The episode of Nature on PBS, “The Fellowship of Whales”, presents some of the latest research about the behaviors of marine wildlife and humpback whales. As a baby whale travels with its mother from Hawaii to Alaska, observers see humpback whales breaching, listen to the humpback whale songs and witness the humpback whales' spectacular "bubble net feeding". But researchers are still working to discover the complete story about the humpback whale songs and feeding behaviors.
Humpback Whales Feed in Southeast Alaska
After the long whale migration from the warm waters of Hawaii, the humpback whales arrive in spring and summer at the Inside Passage of Southeast Alaska where the icy waters are rich with krill and herring. The whales are very hungry because most have not fed for months. The whales are swimming and breaching as they gather for the life-sustaining feast.
Captain Dennis Rogers of Alaska Sea Adventures is an expert on local marine wildlife on the waters in Southeast Alaska. He often leases his cruising vessel to humpback whale and marine wildlife research teams. Spring and summer is the perfect time to go on an Alaska cruise and observe humpback whales during bubble net feeding, and to take spectacular humpback whale photos and video footage.
Humpback Whales Follow the Whale Song of the Lead Hunter
In 1970, Judy Collins released her album, Whales and Nightingales. It may have been the first time the general public heard the hauntingly beautiful songs of the humpback whales. As more research has been gathered over the last 30 years, it is found that the humpback whale sings a different tune as he/she trumpets the call for the humpback whales to gather to feed.
When it is determined that the cruising vessel is over a school of herring and whales gather nearby, a hydrophone (an underwater microphone) is dropped into the water so researchers can hear and record the humpback whales’ songs and calls during the feeding. The whale leader's call intensifies, becomes gradually higher in pitch, gets louder and louder and faster and faster heading for a climax, until the whales burst up out of the water in unison filling their mouths with their catch of herring. After they groan and slide back into the water, the whales regroup to feed again.
According to marine wildlife research by the Alaska Whale Foundation, it is believed the humpback whale songs and calls during feeding may be used more toward controlling the prey than in coordinating whale movements. Though it was thought that only male humpback whales sing, researchers have discovered that some feeding calls are actually organized by dominant female humpback whales. In one case, a group of eight females formed a nucleus for one of the many feeding groups that was observed returning to Southeast Alaska for eight years.
Humpback Whales Create Bubble Nets to Trap Herring
Sonar is used to document bubble net structures including their depth, geometry, and relationship to prey. As the lead whale calls, the others tighten up the circles and start blowing air creating a net of bubbles forcing the herring to the surface. Then the whales gather together beneath the catch, surround, swim up and explode out of the water as their mouths fill up with their catch. If the hunt doesn’t work out, the lead whale calls it off and they start over.
Dr. Fred Sharpe, primary marine wildlife investigator from the Alaska Whale Foundation, remarks, "I remember my first bubble net. It was 1987 and my first time researching whales in Alaska. Sitting quietly on the waters of Chatham Strait, a circle of bubbles began to form at the surface. Over the hydrophone came a wild cacophony of trumpet blast. As the whales burst through the surface, I leapt up and cheered. That was the moment I became captivated with the Alaskan humpbacks."
No one knows exactly how and when this feeding behavior started. In the Nature program, “The Fellowship of Whales”, the baby whale is left behind and not included as her mother joins a group of humpback whales to feed. Though it is clear that the young whale learns the ways of the humpback whales from the mother, it may have to wait until it is older to be trained in bubble net feeding.