Orca
Orcinus orca

The orca is recognizable from a distance thanks to a contrasting color pattern and a dorsal fin without equivalent among other cetaceans. Here are the concrete criteria usable with binoculars or in photo-ID.

Color Pattern: Eye Patch and Saddle Patch

The body is shiny black on top, white on the belly and flanks. Behind each eye is an oval white eye patch, characteristic of the species. A gray saddle (or «saddle patch») is visible just behind the dorsal fin. The shape and pigmentation of this saddle vary by individual and constitute a reliable marker for individual identification in photo-ID, notably via the Happywhale platform.

Dorsal Fin: The Key Criterion

It is the first landmark to observe. In the adult male, it is straight, triangular, and can exceed 1.8 m in height. In the female and juvenile, it is shorter, between 0.9 and 1.2 m, slightly curved backward. Deformations (collapse, scars) allow long-term individual identification. In captivity, dorsal fin collapse is almost systematic; in the wild, it remains rare and often linked to pathology or stress.

Size and Sexual Dimorphism

Sexual dimorphism is marked. Males reach up to 9 m for 6 tons. Females generally measure between 5 and 7 m for 3 to 4 tons. This dimorphism is one of the most pronounced among cetaceans.

Low and Bushy Blow

The blow is short, bushy and bush-like, reaching 3 to 4 m in height. In calm weather, it is visible up to 3-4 km. It is less high and less columnar than that of large rorquals, which helps distinguish it from a distance.

Science now recognizes several ecotypes of orcas, some candidates for full species status according to recent genetic analyses (Morin et al., 2010, Genome Research). The ecotype determines the diet, group size, surface behavior, and vocal repertoire.

Resident Orcas: Fish Specialists

Resident orcas live in stable groups of 5 to 50 individuals, organized around the maternal lineage. They feed exclusively on fish, mainly chinook salmon on the Pacific coast. They vocalize abundantly and possess stable dialects unique to each pod, transmitted from generation to generation.

Transient Orcas (Bigg's): Mammal Hunters

First described by researcher Michael Bigg, transient orcas hunt marine mammals: seals, sea lions, porpoises, sometimes young whales. They travel in small groups of 2 to 6 individuals and vocalize little to avoid alerting their prey. They cohabit geographically with residents without ever mixing with them.

Offshore Orcas: The Least Known

Offshore orcas live far offshore, in groups that can exceed 60 individuals. Their diet is poorly documented, but studies suggest specialization on sharks, notably bull sharks and Pacific sleeper sharks. Their teeth show characteristic wear compatible with shark skin consumption.

Antarctic Ecotypes (Types A, B, C, D)

Four ecotypes have been described in Antarctica. Type A hunts humpback whales. Type B (known as «pack ice orca») specializes in Weddell seals and uses cooperative waves to dislodge them from ice floes. Type C, the smallest, feeds on fish under the ice. Type D, discovered in 2019 off the Kerguelen Islands, has a distinct morphology (very reduced eye patch) and remains little studied.

Northeast Atlantic Orcas

Two distinct groups are documented. The Iberian population numbers about fifty individuals, tracked by the GTOA (Grupo de Trabajo Orca Atlántica), and concentrates in the Strait of Gibraltar and off Portugal. A British Isles group, very small (fewer than 10 individuals), is tracked by the Hebridean Whale and Dolphin Trust; its reproduction appears to have stopped for several decades.

The society of resident orcas is one of the most complex documented among non-human animals. It is based on the maternal lineage and cultural transmission mechanisms comparable to those observed in primates.

The pod is the basic unit: a group of 5 to 25 individuals descended from the same female. The grandmother plays a central role, especially after her menopause. Studies on North Pacific resident populations show that the presence of a post-reproductive female significantly increases the survival of her grandchildren, particularly during lean salmon years (Brent et al., 2015, Current Biology). This phenomenon, rare among mammals, is interpreted as an evolutionary adaptation: the grandmother accumulates transmissible ecological knowledge.

Each pod has its own vocal dialects: distinctive call sequences, stable over decades, not found in neighboring pods. These dialects allow researchers to identify groups from a distance via hydrophone, without visual observation.

Hunting techniques are also transmitted by learning. Juveniles observe adults for months before participating actively. The carousel technique in Norway or intentional beach strandings in Patagonia are not universal instinctive behaviors: they are local traditions, specific to certain groups, which are lost if transmission is interrupted.

Orcas' hunting strategies are geographically variable and culturally transmitted. They illustrate the species' behavioral plasticity.

Carousel Feeding in Norway

In the fjords of northern Norway, resident orcas practice carousel feeding on schools of herring. Several individuals swim in a circle around the school, striking the water with their tail flukes to stun the fish, then swallowing them one by one. This technique requires precise coordination between pod members and is learned progressively.

Intentional Stranding in Patagonia

On the beaches of the Valdés Peninsula (Argentina), some orcas deliberately propel themselves onto the shore to capture sea lions. This technique, documented since the 1970s, is taught to young by adult females. It is specific to a small group of individuals and not found in other global populations.

Predation on Large Cetaceans

Type A orca groups in Antarctica and some transient groups attack humpback whales (Megaptera novaeangliae) and blue whales (Balaenoptera musculus). Documented tactics include separating a calf from its mother, exhaustion by relays, and drowning by holding underwater. These attacks can involve up to 20 individuals and last several hours.

