“In this case, the motor boats spell death for the young fish,” said Simpson. He thinks two factors - distraction and stress - are the most likely reason, with both probably playing a role.
The motor noise distracts the damselfish, so they take less notice of the dottybacks. “Under the cloak of noise, the predator is winning,” Simpson said. The stress caused by the noise alters the damselfishes behaviour, he said: “It can cause fish to respond [to attacks] in the wrong ways. If you think of people, when we are stressed we often do crazy things.”