Fishing Technique in Dolphins Passed From Mother to Daughter

The latest study conducted by the researchers at the University at Wales , solves the mystery behind why just five percent of the dolphins in Shark Bay use sponges for hunting, and why this rare hunting technique is absent in the other dolphin population.

It was in 1984 that it was noticed how the Dolphins in Shark Bay, Western Australia carried sponges on their snouts. It is assumed that these snouts help them protect their sensitive noses as they hunt along the rock sea bed, dislodging fish and crustaceans.

And the latest study has revealed that this technique of using sponges to help catch fish that is a rare hunting technique is passed from mothers to daughters for generations.

Dr Anna Kopps from the UNSW Evolution and Ecology Research Centre spent four years studying the dolphins of Shark Bay observing this unusual behaviour.

With the help of computing modeling of behavior and genetics, Koops estimated how long the sponging behavior has been going on in Shark Bay.

According to Koops, this cultural behaviour seems to be passed down only along maternal lines i.e from mother dolphin to daughter dolphin. This is absent in the male dolphins as they socialise in packs to hunt for fish.

"What they do is unique among dolphins," Kopps said. "It appears that this technique of using a sponge has been passed on from mother to daughter dolphin for around eight generations.

"We were interested in how long it has been passed on because it is rare for an animal species to pass learned tool use behaviour through several generations."

The lifespan of a dolphin extends to up to 40 years. Dolphin offspring are dependent on their mothers for about four years, giving them ample time to observe and learn survival techniques.

"We don't know if it's teaching or other forms of learning," Kopps said. 

At the end the researcher concluded saying sponging among dolphins could have stemmed from one female dolphin that started doing it at least 180 years ago and passed the foraging technique down through her female descendants.

The detail of this study was published in the journal Animal Behavior.