Exploring Whale Migration: A Global Journey

Whales are known for their impressive migration patterns, with some species travelling vast distances. Humpback whales, for example, are known to migrate between warm-water breeding grounds in the winter and cold-water feeding grounds in the summer. They are found in oceans all over the world, and one particular humpback whale named Frodo swam nearly 7,000 miles from the Mariana Islands to Mexico between 2017 and 2018, setting a new distance record for his species.

Why do whales migrate?

Whale migration is a fascinating phenomenon that has long intrigued both the general public and the research community. While not all whales migrate, those that do embark on some of the longest migrations among animals, often swimming thousands of miles over several months. The reasons behind whale migration can vary depending on the species, but there are several key factors that drive these majestic creatures to undertake such arduous journeys.

One of the primary reasons for whale migration is the availability of food. During the warmer months, food sources in certain regions may become scarce, prompting whales to migrate to colder waters where food is more abundant. This is particularly true for species like humpback whales, which are known for undertaking incredibly long migrations of up to 15,000 miles. By migrating to colder, food-rich waters, humpbacks can ensure they have enough nourishment to sustain themselves throughout the year.

In addition to feeding, mating and reproductive strategies also play a crucial role in whale migration patterns. As the colder waters begin to drop in temperature and food sources deplete, whales migrate towards warmer waters, typically near the equator, where they can mate and give birth in a safer and more favourable environment. This is especially important for the survival of newborn calves, which have a thinner layer of blubber compared to adults, making it challenging for them to regulate their body temperature in frigid waters.

Another factor that has been recently proposed to explain whale migration is moulting or skin shedding. Whales, like all mammals, regularly shed their skin cells. Scientists have suggested that whales foraging in freezing waters may conserve body heat by reducing blood flow to their skin, which interrupts the normal skin sloughing process. By migrating to warmer waters, whales can revive their skin metabolism, facilitating the moulting process. This theory is supported by observations of whales in frigid Antarctic waters, which often display a yellow discoloration due to the accumulation of diatoms, indicating impaired skin moulting.

It is worth noting that not all whales follow predictable migration patterns. Some species, like killer whales, tend to migrate wherever their food source goes. Male sperm whales, for instance, are known to be wanderers, travelling the world's oceans during their lifespan without following a particular route or pattern. Additionally, some individual whales, typically non-breeding members like juveniles, may opt out of annual migrations.

In conclusion, whale migration is a complex and varied behaviour influenced by a combination of factors, including feeding habits, mating patterns, and physiological needs such as moulting. By understanding these factors, we can gain valuable insights into the lives of these fascinating creatures and work towards their conservation and protection.

Where do whales migrate?

Whale migration patterns are complex and vary by species. Some species, like the Omura's whale, are not known to migrate at all. For those that do, the two main reasons are feeding and mating.

During the warmer months, food sources in warmer waters can become scarce, causing whales to migrate to colder waters where food is more plentiful. When the colder waters become too cold and food sources are depleted, whales migrate back to warmer waters.

Humpback whales, for example, are known for undertaking some of the longest migrations on Earth. They migrate between the tropics and polar waters, travelling along the coasts of 28 countries in the Southern Hemisphere and the open ocean. One humpback whale was tracked travelling 18,942 kilometres over 265 days, from its summer foraging area near the Antarctic Peninsula to its winter breeding area off Colombia, and back to the Antarctic Peninsula.

Another humpback whale, named Frodo, completed the longest-known movement for his species, swimming nearly 7,000 miles from the Mariana Islands to Mexico between 2017 and 2018. Frodo's journey also included appearances near Russia's Commander Islands in 2010 and 2013, indicating that some humpbacks circumnavigate the entire North Pacific.

In addition to humpback whales, several other species are known to migrate, including blue, sperm, gray, right, and orca whales.

How far do whales travel?

