Harbour porpoises at the tidal buffet

By Alana Phillips

In the last week, we’ve received a few sightings of large groups of harbour porpoise south of Vancouver. As many as 30-40 harbour porpoise have been seen, usually in strong tidal eddies where rivers and streams enter the Strait of Georgia. Harbour porpoise are known for being more solitary animals, so why are they all getting together?

“We believe they are foraging on small schooling fish”, says Anna Hall, a harbour porpoise researcher at the University of British Columbia. Strong tides in the spring and fall create these tidal eddies which concentrate their prey, resulting in a buffet for harbour porpoise and seabirds. Harbour porpoise are thought to feed on herring, eelpouts and squid, although their prey can vary throughout the year.

Although they are occasionally seen in large numbers in the spring, harbour porpoise have been listed at Special Concern under the Species At Risk Act (SARA). As their name suggests, harbour porpoise prefer shallow waters close to shore, but this habitat is becoming increasingly urbanized and contaminated along our coastline, particularly around Vancouver and Victoria.

Harbour porpoise are frequently entangled in nets and other fishing gear, and are especially vulnerable to disturbance. As the levels of vessel traffic and underwater noise increase in our area, harbour porpoise will be forced out of many of their natural feeding habitats, and may find it difficult to find space they need to rest, find mates and raise their young.

Every year, a number of harbour porpoise strand along our coastline, and researchers want to know why they’re dying. If you see a dead harbour porpoise, please call the DFO Marine Mammal Incident hotline at 1-800-465-4336.

If you are lucky enough to encounter harbour porpoise in the wild, please keep your distance and follow the Be Whale Wise guidelines. And please let us know what you saw! Your sightings of harbour porpoise are important as they give us more information that we can use to help protect these elusive and sensitive creatures.