Humpback Whales: Migrating Giants

Humpback whales (Megaptera novaeangliae) are fascinating marine mammals; they are among the largest whale species on the planet. They are found in almost every ocean and might also be the nicest animals in the world. They also happen to have one of the longest migrations of any mammal. In this post, we’ll learn more about these magnificent whales and take a closer look at the incredible journeys they make every year between their cold-water feeding grounds and their warm-water breeding grounds.

Humpbacks are identifiable by their long, scalloped flippers, which are about a third of their body length. Their Latin name literally means “big winged of New England.” However, they get their common name thanks to the unmistakable “hump” on their backs near their dorsal fin.

Humpback whales are members of the rorqual family. This family also includes the Blue whale, Fin whale, Sei whale, Bryde’s whale, and Minke whale. Rorquals are identifiable by the presence of ventral grooves extending from the lower jaw down the throat to the belly. These grooves allow the mouth cavity to expand extremely wide to gulp large amounts of food.

At full maturity, the humpback whale ranges from 40 – 60 ft. (12-18m) long and can weigh up to 80,000 lbs! These whales reach sexual maturity between the ages of 4 and 10. Females give birth to a single calf, on average, every 2 to 3 years. Newborn calves range between 9 – 14ft. (3 – 4.5m) long and weigh up to a ton (2,000lbs).

The Epic Migration

There are 14 distinct populations of Humpbacks, each dependent on their warm-water breeding grounds. Humpback whales can travel with extreme precision over large expanses of open ocean in any weather condition. Depending on where the population lives, individual migrations to polar feeding grounds can range from 4,000 up to 7,000 miles (6,400 – 11,300 km) each way! The longest journey is from Antarctic waters across the equator to coastal breeding sites in Panama.

Map showing locations of the 14 distinct population segments of humpback whale worldwide – Credit: NOAA

Feeding Season

The season starts in summer when whales migrate to the poles to feed. Unlike other baleen whales that only eat krill, humpback whales eat a varied diet of krill, small fish, and crustaceans. Humpback whales highlight their intelligence by utilizing bubble nets to trap their prey. Pods gather groups of fish or krill by circling them while periodically blowing from their blowholes. This creates walls of bubbles that contain prey while multiple whales feed. Other methods of catching food involve slapping their tails against the water to create loud sounds to scare and immobilize prey.

Humpback whales can consume up to 2,000 pounds of food per day! Whales must eat enough in the summer to build essential blubber stores for the long migration and mating season ahead. This is especially true for pregnant mothers.

Mating Season

As winter comes, humpback whales migrate to warmer tropical waters around the equator to socialize and reproduce. Rorquals have a year-long gestation, so mating and birthing take place around the same time of year. Despite being a larger species of whale, humpbacks are incredibly acrobatic. Males compete against other males for mates with jumps and elaborate vocalizations.

Once these whales finish mating and giving birth, they begin the journey back to their feeding grounds to bulk up on food and prepare for the next mating season.

Threats to humpback whales

A major threat to these whales is injury or death by boat strikes during migration. Humpback whales are vulnerable to strikes throughout their range, but the risk is much higher in coastal areas with heavier ship traffic. To keep calves safe from predators, humpback whales will travel in pods and keep close to shore. Unfortunately, this brings them closer to boat lanes and fishing gear.

Another threat is starvation. Humpback whale migrations are typically timed with seasonal weather patterns like algae blooms, so changing weather and climate patterns can lead to a delayed or early arrival of pods. Specifically, if ice around the poles melts early, there may be less food available when they arrive. This leads to the potential for increased competition between species that may not have existed before.

We wrote an entire post about the threats to baleen whales. These same threats also impact humpback whales. You can check it out here!

Each population has distinct threats and needs. The good news is, populations have begun to bounce back after the ban on commercial whaling. The International Union for Conservation of Nature (IUCN) changed the status of the humpback whale from endangered to vulnerable. Despite these changes, we should still support these beautiful whales and encourage their protection.

Thanks for reading!

Did you like this post on humpback whales? Check out our post on how researchers found the lowest concentrations of contaminants in Antarctic humpback whales here:

What can whales tell us about pollution in Antarctica?
Briana Maloney

Brianna has a background in marine biology and currently works as a live-aboard deckhand/educator at the Los Angeles Maritime Institute (LAMI). Her research interests include ocean conservation, specifically in the high seas and polar regions, and identifying marine mammal vocalizations in the global soundscape. She is passionate about music and can’t write without coffee.

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