The fin whale is one of the largest animal species in the world, second only to the blue whale. During our 12-day Searcher Natural History Tours to Baja, we can see fin whales at any point during the trip (except for the two days when we visit San Ignacio Lagoon to observe gray whales up close). Fin whales on the Pacific side of the peninsula seem to be part of the greater eastern North Pacific population, whereas those in the Gulf of California/Sea of Cortez are apparently a resident population with limited interaction (i.e., low gene flow) with fin whales elsewhere.

Fin whales are among the fastest of the large whales, with burst speeds up to 23 miles per hour (37 km/hr). For this reason, they were able to evade many of the Yankee whalers during the early years of commercial whaling. Unfortunately, modern whaling fleets wreaked havoc on all whale populations, including fin whales. Much is not known about current population trends, but for some populations of fin whales it seems their stock status is improving.

For the most part, fin whales do not usually exhibit the dramatic out-of-water behaviors that we see with humpback whales. Fin whales tend not to breach, fluke, flipper-flap, or lob-tail. In all my years of whale watching, I’ve seen the flukes of a fin whale on only two occasions, once off Long Island, NY and once off the California coast. Between their fast speed, their lack of demonstrative behaviors, and their relative elusiveness (compared to a humpback), it can be difficult to get a good look at a fin whale. Nevertheless, there are some useful traits we can use to help identify them.

Size and shape of spout/blow: The fin whale’s blow is usually tall and columnar, similar to but not quite as tall as that of a blue whale. From a distance, it would be difficult to distinguish the blows of a fin whale and blue whale. Even large humpbacks are capable of producing blows that might be construed as being from either a blue or fin whale. The blow alerts us to the presence of the whale, and we then use other clues to confirm the identification.

Size of animal: Fin whale adults are normally well over 50 feet in length, making them longer than most of the other baleen whales we see (humpback, Bryde’s, gray, and minke). When a whale surfaces for air, only a small portion of the animal is visible, so it takes some practice to develop a sense of the size of an animal based on this partial view.

Color: The overall color of the fin whale is slate gray, but the appearance of the animal will depend on lighting and individual variation. Some animals appear more brown than gray. The fin whale has several color features that are diagnostic, but are sometimes difficult to see. The color of the right lower jaw is white, unlike the gray color of the left jaw or the rest of the head. Asymmetry is uncommon in animals. Another asymmetrical color feature is a swirly color pattern (sometimes called the “blaze”) on the right side of the head. Finally, there is a V-shaped light-gray or white mark on the back called the “chevron.” Please note that these color features are not always obvious. I’ve seen many fin whales, but rarely have I had a good look at the white lower jaw. Many times I’ve been on the left side of the animal and could not see the blaze or the right lower jaw. More times than not the lighting was such that I could not clearly make out the blaze or chevron.

Dorsal fin: The dorsal fin of the fin whale has the classic curved “falcate” shape that we usually associate with whales and dolphins. This shape is in contrast to the lack of a dorsal fin in the gray whale and the hump-like dorsal fin of the humpback whale. The fin whale’s dorsal fin is prominent and appropriately sized for the body, in contrast to the smaller-than-it-should-be dorsal fin of the blue whale. Both Bryde’s and minke whales have prominent dorsal fins similar to that of the fin whale. The fin whale’s dorsal is more swept back than the slightly more-upright dorsal of the Bryde’s whale. The fin whale and minke whale can easily be separated by body size, so don’t let the dorsal fin fool you. As always, account for individual variations in size and shape of the dorsal fin within a species.

Tail flukes: Fin whales almost never show their tail flukes. The flukes are similar in shape to that of the blue whale (i.e., wide and tapered). The color is grayish-white, with perhaps a darker edging on the underside.

Species-specific traits: The unique traits of the fin whale are the asymmetrical color features: the white lower right jaw and the blaze color swirl on the right side of the head.

Behavior: When we see fin whales in Baja, most of the time they are simply swimming and diving. If they are traveling, the Searcher can sometimes match their speed and heading and we can anticipate where they will re-surface. If the whales are feeding underwater, their movements are more erratic and it becomes more difficult to predict their re-appearance.