Fin whale guide: how big they are, their lifespan - and just how fast they can swim

What are fin whales?

The fin whale is a type of of baleen whale and the second-longest species of cetacean.

How big are fin whales?

These are truly impressive cetaceans. Surpassed only by blue whales in size, fin whales reach up to 24m in length and weigh up to 70 tonnes.

How fast are fin whales?

In shape they also resemble their blue cousins, with sleek hydrodynamic bodies, signifiers of their speed. So fast is the fin whale – able to reach 37kph – that it has been nicknamed the greyhound of the seas. It can outpace whale-watching boats which, in most oceans, remain its only pursuers.

Fin whale vocalisations

Along with that of the blue whale, a male fin whale’s vocalising is the lowest-frequency sound emitted by any animal. When observers from the US Navy first detected it, they thought that they were hearing Russian submarines. The sound can travel vast distances in water; a fin whale on one side of the Atlantic can be heard by a whale on the other side.

What do fin whales eat?

A fin whale' diet is usually made up of krill, small schooling fish, and squid. In total fin whales eat around 2 tons of food daily.

Cape Cod is also a good place to observe fin whales’ spectacular feeding technique. Turning on their sides like gigantic salmon, they lunge into a school of sandeels, flashing the white rorqual pleats on their bellies. Such encounters are a perfect way of seeing the whales’ unique asymmetrical markings, a clear diagnostic for the species. The left-hand side of the jaw is dark; the right, pearly white. Some scientists believe that the whales use the white side to startle and concentrate their prey.

How are different fin whales identified?

Unlike humpbacks, with their black-and-white flukes, individual fin whales are not easily differentiated. However, each animal has a distinctive pattern on its head, a greyish swoosh known as a chevron. Experts such as John Conlon, who works for the Dolphin Fleet whale-watching company out of Provincetown in Cape Cod, have therefore been able to assemble a fairly comprehensive photographic catalogue of fin whales. Differences in the dorsal fin, which ranges from curved backwards to standing straight, also help.

Where do fin whales live?

Fin whales are found in the deep water of all the oceans

Fin whale migration

Little is known about the calving areas of fin whales or their migration, though a new study concludes that their movements are quite different from other baleen whales such as blues and humpbacks. The scientists found that fin whales are more abundant in higher latitudes in warmer months of the year, and more numerous in lower latitudes during colder months, but some whales remain in higher latitudes in cold seasons, and vice versa. It appears that few fin whales frequent waters 20 degrees either side of the equator: some studies suggest that in the tropics Bryde’s whales fill the niche that fins might be expected to occupy.

How long do fin whales live for?

The longevity of these whales is a fascinating aspect of their natural history. Until recently we believed that they lived to about 70 years old. But in 2010 the results from the necropsy of a fin whale stranded on the coast of Denmark were released. Using amino acids in the whale’s eyes, they discovered that the animal, which observers had believed to be a juvenile, was 135–140 years old.

Threats

Sadly, fin whales, fast as they are, cannot escape one predator: us. The invention of steam engines and explosive harpoons brought them within the grasp of 20th-century hunters. Though the International Whaling Commission called a halt to their killing in 1986, fin whales are still hunted by the Japanese whaling fleets in the Southern Ocean. Iceland also resumed hunting fin whales in 2006; since then nearly 1,000 fins have been killed according to Whale and Dolphin Conservation (WDC). In 2014, 137 fins were hunted; their meat has been exported to Japan, where, WDC says, it has ended up in luxury dog food.

Icelandic whaling entrepreneur Kristjan Loftsson has even announced that he is introducing an environmentally sustainable way of hunting these animals – by using their own oil to power his whaling ships. The irony of such a gesture would not have escaped Herman Melville.