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Whale-come Back: Killer whale pod hunts returning salmon

A resident pod of killer whales has returned to Alaska's Glacier Bay National Park to feed on salmon. (NPS Video, S. Tevebaugh:Zenger).jpeg
A resident pod of killer whales has returned to Alaska's Glacier Bay National Park to feed on salmon. (NPS Video, S. Tevebaugh:Zenger)

Killer whales were filmed as they broke the water’s surface and gracefully arched back under in a picturesque Alaskan bay at the Glacier Bay National Park and Preserve earlier this month.

Park officials said salmon are beginning to travel back to their natal streams in Glacier Bay to spawn. Leaps of salmon were spotted in the fast-moving current of Sitakaday Narrows in mid-July.

On Thursday, the park explained in a statement that there are many distinct “ecotypes” of killer whales, or orcas, found in the park’s waters.

“In Glacier Bay, it is most common to see either ‘resident’ or ‘transient’ (also known as Bigg’s) killer whales. A third ecotype, known as ‘offshore’ killer whales, are primarily found off Glacier Bay National Park’s outer coast,” read the statement.

According to the Alaska Department of Fish and Game, the three ecotypes have been recognized by their genetics, morphology, acoustics, association patterns, and feeding ecology. Differences in their movement patterns have contributed to the names resident, transient and offshore.

In the video, members of the resident ‘AG pod’ are seen breaking the surface. The first whale in the video is a 27-year-old male named AG25.

“We know this from the shape of his dorsal fin and the gray area just behind the fin,” said the national park.

Killer whales’ dorsal fins may reach heights up to six feet in males and three feet in females.

Orcas have long lifespans and reproduce slowly, according to the Alaska Department of Fish and Game. Experts estimate males can live up to 50 years and females up to 80 years. Though the whales have multiple breeding partners throughout their lifetimes, young are typically born at intervals of three to eight years.

The park explained the name “resident” is a misnomer, since the whales travel widely throughout the year.

When ice retreats in the spring, the whales tend to migrate north throughout the Bering Strait. In the fall when the ice advances, they travel away from the northern Beaufort and Chukchi seas.

Still, resident killer whales tend to return each year to predictable locations, while transient and offshore whales have less predictable movement patterns.

“The AG pod is most commonly sighted in southeastern Alaska but has also been documented in Prince William Sound and Kachemak Bay,” the park said.

Orcas are top predators in Alaskan ecosystems. Though each pod has different hunting tactics, resident whales feed exclusively on fish, mainly salmon, while transient whales eat squid and marine mammals, according to the National Oceanic and Atmospheric Administration.

(Edited by Ali McCadden and Kristen Butler)

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