

For comparison, researchers also tested real squid and fragments of the cephalopod's beak found in the remains of a sperm whale. The results clearly indicated that plastic often exhibited similar acoustic properties to the whales' actual food.

Although one potential solution to the problem would be to redesign plastics to remove distinct acoustic signatures, the authors are uncertain if this is feasible.

"However, I don't think that's really a viable option, because if fishing nets and lines become invisible, whales will entangle themselves more easily. We don't want them to be unable to recognize them," added Greg Merrill.