Whale watchers witness orca pod hunting blue whale off Bremer Bay

After the reinforcements arrived there were about 16 orcas pursuing the blue whale. (Supplied: Whale Watch WA)

A group of whale watchers have been treated to the rare sight of a pod of orcas chasing a blue whale.

Recorded interactions of this nature between the two species are few and far between — only a handful of successful orca attacks on blue whales have been documented.