The Oregon Coast is home to an array of marine wildlife, some of whom live in the coastal waters year-round and some of whom are here for part of the year for a specific purpose.
One of the fascinating creatures who fall into the latter category are North Pacific humpback whales, one of conservation’s great success stories.
Humpback whales (Megaptera novaeangliae) are a species of baleen whale, or filter feeders. Rather than teeth, baleen whales have stiff keratin plates that grow down from the gums of the upper jaw and are used to strain small baitfish and zooplankton—such as krill—from the water.
Throughout the world’s oceans, there are 14 distinct populations of humpback whales, with each population defined by their winter breeding area. The North Pacific humpback whale is separated into four distinct population segments. Those who feed off the nutrient-rich waters of the Oregon Coast primarily migrate to the warmer waters of Mexico and Central America to mate and give birth.
“It is the North Pacific humpback whales’ seasonal residence in Oregon’s coastal waters that connects us, and our ecosystems, to other regions throughout the Pacific when they migrate south to reproduce,” says NCLC Marine Program Coordinator Rhianna Thurber, who has extensively studied the species.
The whales make this journey in search of warmer waters and less predation pressure on newborn calves. Although big at birth, humpback whale calves do not have enough blubber and fat to regulate their body temperature in the colder waters of Oregon. Being in the warm southern waters means the majority of calorie intake from their mother’s nutrient-rich milk goes toward helping a calf gain weight and put on body fat very quickly.
“This rapid weight gain allows the calf to prepare for a migration back to the northern feeding grounds with its mother at the end of winter,” Rhianna says.
Migration Patterns of Humpback Whales
When humpback whales migrate to the southern breeding grounds in the winter, they are fasting and relying on their stored body fat and thick blubber layer for survival, as there really isn’t anything for them to eat down there.
“That’s why feeding up here in the summers is incredibly important and a key aspect of successful reproduction” Rhianna says.
On average, they spend 90 percent of their waking time feeding. An individual humpback whale can consume approximately 1 to 3 tons of food per day, which is more than 3 million calories and equivalent to 5,300 McDonald’s Big Macs. They primarily forage on small baitfish, including anchovy, sardines, sand lance, and herring, as well as small zooplankton, such as krill.
While individual travel times vary, humpback whales typically begin their migration south in October. Depending on how fast they travel, it can take about four to eight weeks to arrive in the breeding grounds. They stay in the southern waters for another four to eight weeks before returning north, making for an approximate six-month roundtrip.
Compared to other foraging grounds in the North Pacific, such as Southeast Alaska, where whales can commonly be spotted from the shoreline, humpback whales are generally found feeding further offshore along the Oregon Coast, and they are most commonly spotted by commercial fishing vessels.
“The underwater landscape here off the Oregon Coast is different, where we have a relatively flat, moderately sloping continental shelf ,” Rhianna says, adding the whales are most notably found miles offshore.
In general, whales follow their prey, which means their foraging areas can shift because of changing ocean conditions, such as ocean acidification and hypoxia.
“Where the prey is, that is where they will be,” Rhianna says.
However, humpback whales have been sighted around the Oregon Marine Reserves, including Cape Falcon Marine Reserve. They’ve also been spotted in Mexico’s largest marine protected area, surrounding the Revillagigedo Islands.
The Process of Reproduction
While baleen whales do not form the same type of long-term familial associations as orcas, there is a cow-calf dependency period that typically lasts about one year. The calves are born in Mexico or Central America. Once they are big and strong enough for the journey, they migrate back to the Pacific Northwest with their mom in the summer. The following winter, when the calves are about a year old, they migrate south again with their mother, where they are eventually weaned. That amounts to a three-year commitment—from conception to weaning—for a successful reproduction cycle of a female humpback.
“It’s a huge energetic expense,” Rhianna says, adding that a mother can lose up to one-third of her total body mass after giving birth, nursing, and returning north to her summer feeding grounds.
However, it has been documented that whales will choose to forego the migration south. Given the energetic expense of rearing a calf, females generally do not reproduce every year, but often go two to five years between calves. If you see a whale spout during the winter, it’s likely a whale who has chosen not to reproduce.
“There is no sense in migrating 3,000 miles to play a dating game you want no part of when you can just stay up in the feeding ground and eat all winter long,” Rhianna says.
Male whales don’t contribute to parental care, but they do fulfill the role of an escort. You’ll often see a male humpback spending time with the cow and the calf while in the breeding grounds. Sometimes there are multiple escorts, vying for the female’s attention in hopes of being her next mate.
A Conservation Success Story
Another characteristic uniquely tied to the male humpbacks is the penchant for singing in the breeding grounds. When they sing, they do so upside down in the water column and the sound reverberates off the ocean floor. It is so loud that you could be diving in Mexico, Hawaii, South America or Central America and hear the sound below the surface—like an underwater symphony.
Each breeding population has their own song. For example, male humpback whales in Hawaii sing a different song from those breeding in Mexico. However, all the male whales in the population sing the exact same song, which varies slightly from year to year.
While there is no definitive conclusion as to why they sing, humpback whales are the only ones that demonstrate the behavior, and they sing regularly through the day and night.
When commercial whaling was still legal, Dr. Roger Payne, a bio-acoustician, recorded these vocalizations to produce the album “Songs of the Humpback Whale” in 1970.
This album reinforced that whales are highly intelligent beings and their songs are not only beautiful, but a meaningful form of communication as well. It helped spark the “Save the Whales” movement that challenged the commercial whaling industry. In 1986, the International Whaling Commission passed a global ban on industrial whaling.
At this point, the North Pacific humpback whale population was hunted to near extinction; about 90 percent of the population was depleted. Over the years, however, the North Pacific population has made exponential recovery.
“It is a really great conservation success story,” Rhianna says.
While populations are recovering, they haven’t yet returned to their pre-whaling abundance. Currently, under the 1973 Endangered Species Act, the Mexico population is listed as “threatened,” while the Central America population is listed as “endangered.”
Here are a few other cool facts about the North Pacific humpback whale:
- As the fifth-largest whale species, humpbacks average 40 to 50 feet in length and generally weigh about 1 ton (2,000 pounds) per foot, with females being larger than males.
- They can hold their breath for up to about 30 to 45 minutes, but the average dive time is about 7 to 15 minutes.
- We identify them using unique marking on the underside of their tail fluke (kind of like their own fingerprint), and their fluke is roughly 13 to 15 feet wide.
- Their throat is only about the size of a volleyball, so they really cannot swallow anything larger than small fish.
- The nodules on their face are called tubercles, which contain small sensory hairs, since one trait of being a mammal is having hair
Want to Get Involved in Community Science?
You can look up whale sightings and contribute your own through Happywhale, which engages community scientists “to identify individual marine mammals, for fun and for science.” Anyone can submit a photo of their sighting, along with the location, date and other information, and then Happywhale uses state-of-the-art image processing algorithms to match whale photos with scientific collections.
That means you can see if your whale has been sighted before, where the sighting occurred, and you can sign up to be notified if someone else spots the same whale in the future—wherever that might be.
“This groundbreaking database and technology has helped us link, identify and better understand the migratory patterns of these whale populations worldwide,” Rhianna says. “The best part is that anyone can do it!”
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