My Research Project - Background

Each year, humpback whales migrate between their feeding areas in high-latitude places such as Alaska, California and Antarctica to their breeding areas in more tropical regions such as Mexico, Hawaii, Central America, and the South Pacific. This means that during the winter, all of the animals should be in the breeding area and none should be in the feeding area. It turns out that this isn’t true. All around the world, people have observed humpback whales in feeding areas during the winter when they are expected to be in the breeding area. This leads to the following questions: Who are these animals that spend their winters in the feeding area? Are they mostly males? Females? Juvenile animals? Why would they give up their chance to reproduce for the year?

It was these questions that led me to choose my project. For my master’s thesis at Moss Landing Marine Laboratories in Moss Landing, California, I will attempt to answer at least some of these questions. To do this, I will look at the animals off the coast of central California, an important feeding area for humpback whales that breed off the coast of Central America (see map for details). I will be looking at the sex-ratio (the number of males present compared to the number of females present) and the proportion of juvenile animals (the number of young animals compared to the number of adult animals) in this area throughout the year. By seeing how the sex-ratio and the proportion of juvenile animals change from summer to winter, I will be able to determine who is using the area in the winter. For example, if the sex-ratio is 1:1 in the summer (1 male present for every 1 female present) and 1:2 in the winter (1 male present for every 2 females present), I will know that there are more females than males using this area in the winter.

The different sexes and age groups of humpback whales are known to migrate to the breeding area at different times. Adult males are the first to begin the migration to the breeding area, followed by non-pregnant females, juvenile animals and finally pregnant females. This pattern would suggest that female animals in the late-stages of pregnancy remain in the feeding area longer than most other whales. This theory is supported by observations from the feeding area and during migration, but it has never been confirmed that pregnant females remain in the feeding area longer than most other members of the population. I will test this theory by determining the pregnancy rates of females found in the feeding area in the late fall and early winter. If a greater proportion of these females are pregnant than would be expected, this theory would be confirmed. The identification of this area as critical habitat for these pregnant whales would have profound implications for their conservation and management.

Information About Humpback Whales

Where do humpback whales live?

Humpback whales are found in every major ocean on the planet. These animals spend the summer feeding in high-latitude areas like Alaska and Antarctica, where the highly productive oceans give them a lot of food to eat. In the winter, they migrate to low-latitude areas such as Hawaii and Central America to breed. The largest populations of these whales feed in the waters around Antarctica and breed off of the coasts of Australia, New Zealand and many of the smaller islands in the south Pacific.



How big are they?

Adult humpback whales grow to be 40 to 55 feet long, which is longer than a school bus. They reach weights of around 79,000 pounds or about 40 tons! The females usually grow larger than the males. Young humpback whales are called calves. Newborn calves are usually around 14 feet long and weigh 2.5 tons.

What do they eat?

Small fish and shrimp-like animals called krill make up most of a humpback whale’s diet. These whales are baleen whales, which means they feed in a very special way. Instead of teeth, these whales have long rows of comb-like plates called baleen that hang down from the roof of their mouths. These bristly structures are made out of keratin, the same material which makes up hair and fingernails. When humpback whales eat, they gulp in a huge mouthful of water with fish or krill in it, then they use their massive tongue to force the water out through their baleen. The baleen lets the water escape and filters out the food, which is then swallowed by the whale.




How often do they have calves and how many calves do they have at a time?

Female humpback whales are capable of having calves every year, though they often take a year or two in between calves to rest. The pregnancy lasts around 11.5 months, which means they get pregnant in a breeding ground one winter and give birth on the same breeding ground the next year. Though twins have been seen in humpback whales, this is very rare and one or both calves usually die.

Where do humpback whales get their name?

Most whales and dolphins have a large fin on their back, called a dorsal fin. This is the large, visible fin seen in dolphins and killer whales. Humpback whales have a small dorsal fin which sits on a large bump (or hump) about two thirds of the way back on their body. This is the origin of their common name. Their scientific name is Megaptera novaeangliae. In latin Mega means big, ptera means wing, novae means new, and angliae means England. So the whole name means “Big-Wing New England.” This may sound a bit funny, but humpback whales have very long pectoral fins (the fins that are where our arms are) which almost look like wings, and they were first seen in very large numbers off the coast of New England. This is how they came to be called Megaptera novaeangliae or Big-Wing New England.

Does anything eat humpback whales?

Apart from humans, humpback whales have very few predators. Killer whales sometimes kill and eat humpback calves. They have been known to kill adults, but whether or not this occurs frequently is the source of much debate. Large sharks such as tiger sharks and white sharks are also known to attack calves. Sharks have never been documented to have killed an adult humpback whale.

Do whales sleep?

Strangely enough, whales don’t actually sleep like we do. For whales, breathing is a conscious behavior, not a reflex like it is in humans. When we are knocked unconscious, our body keeps breathing. If this were to happen in whales, they would drown. Instead, whales consciously control each breath. This means they cannot go fully unconscious like we do when we would sleep, or they would stop breathing and suffocate. Instead, these animals “sleep” with one half of their brain at a time. One half will rest, while the other half stays awake. Then they switch halves. When they are doing this, they sometimes float in one spot or travel very slowly.

References and Links

Wikipedia: Humpback Whale

Enchanted Learning: Humpback Whale

National Geographic

New World Encyclopedia

Ask Nature