Whale Trail: The Migration of Gray Whales
Each year, gray whales (Eschrichtius robustus) complete what is believed to be the longest migration of any mammal, traveling roughly 12,500 miles between the Arctic and Mexico. From the Bering Strait and the Chukchi Sea, they journey to the warm waters of Baja California’s lagoons to calve and breed before returning to their northern feeding grounds.
Witnessing this incredible wildlife spectacle is something to behold and it’s always a privilege to be in the presence of such immense creatures. In many cases, it’s not only gray whales that you will see but also blue and humpback whales, dolphins, and porpoises, as well as seals and sea lions.
Introducing the Gray Whale
As the sole living species in the genus Eschrichtius, the gray whale is a baleen whale and is named after the gray patches and white mottling on its skin. They can reach lengths of up to around 50 feet and weigh up to 90,000 pounds, with most adults living between 55 and 70 years of age.
Females have a gestation period of around 13 1/2 months and will give birth every one to three years. Most calves are born in the middle of January in shallow, lagoon waters, protected from predatory sharks and killer whales. When they are born, calves enter the world tail first and weigh around 1,500 pounds, with most around 15 feet in length.
In addition to the eastern Pacific population of gray whales (which numbers around 27,000), there is a smaller, western population that migrates between the Sea of Okhotsk and southern Korea. Despite conservation efforts, the population of the latter group has only grown slightly over the years, probably due to the slow reproduction rate of gray whales. That being said, in 2018, the population’s conservation status was downgraded by the IUCN from critically endangered to endangered, indicating some improvement.
Prior to the 18th century, there was also a North Atlantic population of gray whales, although they are believed to have been extirpated due to whaling. A moratorium on commercial hunting of the gray whale has seen the eastern Pacific population thrive and it is now listed as of Least Concern on the IUCN Red List of Threatened Species.
With their position at the top of the food chain, whales play an important role in the health of our marine environments and are carefully monitored by researchers. In addition, they sequester around 33 tons of CO2 during their lifetime, making them a pivotal player in the fight against climate change.
Following the gray whale on its annual migration
To better understand the lifecycle and behaviors of gray whales, we can follow them on their journey from the Arctic to Baja California. In the following section, we will outline their movements through the seasons and outline the best times to observe them in the wild.
Summer (June - September)
During the summer months, gray whales are in the Arctic, feeding in the nutrient-rich waters and building up their stores of fat in preparation for the migration south. Gray whales exhibit a unique feeding behavior that sees them turn on their side and use their baleen to sieve through sediment.
They prefer to feed on small amphipods and benthic crustaceans that reside in the seafloor sediment and it is for this reason that they largely inhabit coastal waters. Interestingly, most whales have a left or right-side preference for feeding and will have fewer barnacles on that side of the head.
Fall (October - December)
By late September/early October, gray whales leave their Arctic feeding grounds, with the drop in water temperatures and southward movement of the ice signaling their departure. It is pregnant females who lead the group on their journey south, with their destination being Baja California.
During the migration, gray whales travel around 75 miles each day at a speed of around 5 miles per hour. Entanglement in fishing nets and vessel strikes are among the dangers they face along the way, together with other sources of disturbance and ocean noise.
Winter (January - March)
By late December, the pod has arrived in Baja California and gray whales can be seen across the four lagoons of Guerrero Negro, Laguna Ojo de Liebre, Magdalena Bay, and Laguna San Ignacio. It is in these warm, sheltered waters that the pregnant females give birth.
Over the next few months, they will nurse their calves and ready them for the return journey north. Mothers and babies are known to be particularly friendly to whale watchers and actively seek out interactions.
Non-pregnant females and adult males use this time to mate, with their young born the following year. Gray whale numbers are at their most abundant between mid-February and late March.
In March, adult males and juvenile gray whales begin their migration north while the mothers and newborns stay a few weeks longer in Baja California. This gives the young an opportunity to grow a little bigger, ensuring they are strong enough to complete the northern migration. Even in late April/early May, you are likely to see a few mother-calve pairs in the lagoons.
When they do start heading north, the mothers and babies tend to stay as close to the coastline as possible while avoiding killer whales and great white sharks. Young gray whales will stay close to their mothers for the first nine months of their lives and nurse for around seven of those.
Up-close encounters with gray whales in Baja California
It goes without saying that Baja California offers some of the best whale watching in the world, with not only gray whales spotted here but also blue, humpback, Bryde’s minke, and pilot whales. A sea kayaking adventure is one of the most respectful and sustainable ways to view these giants of the sea up close, enabling you to slowly paddle in their presence.
Motorized boat tours are another popular option and are conducted with the animals’ welfare at the fore. In fact, some of the more inquisitive whales (known as “friendlies”) are known to approach the boats and seek out interaction with their human passengers.
No matter how you choose to observe gray whales in their natural habitat, it’s an astounding and humbling experience. Naturalist guides lead all of our whale encounter trips, with education a high priority. In addition to our sea kayaking expeditions in Magdalena Bay and San Ignacio Lagoon to see gray whales up close, we also offer trips through the Sea of Cortez to witness a variety of other whale species and orcas.