Fin Whale
FIN WHALE (Balaenoptera physalus)
The fin whale, also known as finback whale, is the world's second-largest cetacean. These baleen whales are found across all the world's oceans, feeding on tiny animals like krill and small fish. Interestingly, fin whales can successfully interbreed with blue whales and create viable offspring. Though classified as vulnerable, the fin whale population is estimated at over 100,000 adult individuals and is increasing in size.
Difficulty: Difficult
Fin Whale Description
The fin whale is the world's second largest whale, measuring around seventy-two feet (22m) in length, and weighing around forty-three tons. They are baleen whales, characterized by the baleen, rather than teeth, they use to sieve their prey from the water. Fin whales have dark brownish-gray coloration on their dorsal side, with two asymmetric chevron patches near the back of the head whales. They are lighter in color on their ventral side. Interestingly enough, they are not symmetrical as their left lower jaw is black, and their right side is white. Like all rorqual whales, the fin whale has grooves between the tip of the lower jaw and the navel, allowing them to expand their throat tremendously. Their two blow holes create a very tall and thin column shaped blow up to 18 feet (6m) high. During feeding bouts, fin whales will blow five to seven times in quick succession. When they are resting they will blow once every minute or two. The dorsal fin is sickle-shaped with a backswept shape. Fin whales are the fastest whales in the world, a behavior that is incredible to witness during our Gray Whales and Blue Whales of Baja photo tour.
This aerial view of a fin whale shows off its sleek, streamlined body. Fin whales are the second largest whale in the world, and one we hope to see on our Baja tour. Photo by Leonardo Gonzalez.
Fin Whale Distribution and Habitat
Fin whales are found in all of the world's major oceans, with the highest densities occurring in temperate and cool waters. There is a resident population of fin whales in the Gulf of California, with additional whales migrating to the area in the winter and spring time, right when we hold our tour in the Sea of Cortez. The migratory patterns of fin whales are poorly understood, but they definitely move with the seasons as they can be found in Alaska and Hawaii during different parts of the year. During the cooler seasons, fin whales in the Sea of Cortez are found closer to shore, mostly north of La Paz, with high densities around Loreto and just north of Santa Rosalía. As the temperatures warm, they move into deeper water. There are around 2,500 adult animals along the Pacific Coast of North America, some of which migrate into the Gulf of California. The resident population estimate for the fin whales in the Gulf of California is around 350 adult animals.
Our fin whale tour is held in early March, the time at which fin whales may be giving birth in the sea of Cortez, though this is still unconfirmed.
The coastal waters off of Loreto, in southern Baja, Mexico are the wintering feeding grounds for fin whales. We will look for the whales as they forage for krill in these waters. Photo by Andrea Izzotti.
Fin Whale Feeding Biology
As a baleen whale, fin whales filter feed mostly on krill, but also on squid, and small schooling fish. The exact dietary makeup of fin whales depends on the population's location. For our gray whale and blue whale tour in Baja, the fin whales we encounter mostly feed on euphausiids (Nyctiphanes simplex), a species of krill. The fin whales within the Gulf of California will migrate into deeper water, as the weather warms, following their prey.
To predate their food, generally found in bait balls, fin whales approach at around 6.5 mph, open their mouths and engulf up to 18,000 gallons of water with one gulp. It then closes its mouth, and pushes the water out, through its baleen, which gets trapped by the keratinaceous baleen. An adult fin whale has up to 473 baleen plates on each side of the mouth. Unlike many other baleen whales that surface feed, fin whales routinely dive to depths of more than 660 ft (200m) where it, on average, does four lunges to capture the krill prey. Within each of these gulps, a fin whale accumulates twenty two pounds of prey. Fin whales can eat as much as four thousand pounds of prey a day. To meet their energy requirements, fin whales need to forage for around three hours a day, unless prey densities are lower and more scattered. Feeding dive times in Baja average six minutes, and up to seventeen minutes.
Though fin whales do lunge feed at the surface for their prey, like this individual, they most often feed on krill below the surface. Photo by Kamonrat.
Fin Whale Social Organization
Fin whales are more social than other rorqual whales, often in groups of six to ten individuals. At times, they may even congregate into groups of a hundred animals, when they are gathering to feed. To communicate with each other, fin whales use very low frequency (16 to 40 hertz) down swept pulses, with 20 hertz calls being the most frequent. Fin whale songs generally last between 7-15 minutes, and can last for days with breaks in between the songs. Only male fin whales make these calls, indicating they are related to reproduction. Unlike other rorqual whales, fin whales rarely breach, spy hop, or fluke slap. Even when diving, fin whales often avoid raising their fluke out of the water.
Fin whales may be found as single individuals, but generally are found in groups of six to ten individuals. When feeding areas are good, up to 100 individuals may gather. Photo by Wildestanimal.
Fin Whale Reproduction
Fin whales only give birth and mate during the winter months. Gestation for fin whales takes between eleven and twelve months. The calf is around eighteen feet long, and weighs 4,000 to 6,000 pounds when born. Fin whale calves are weaned at about seven months, with females giving birth every two to three years. Males are sexually mature as early as six years and females seven years, though full adulthood isn't reached until about twenty-five years old. Fin whales are very long-lived whales with some individuals being estimated to be 140 years of age though ninety years is their longest confirmed age.
Fin whales give birth in the winter, during the time of our tour. We'd consider ourselves very lucky to find a mother and calf! Photo by Alberto Loyo.