Bubble-Net Feeding Among the Humpback Whales in the Great Bear Rainforest

Humpback whales surge to the surface
Humpback whales surge to the surface

Recently, I was asked about the story behind the photo in my website’s banner.

These are humpback whales and what they’re doing is really cool. It’s called “cooperative bubble-net feeding.”

Here’s how it happens, as I understand it. A small group of humpbacks come together and they begin cruising along shorelines to locate schools of small fish, most commonly herring. When a school is located, the whales move swiftly to corral the fish into a more compact ball. This enables the whales to swallow more in a gulp.

Humpback whales preparing to dive
Humpback whales preparing to dive

So how does a humpback corral the fish? First they take a few deep breaths, then they arch their backs and flip their tails signalling a deep dive.

Humpback whales Diving
Humpback whales diving

* Please note that the tour boat is further away from the whales than what it appears due to the compression of distance caused by using a long lens. The image was also slightly cropped to create a stronger composition.

For a while, there is nothing. Only stillness on the water’s surface. But the gulls wheeling around expectantly suggest something big could be coming. You can almost feel it.

Then, they begin to form. Subtly at first. Almost imperceptible, but very rapidly building into what appears to be a perfect ring of bubbles breaking the surface calm.

What’s happening below is really, really neat. As the whales dive, they blow bubbles in an ever-tightening circle below the increasingly panicky fish.  While diving, they also emit a very particular high-pitched call. In their fright to avoid the threat coming from below, the small fish move upwards towards the surface. Some can even be seen leaping out of the water to get as far away as possible. Many of these end up going down the throats of daring gulls that dart in to pick them off.

I wish I had photos of this action. It’s wild. Next year, I’ll be ready.

Anyhow, you can pretty much guess what’s coming next. Yep, a major eruption!

Humpback whales and gulls
Humpback whales and gulls

The whales have come up through the middle of the bubble-net and with their mouths open. With this mighty lunge, they gulp down hundreds of fish along with vast quantities of sea water. Pleats of skin and blubber hanging of the lower mandible unfold to accommodate.

This is truly an awesome spectacle to witness.

But as if this wasn’t amazing enough. Cooperative bubble-net feeding, it turns out, is a learned behaviour. It first appeared among humpback whales in South East Alaska in the mid-1980s and has been spreading southwards. I don’t know yet how far south it has spread, but the tactic was certainly in high use among the humpbacks seen in the Great Bear Rainforest, especially in Whale Channel. What this spread demonstrates is a form of cultural diffusion and the remarkable intelligence of these animals and their kind.

To learn more about humpback whales, I encourage you to check out the work done by the Marine Education and Research Society , For Whales.Org and BC Whales.Org