By Stephen Beech
Killer whales team up with dolphins to hunt salmon, reveals new research.
The apex predators, also known as orca, have been caught on camera for the first time hunting with Pacific white-sided dolphins in seas off British Columbia, Canada.
The two iconic marine mammal species were also spotted sharing fish scraps after making a kill, according to a study published in the journal Scientific Reports.
The findings represent the first documented recording of cooperative hunting between orca and dolphins, according to the Canadian research team.
Study author Dr. Sarah Fortune said: “Pacific white-sided dolphins are often seen hunting along the coastline of British Columbia within meters of orca.
“Although orca frequently share their prey captures with pod members, they hunt independently.
“As the two species have not shown signs of fighting or avoiding each other, researchers have speculated that this may be due to them cooperating rather than competing for food.”
Dr. Fortune, an Assistant Professor in the department of oceanography at Dalhousie University in Canada, and her colleagues investigated hunting patterns of nine northern resident orca and their interactions with Pacific white-sided dolphins around Vancouver Island in August 2020.
They used movement data, underwater footage, acoustic recordings, and aerial drone footage to establish how the orca moved and hunted.
The team observed 25 instances of orca changing course after encountering dolphins to follow them on foraging dives.
They say that may be due to orcas dampening their own noises to listen out for dolphin echolocations, which may help orca to detect Chinook salmon, prey too large for dolphins to capture and swallow whole.
The researchers recorded eight instances of orca catching, eating, and sharing Chinook salmon with other orca, with dolphins present on four of those instances.
Dr. Fortune said: “On one occasion the dolphins scavenged the remains of an adult Chinook salmon broken into scraps small enough for them to eat by the orca.”
The researchers say that was an act of prey sharing.
Dr. Fortune added: “The presence of local orca may offer dolphins protection from other orca pods passing through the area, while their interactions may help orca locate salmon more easily while providing an opportunity for dolphins to feed on scraps.”
However, she said more research is needed to investigate that suggestion.
