The seagulls give it away every time. All eyes aboard the Coastal Explorer are tracing their movements because these wily birds know—moments before we do—where the humpback whales will emerge in their amazingly synchronous behavior called bubble-net feeding. My eyes  shoot across the water as the birds congregate. Within seconds, the open mouths of six whales appear together.

“Oh my God!” I exclaim as everyone on the boat erupts in similar awe. These ordinarily solitary humpback have just coordinated their efforts to make their herring feeding as efficient as possible. And recently, they’re engaging in this behavior in the waters surrounding Kenai Fjords National Park more reliably, particularly from mid-June to mid-July, according to our seasoned captain, Mark Lindstrom.

“And here come some tails,” he says over the loudspeaker. As if on cue, I watch a fluke emerge and re-descend balletically into the water. Four more follow in succession. In between bubble-net feeding, the whales also blow loudly and show the dark arc of their glossy bodies. Two whales further astonish us by launching their tonnage nearly out of the water one after the other. They’re truly putting on a show, from our perspective. From theirs, they’re just “making their living,” as Lindstrom says.

Last June, I took an eight-hour cruise along much of this national park coastline from Seward, Alaska, to the Northwestern glacier and back with Kenai Fjord Tours. From a deck is an immersive means to experience the magnificence of this 607,805-acre national park in south central Alaska, much of which is covered by snow and ice.

Before we even spied a whale, Lindstrom welcomed us to “one of the most wild and pristine parks set aside for future generations” because there’s no ranger to do so. Lindstrom wants his visitors to understand that they may, in the future, have to make tough decisions about whether to preserve such wildlife-rich park lands and waters or exploit their other valuable resources.

A breaching humpback whale at Kenai Fjords National Park/Kenai Fjords Tours

Since 1989, when the Exxon Valdez ran aground and spilled 11 million gallons of oil into Prince William Sound, the herring population hereabouts has struggled and never completely rebounded. Scientists have theories but aren’t entirely sure why, says Scott Pegau of the Prince William Sound Science Center, which is partly funded by the Exxon Valdez settlement. The herring have faced other harmful factors, including a 2014-16 West Coast warming phenomenon called “the blob,” which led to a crash in both the herring population and a wrenching humpback die-off. Herring also faced a disease called viral hemorrhagic septicemia.

But lately, herring have had some better years which, in turn, can benefit charismatic megafauna, like humpback whales. Sherri Dressel, a statewide herring fisheries scientist with the Alaska Department of Fish and Game, monitors statewide herring trends.

In 2019, “we saw increases across the Gulf of Alaska that, for some stocks, were the largest that we've ever seen for the number of age three fish,” she tells me. “It was dramatic.” Those assessments compare with herring records going back to the '70s and '80s. Age three is significant because that’s usually the first age that herring spawn and spawning populations are most easily assessed.

In the spring and fall, herring tend to aggregate while spawning or overwintering, making them easier feeding, explains John Moran, a research fisheries biologist with the National Oceanic and Atmospheric Administration. “But in the summer, the herring [and other prey, like krill] are more spread out. So this bubble-netting is a way to concentrate them.”

It’s an important survival tool for hungry humpbacks whose food supplies are not always predictable or stable.

As they swim in circles below the water, the bubbles the humpbacks release from their blowholes act as a visual barrier for the herring, but the fish can swim through them, Moran explains. There's also one whale outside the net that's “making noise between a scream and a moan.” The bubbles attenuate the sound waves, so when the herring stay inside the net the sound is less threatening. During the cruise, Lindstrom’s crew lowered a hydrophone into the water so we could hear the whales at work.

Bubble-net feeding is a collaborative affair with humpback whales/NPS, Jim Pfeiffenberger

Interestingly, researchers believe that bubble-net feeding is a teachable behavior, “a kind of cultural transmission,” says Moran. Initially, this behavior was observed in southeast Alaska, but now researchers and whale-lovers are seeing this technique used more often in Prince William Sound and the Kenai Fjords area, he says. When we talked, he checked a site, Happywhale.com, which uses AI to identify whales quickly. He verified that southeastern humpbacks were there when I was. Recent collaborative research from the Alaska Whale Foundation and the Marine Mammal Research Program at the University of Hawai’i supports that these manufactured bubble-nets are complex tools.

We observe the same group perform their synchronous hunting several more times before heading to the Northwestern fjord and the Northwestern glacier. (Named after that university). Along the way, we delight in sleek Dall’s porpoises that look like baby killer whales speeding along the sides of our boat. We also spy puffins, otters, and pause to wonder at a noisy Stellar sea lion rookery in the Chiswell Islands. Like others, the Northwestern glacier is receding, and Lindstrom explains both the life cycle of a glacier and where this one once extended. Amidst small ice floes, we admire the light turquoise of its compressed ice and scan for calvings. This cruise is such a treat that I meet several locals who take it regularly during the summer months.

Lindstrom also points out the small, dark Kittlitz's Murrelet, which he refers to as “the polar bear of the bird world” that we’re unlikely to see elsewhere. “When you’re out in the Kenai, you aren’t seeing any human infrastructure,” Lindstrom tells me later. “You got a clear view of nothing but wild, and it's a real opportunity to come in and get in touch with that wilderness.”

On our way back, we encounter another temporary band of four humpbacks just making their living by bubble-net feeding. Our voices erupt in gratitude.

Amy Brecount White lives outside Washington, D.C., and loves to explore land, sea, sky, and river. Observing—and supporting—wildlife and their vital habitats along the way is always a goal and a bonus.