How Whales Sing: The Science Behind Their Songs

Modern bioacoustic research uses hydrophone arrays deployed behind research ships to record underwater sounds. In Norwegian waters, researchers documented orca carousel hunting (driving herring into dense balls at surface) followed by sudden acoustic silence when sperm whales approached. Spectrograms revealed massive broadband noise from sperm whale mobs. Telemetry data showed sperm whales pursuing orcas over 20-50 kilometers, proving that sperm whales actively drive orcas from feeding grounds rather than simply defending territory.

Marine mammals use sound for communication, navigation, and finding food because light cannot penetrate deep water, making sound the primary communication medium in the ocean. Scientists use underwater microphones (hydrophones) and autonomous marine robots called gliders to record and analyze these sounds, creating spectrograms that reveal species-specific vocalizations. This bioacoustic research helps scientists locate whale populations, understand their behavior, and assess how human-generated noise pollution may disrupt marine mammal communication and survival.

Marine mammals rely on sound more than any other sense for navigation, communication, foraging, and reproduction. Cetaceans vocalize across the broadest frequency range of any animal—from infrasonic sounds (blue and fin whales) to ultrasonic frequencies (porpoises and beaked whales). Passive acoustic monitoring uses hydrophones deployed in the ocean to record whale sounds without emitting any sound, generating massive terabytes of data requiring sophisticated processing. Researchers use long-term spectrograms and automatic detection algorithms to analyze these datasets. Different whale populations produce distinct vocalizations serving as acoustic fingerprints—for example, Antarctic blue whales produce a characteristic 28 Hz moan call that shows geographic differentiation between ocean basins, while fin whales exhibit geographic variation in their call structure, particularly in interpulse intervals.

Researchers use hydrophones (underwater microphones) to detect and record whale sounds. Directional hydrophones use a dish to focus sound from specific directions, allowing researchers to locate whales by spinning the dish and observing changes in sound intensity. Omnidirectional hydrophones pick up sound from all directions. These can be attached to recording devices at the surface or placed in autonomous underwater housings for long-term recording. Researchers analyze recordings using spectrograms, which visualize sound by showing frequency, pitch, and energy level. Humpback whales produce three main types of calls: social calls (growls, moans, grunts, shrieks), feeding calls (high-pitched whaling sounds), and song calls (produced primarily in breeding grounds like Hawaii). Social calls serve various purposes including communication between mother and calf, group cohesion during feeding, and contact calls. In Sitka Sound, researchers must account for anthropogenic sound from tourism, vessel traffic, and fishing vessels. Humans and whales share oceans and sometimes compete for the same subsistence and commercial resources.

Bioacousticians use specialized tools to study animal communication. Directional microphones isolate specific sounds from noisy environments. Hydrophones capture underwater sounds for marine research. Spectrogram analysis transforms sound waves into visual graphs showing frequencies and amplitudes, revealing unique signatures for each species. Parrots have served as crime witnesses by mimicking human speech. These technologies allow scientists to decode the hidden languages of nature, from bird calls to whale songs.

Humpback whales produce complex hierarchical songs with repeating patterns organized into phrases, phrases into stanzas, and stanzas into complete songs lasting minutes to hours. Songs change annually within populations—new elements appear while old ones disappear. Changes spread horizontally through social learning, with one male introducing new elements that others adopt. Within months, entire populations sing the new version. Research published in Science showed new song themes appeared in Eastern Australian populations and later in Western Pacific populations, demonstrating cultural transmission across geographically separated populations.

Humpback whale song is conveyed culturally - whales learn songs from each other. They hear songs, pick up motifs, incorporate them into their own songs, and continue to develop and elaborate on these motifs. This cultural transmission allows whale songs to become increasingly complex over time as different whales add their own variations.

Male humpback whales sing complex songs with repeated patterns lasting 15 minutes or more. Every male in Hawaiian waters sings the same song, which gradually changes through time, demonstrating cultural transmission. Songs are so loud they reverberate through whales' entire bodies, allowing calves to feel as well as hear them. Some whales act as 'joiners,' listening and learning from singers. This cultural learning ensures knowledge transfer across generations and maintains species-wide communication traditions.

The Baobab network uses hydrophones 40 meters deep to triangulate whale sounds and identify speakers. Genetic sampling from shed skin (squames) reveals relationships. Songs vary annually and regionally, similar to human dialects, indicating cultural evolution. Whales influence each other's songs like musicians from different genres inspiring each other. This demonstrates that whale songs form an evolving 'sound culture' rather than being fixed, challenging the notion of static animal communication.

Humpback whales produce complex, organized songs lasting 6-30 minutes that are continuously modified by entire populations over time, with all whales in an area learning and updating their shared song weekly until it is completely replaced after several years; these songs, originally confined to underwater environments, have been recorded, studied, and even transmitted into space aboard Voyager spacecraft, representing one of the few examples of cultural transmission in non-human animals.

Multiple solutions exist to reduce underwater noise impacts: ship quieting technology (hull cleaning, propeller polishing reduces noise 3-6 dB); vessel slowdown programs achieving 1-3 dB reductions in key habitats; quiet sanctuary designation prohibiting vessel traffic; tiered port fee systems incentivizing quieter vessels; shipping lane modifications avoiding critical habitats; and consumer choices supporting local products. Electric boats offer promise but still produce some noise. Policy approaches require speed reduction mandates, quiet sanctuary designation, incentive programs, retrofit requirements for older vessels, and Transport Canada implementation. Some studies suggest 10% of the fleet produces 90% of noise, primarily older, poorly maintained vessels.

The Convention on Biological Diversity recognized in 2013 that the destruction of the ocean's acoustic habitat by naval engine noise, military sonar, and oil drilling represents a direct threat to the communicative capacity of these species, interfering with identity calls, hunting coordination, and communication between mother and calf. We are silencing conversations that began before human words existed.

Human activities, particularly shipping traffic, are causing unprecedented increases in underwater noise in the Arctic Ocean, disrupting marine mammals' essential reliance on sound for communication, navigation, and foraging; scientists are addressing this crisis through acoustic monitoring with hydrophones, partnerships with Indigenous communities, and policy initiatives like Canada's Ocean Noise Strategy, which aims to reduce noise through speed restrictions, protected areas, and quieter ship designs to preserve the Arctic's unique acoustic environment critical for species survival.

Acoustic habitat degradation is gaining momentum as an international concern, with the International Maritime Organization recognizing the ill effects of underwater radiated noise on marine mammals. Large-scale stranding incidents across the world and in India's western coast have increased manyfold, making shipping radiated noise a major conservation concern that requires innovative solutions.