Coastal
Ecosystems Research Foundation
PO Box 122, Port Hardy, BC, Canada V0N 2P0
Please do not quote this document without prior written permission from the authors.
Last modified: November 7th, 1996.
We report two observations of Pacific white-sided dolphins preying on salmon species in the onshore waters of BC.
In August 1994, one of us (WMM) observed a group of Pacific white-sided dolphins fishing near the surface in Johnstone Strait. As the group passed the research vessel (a 16' powerboat, motor off), a single dolphin was observed chasing a single salmonid (Oncorhynchus sp.) under the boat. The dolphin broke off the chase to investigate the boat, allowing the salmon to escape. The fish was about 18 inches long, light in colouration, with small black speckles on its back - more positive identification of species was not possible at the time.
On July 18th, 1996, off Burnett Bay, Queen Charlotte Strait, we observed a group of 20-30 Pacific white-sided dolphins fishing near the surface, occasionally chasing fish out of the water. On one such occasion, while the animals were about 50m away, one dolphin knocked a fish out of the water with its beak, and we were able to tentatively identify the fish as a Coho salmon, Oncorhynchus kisutch. During the same encounter, one of our crew observed a dolphin's head break the surface with a fish in its mouth - it was not possible to identify the species.
We submit that this may be one of the reasons for the increased observation of resident (salmon-eating) killer whale harrassment by Pacific white-sided dolphins.
These reports of predation on salmonids agree with stomach contents analyses carried out by other researchers working in the area.