Whale migration patterns are complex, and some whales travel further than others. Humpback whales are known to make some of the longest migrations of any whale species. They migrate seasonally between the tropics and polar waters, travelling through the coastal waters of 28 countries in the Southern Hemisphere. One humpback whale was tracked travelling 18,942 kilometres over 265 days, from the Antarctic Peninsula to Colombia and back again. Another humpback whale, named Frodo, swam nearly 7,000 miles from the Mariana Islands to Mexico between 2017 and 2018, setting a new record for the longest movement of his species.

Humpback whales are not the only species to migrate over long distances. Blue, sperm, gray, right, and orca whales are also known to migrate. In fact, nearly all whales migrate, except for a few species like Omura's whale. Whale migrations can be as long as 15,000 miles and can take months to complete.

The main reasons for whale migrations are feeding and mating. During the warmer months, food sources can become scarce, so whales migrate to colder waters where food is more plentiful. When the colder waters become too cold and food sources are depleted, the whales migrate back to the warmer waters where they can find mates.

Whale migrations are essential for the health of the ocean and the planet. Whales fertilise marine ecosystems and support marine life as they move through it. Their faecal plumes boost phytoplankton production, which captures carbon dioxide and generates oxygen. When whales die, they sink to the seabed, taking massive amounts of carbon out of the atmosphere for centuries.

What are the dangers of whale migration?

Whale migration is essential to the health of the ocean and the planet. Whales fertilise marine ecosystems and support marine life, boosting phytoplankton production and capturing carbon dioxide. However, whale migration is becoming increasingly dangerous due to human activity.

One of the primary dangers of whale migration is entanglement in fishing gear. Each year, approximately 300,000 cetaceans, including whales, dolphins, and porpoises, become entangled and die. Right whales are particularly vulnerable, with around 86% of them expected to become entangled in fishing gear at least once in their lifetime.

Another threat is the ever-increasing shipping traffic, which leads to more collisions between whales and ships. These collisions can be fatal for the whales, and shipping lanes often overlap with whale feeding grounds, as seen in the case of blue whales near Sri Lanka.

Underwater noise pollution, caused by shipping traffic, is another issue. It has been increasing by more than double each decade and poses a significant risk to whales, as they rely on sound to navigate and communicate.

Climate change is also impacting whale migration. The shift in prey populations, especially in polar regions, makes it harder for whales to find food. Additionally, plastic pollution, including microplastics, poses a threat to whales, as they may ingest it, mistaking it for food.

The combination of these dangers poses a severe threat to whale populations, with six out of the 13 great whale species now classified as Endangered or Vulnerable. Protecting whales along their entire migration routes, or "blue corridors," is crucial for their survival and the health of our planet.

How do whales benefit the planet?

Whales play a vital role in tackling climate change and maintaining a healthy ocean. They are among the largest creatures on Earth and their bodies act as enormous stores of carbon. When whales die, they sink to the ocean floor, taking all the carbon stored in their bodies to the deep sea, where it remains for centuries. This process of carbon sequestration helps to remove climate-harming carbon from the atmosphere.

Whales also contribute to carbon sequestration throughout their lives. They feed in the deep ocean and then return to the surface to breathe and defecate. Whale faeces is rich in iron, which creates the perfect growing conditions for phytoplankton. Phytoplankton may be microscopic, but they have an enormous influence on the planet's atmosphere, capturing an estimated 40% of all CO2 produced. This is four times the amount captured by the Amazon rainforest.

Whale populations also have an impact on marine ecosystems. For example, as whale populations declined, orcas began preying on smaller marine mammals like sea otters. This led to a decline in the otter population, which in turn caused the spread of sea urchins that munched away at the kelp forests around the North Atlantic, further impacting marine carbon sequestration.

Restoring whale populations to their pre-whaling numbers could be an important tool in tackling climate change. Whales are not only effective at capturing carbon but they also have plenty of space in the ocean to do so. In addition, whale carcasses provide a unique habitat for deep-sea species, many of which are only found on these 'whale falls'.

Whale protection must become a top priority in the global effort to combat climate change. Their survival should be integrated into the objectives of the Paris Agreement for combating climate risk.

Frequently asked questions