Fin whale (Balaenoptera physalus), illustration

Protected Balaenoptera physalus

Fin whale in Los Cabos

The fin whale is the second-largest animal on Earth, and the Gulf of California has its own population: a few hundred whales that live there year-round and have been genetically isolated for about 2,300 years.

23–26 mLength

36–73 tonnesWeight

Up to 45 km/hTop speed

~730Gulf of California population (2019 estimate)

When to see them

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

●● best months · ● regular · · occasional. Based on scientific studies and local reports; it changes year to year.

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How to recognize it

Very long, with a tall, slightly hooked dorsal fin set far back, about two-thirds of the way down the body. The giveaway is the head: the lower jaw is white or creamy yellow on the right side and dark on the left. Many have light-gray V-shaped chevrons behind the head. Its blow is tall and shaped like an inverted cone.

Biology

Fin whales live in oceans worldwide, but some groups never migrate, and the one in the Gulf of California is the best known. A 2002 genetic study found it to be a highly isolated, evolutionarily unique population of about 400 whales; a 2019 study estimated about 730. In winter and spring they feed close to shore in the Loreto–La Paz corridor, and in summer they move north to the Midriff Islands and the upper Gulf. Bahía de La Paz and the San José Channel are nursery areas.

They eat krill and small schooling fish, up to about 1.8 tonnes a day, lunging into a patch of prey with the mouth open and filtering the water out through 260 to 480 baleen plates. After 11 to 12 months of gestation, a calf is born about 5.5 m long. Fin whales can live around 90 years. Whaling killed nearly 725,000 in the Southern Hemisphere alone.

Things you probably didn't know

Isolated for 2,300 years

Gulf of California fin whales split from the North Pacific population about 2,300 years ago. A single mitochondrial DNA sequence accounts for about 92% of the whales sampled.

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They never leave

In 2001, 11 fin whales were tagged in the southwest Gulf. One was tracked for 13,199 km, but none headed toward the mouth of the Gulf, let alone left it.

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A song of their own

Fin whales sing with 20 Hz pulses. Gulf of California whales mostly sing triplets with shorter gaps between pulses, while southern California whales sing doublets.

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The greyhound of the sea

Fin whales are nicknamed the greyhounds of the sea because they can reach about 45 km/h.

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A mouthful bigger than itself

In one lunge a fin whale can take in about 70 cubic meters of water: more than the volume of its own body, about the size of a school bus.

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A whaling comeback

Thanks to the whaling bans, the global population roughly doubled since the 1970s to about 100,000 adults, and in 2018 the IUCN moved the species from Endangered to Vulnerable.

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Photos

Fin whale, photo 1 (Bahía de Loreto, Loreto) — iNaturalist contributor · iNaturalist · CC0

Fin whale, photo 2 (MX) — Reizo Knapp · iNaturalist · CC BY 4.0

Fin whale, photo 3 (Puerto Peñasco, MX-SO) — Miguel Grageda · iNaturalist · CC BY 4.0

Fin whale, photo 4 (United States) — Steven Lamonde · iNaturalist · CC BY 4.0

Fin whale, photo 5 — iNaturalist contributor · iNaturalist · CC0

Seeing them from the boat

Fin whales are not a regular sight off Cabo. The Gulf population spends the cool months in the Loreto–La Paz corridor and the summer farther north; tagged whales never moved toward the mouth of the Gulf, and sighting records give no sign that they travel out to the Pacific. Your best chance nearby is in winter and spring, from La Paz northward.

If you see a very tall, narrow blow and a long back with the dorsal fin far behind it, look for the white right jaw. Mexican rules give fin whales and blue whales more room than other whales: slow down, keep your distance and never chase.

Rules & conservation

Closest approach (NOM-131)	100 m for boats under 10 m, 120 m for larger boats; 240 m waiting distance for all other boats
Boats per whale or group	4 at most, for 30 minutes at most
Speed near whales	Under 5 knots, under 2 knots inside the watching zone
Not allowed	Fishing, swimming, diving, chasing, splitting up groups, getting between mother and calf
Mexico (NOM-059)	Subject to special protection (Pr)
Ley General de Vida Silvestre, art. 60 Bis	No marine mammal may be taken, except for authorized scientific research
IUCN Red List	Vulnerable (2018)

Don't confuse it with

The blue whale is mottled blue-gray, with a broad U-shaped head and a very small dorsal fin. Bryde’s whale is smaller (12–17 m) and has three ridges on top of the head instead of one. The sei whale is also smaller (12–18 m) and tends to sink below the surface instead of arching its back.

Questions

Can you see fin whales in Cabo San Lucas?

Rarely. The Gulf population lives farther north, from Bahía de La Paz up to the upper Gulf, and tagged whales never moved toward the mouth of the Gulf.

How do you tell a fin whale from a blue whale?

Look at the head: the fin whale’s lower jaw is white on the right side and dark on the left. The blue whale is mottled blue-gray and has a much smaller dorsal fin.

Are fin whales endangered?

The IUCN lists them as Vulnerable (2018) and the U.S. lists them as endangered throughout their range. In Mexico they’re subject to special protection, and the Gulf population is only a few hundred whales.