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Behaviour

Fin whales are very fast swimmers, reportedly reaching speeds of 20 to 25 knots in the open ocean, which led to their nickname ‘greyhound of the sea'. Fin whales dive to a maximum of about 470 m and may stay submerged for up to 15 minutes.

They rarely show their flukes when beginning a dive. Unlike blue or sei whales, fin whales do breach on occasion, leaping totally clear of the water and landing noisily on their side. This behaviour which might be a means of communication or advertisement to other whales. Fin whales are more gregarious than other baleen whales. While individuals are commonly observed, they are often found either in pairs (as in mother and calf) or in small groups up to six or seven individuals. Larger, loosely associated groups of 100 or more whales can be seen on the summer feeding grounds. In the North Atlantic, fin whales can be seen feeding in large dispersed group including other species like humpback whales, common minke whales and white-sided dolphins. There are also often found in association with birds.

TJacobsen Fin whale 3 MG 3315Group of fin whales. Photo: T. Jacobsen / PolarImage.dk

Feeding behaviour

Like most other rorquals, fin whales lunge-feed, “gulping” in large swarms of shoaling prey (see under diet for further details). Fin whales have these rorqual-typical accordion-like ventral chin groves that let them expand the mouth while filling it with water and prey.

They accelerate quickly (lunge), often from below, towards the surface, and turn or roll into a vast school of prey to engulf large amounts of food and water (gulping). Then they contract the chin folds, forcing the water out through the 260-480 fringed baleen plates hanging on each side of the upper jaw, leaving the prey trapped inside the mouth. On each of these bouts, or lunges, the whale engulfs about ten kilograms of krill contained within some 70,000 liters of water — a volume heavier than its own weight — in a few seconds. In less than a minute, all of the engulfed water is filtered out of the distended throat pouch as it slowly deflates (Zimmer 2007; Goldbogen 2010).

Fin whales have been observed circling schools of fish at high speed, rolling the fish into compact balls and then turning on their right side to engulf the fish. When a fin whale eats, it often turns on its side with the right side facing downward; in this position the lighter head colouration makes it less visible to prey.

Fin Whale feeding NOAA Fin whale feeding. Photo: NOAA  

TJacobsen Fin whale birds MG 3295 birdsFin whale and birds. Photo: T. Jacobsen / PolarImage.dk

Sounds and Communication

Recordings of regular, pulsed sounds, seemingly of mechanical origin, attracted considerable military interest in the 1950s, and eventually these sounds were conclusively linked to sightings of fin whales (Schevill et al. 1964).

Fin whales, like blue whales, communicate through vocalizations, using various moans, pulses, and grunts, that are mostly too low in frequency (infrasound, below 20Hz) for humans to hear them - unless they are modified, but are very loud. They can be as loud as 200 decibels (relative to 1 micropascal at one metre) and represent the most powerful and ubiquitous biological sounds in the ocean. They can be detected by other fin whales hundreds of km away.

Click here to listen to a fin whale call recorded in the Atlantic. Note that the sounds have been speeded up 10x, so they could be heard by human ears.

 

Most sounds are frequency-modulated down-swept infrasonic pulses from 16 to 40 hertz frequency. They also produce 20 Hz pulses (both single and patterned pulses), ranged low-frequency pulses and rumbles, and non-vocal sharp impulse sounds. Single frequencies (non-patterned pulses) last between 1 and 2 minutes while patterned calling can last for up to 15 minutes. The patterned pulses may be repeated for many days. Higher frequency sounds have been recorded and are believed to be used for communications between nearby fin whales and other pods. These high frequencies may communicate information about local food availability. (Bioacoustics Research Program 2010, Gambell 1985, McDonald et al.1995, Nieukirk et al. 2004, Watkins 1981).

Pulsed sounds include a "rumble" which is a call of very long duration (about 30 sec), in the frequency range of 10–30 Hz with extensive amplitude modulations. The association of these sounds with the reproductive season suggested that they might be used in reproductive displays by males (Watkins et al. 1987). By combining acoustic localization and molecular techniques, scientists showed later that only male fin whales produce these vocalizations which may function as male breeding displays (Croll et al. 2002).

Monitoring the acoustic activity of fin whales over long periods of time has shed new light on the poorly known habitat use of fin whales and their migratory patterns. Simon et al. (2010) have monitored the acoustic activity of fin whales over a 2-year period in the Davis Strait, between Greenland and Canada, using bottom-moored acoustic recorders. They showed that the whales migrate south much later than previously expected, likely mating at high latitudes (see under Migration for further details).

 

References