Extraction of Great White Shark Liver

In South Africa, two males nicknamed Port and Starboard have been documented killing great white sharks (Carcharodon carcharias) to extract the lipid-rich liver with surgical precision. This behavior, observed since 2017, has caused a notable desertion of great white sharks in certain South African coastal areas (Engelbrecht et al., 2019, African Journal of Marine Science).

Reliable observation sites are linked to seasonal concentrations of prey or well-documented resident populations. Here are the main ones, with the ecotype concerned and the optimal season.

Norway (Tromsø and Skjervøy Fjords)

The fjords of northern Norway host resident orcas from October to January, following North Atlantic herring schools. Concentrations can include several dozen individuals. Local operators offer boat or kayak trips. The season is short but observations are among the densest in the world according to certified operator reports.

Iceland (Grundarfjörður, Snæfellsnes Peninsula)

Icelandic orcas also follow herring, with a season from October to March. Grundarfjörður harbor is a frequent starting point. Observations are less guaranteed than in Norway but remain regular some years, according to local operator data.

Strait of Gibraltar and Iberian Coast

The Iberian population of about fifty individuals is present mainly from May to August in the Strait of Gibraltar and off Portugal, during bluefin tuna migration. The GTOA has tracked individuals via photo-ID for decades. It is the most accessible population from metropolitan France.

British Columbia and Washington State

The southern resident (Southern Residents) and northern resident (Northern Residents) orcas of the North Pacific are among the best-studied worldwide. Observations are possible year-round from Vancouver Island or the San Juan Islands, with summer concentrations linked to chinook salmon. This population is listed as endangered by the Canadian government.

Valdés Peninsula (Argentina)

Intentional strandings on Punta Norte beaches are observable mainly from March to April, during sea lion births. Observations are sporadic and tide-dependent. The site is a UNESCO World Heritage site.

New Zealand and Crozet Islands

Observations at the Poor Knights Islands (New Zealand) and Crozet Islands (French Southern Territories) are less predictable. Local operators report regular passages but without strict documented seasonality. The Crozet Islands are known for orcas specialized in hunting king penguins.

Since 2020, orcas from the Iberian population have interacted with sailboats in the Strait of Gibraltar and off Portugal, sometimes causing rudder damage. This phenomenon has generated significant media coverage, often inaccurate.

Context: A Critically Endangered Population

The Iberian orca population numbers about 50 individuals and is classified as critically endangered by the IUCN. It relies almost exclusively on Atlantic bluefin tuna, a prey whose stocks have declined sharply. This demographic fragility makes each individual important for scientific monitoring.

Timeline of Incidents Since 2020

The GTOA records interactions since their start. Between 2020 and 2024, several hundred events have been documented, mainly involving young individuals. Damage primarily affects the rudder and skeg. Several boats have required towing. The number of incidents has increased annually, which the GTOA partly attributes to social learning within the group.

Behavioral Hypotheses

GTOA researchers do not interpret these interactions as aggression directed at humans. The most solid current hypothesis is that of a learned behavior, potentially initiated by an adult female nicknamed Blanca, then spread to juveniles by imitation. Some researchers also suggest a component of play or exploration. The trauma response hypothesis remains debated but not excluded (Lopez et al., 2022, Marine Mammal Science).

Recommendations for Sailors

The GTOA and Spanish and Portuguese maritime authorities recommend: avoid sudden maneuvers, shut off the engine if possible, do not try to repel the animals, and report the interaction via the GTOA's official form. These field data directly feed ongoing research.

The orca is protected in most territorial waters worldwide, but regulations vary greatly by country. The High Quality Whale Watching (HQWW) charter provides an international reference framework that I consider the minimum acceptable.

Recommended Minimum Distances

In British Columbia, regulations require a minimum distance of 200 m for southern resident orcas and prohibit positioning on their path. In Norway, no specific national regulations exist for orcas, but certified operators apply distances of 50 to 100 m. The HQWW charter recommends a lateral approach, engine idling, without intercepting the path.

Engine Noise Impacts

Resident orcas communicate with calls in a frequency range overlapping outboard motor and propeller noise. Studies on Southern Residents show that nautical traffic reduces foraging time and increases compensatory vocalization levels (Williams et al., 2009, PLoS ONE). Reducing speed and maintaining distance is not symbolic: it is a measure directly linked to individual survival.

Captivity: Data on Longevity and Pathologies

The Whale and Dolphin Conservation (WDC) has compiled data on captive orcas for decades. Average lifespan in captivity is significantly lower than in wild populations. Dorsal fin collapse, nearly universal in captivity, is associated with lack of exercise and confinement conditions. Stereotypic behaviors and dental pathologies from chewing metal structures are also documented. These data are public and accessible in WDC annual reports.

Contributing to Citizen Science

Any at-sea orca observation can be scientifically valuable. I use Happywhale to submit my dorsal fin photos: the platform automatically compares images to its global database and can identify the individual. In France, reports can be sent to Obs-MAM (OFB network) or Souffleurs d'Écume. A clear photo of the dorsal fin and gray saddle is enough for a useful contribution.