Orcas are cetaceans of the dolphin family, in fact they are the biggest “dolphins”. They are not whales (baleen cetaceans), son toothed cetes (toothed cetaceans) and, of course, they are not murderers.
They feed mainly on Atlantic bluefin tuna. This subpopulation NEVER come cetaceans or others sea mammals.
What is the Iberian orca?
The Iberian Orca is a different subpopulation, very small. They are called Orcas from the Strait of Gibraltar and the Gulf of Cádiz.
Their relatives would be individuals observed sporadically in the Canary Islands and they are genetically isolated from individuals who live in Norwegian and Icelandic waters.
The size of the adults of the Iberian Orcas is between 5-6.5 m. It is a small size compared to other orcas worldwide, such as the Antarctic ones that reach 9 meters.
The juvenile specimens measure from 3 to 4.5 m and the calves between 2 and 3 m.
In orcas there is a clear sexual dimorphism, namely, there are differences between adult males and adult females. Males present a much larger dorsal fin than females, exceeding 1.5 m of length. Calves present a cream coloration that will disappear becoming white”
Orcas in the Strait of Gibraltar are considered distinct from other Northeast Atlantic subpopulations, according to studies of photoidentification, mitochondrial DNA, microsatellite genetic markers, stable isotope ratios and contaminant loads (Esteban et al. 2016a). This small subpopulation, with a low number of mature individuals, relies heavily on an endangered prey species, Atlantic bluefin tuna (García-Tíscar 2009). Although the adult survival rates were estimated to be within levels known to be consistent with stable populations, poor long-term recruitment suggests a inferred decline in the future unless conditions improve (Esteban et al. 2016b).
For these reasons, this subpopulation of orcas was listed as vulnerable by the Spanish Ministry of the Environment in 2011 (RD 139/2011), which later published a conservation plan in 2017 (APM/427/2017), and they were classified as Critically Endangered by the IUCN Red List in 2019 (Esteban and Foote, 2019). As usual, in the Strait of Gibraltar orcas are observed actively pursuing tuna until exhaustion (Guinet et al. 2007) either preying on tuna caught by boats longline fishing (Esteban et al. 2016b).
Dispersion and migration
The Iberian orca subpopulation migrates from the Strait of Gibraltar to the north during the summer, since it is where the tuna move. In autumn they fan out from the north into deep water.
During the winter they return to the area of the Strait of Gibraltar, where they remain until the end of spring, repeating the cycle. The movements and migrations carried out by the killer whales are diffuse, that is to say, it is possible that not all the groups travel together but that they move progressively and will always depend on their prey, the Atlantic bluefin tuna.
Scarlet J-50. Photo credit: © Clint Rivers.
Scarlet J-50. Photo credit: © Clint Rivers.
J-56 Tofino with her mother J-31 Tsuchi
Picture credit: © Dave Ellifrit (2019)
The first moments in the life of an orca
After a gestation of 16/18 months, the Iberian killer whales give birth, the delivery will take place at any time, but more often between the end and the beginning of the year.
The expulsion does not take place on the surface of the water, the newborn is born tail first and the folded fins (dorsal, pectoral) stretch, as soon as expelled the newborn is brought back to the surface by its mother to take his first breath. But in case of complication other members of the group will be present to help and support the calf on the surface, it is for this reason that sometimes we can observe in nature, newborns with rake marks on the dorsal fin.
In December 2014, Scarlet J-50, a Southern Resident Killer Whale, was observed hours after birth with rake marks, leading researchers to believe she had been removed from his mother by other members of the group.
SIZES AND FEATURES:
His birth weight is around 180 kilos, and he measures between 2/2 meters 40 or (6/8 feet).
Fetal plaice will be present as well as whiskers on its rostrum which will be used to locate its mother's teats. These characteristics will persist for several weeks before disappearing.
The fins will lengthen, the dorsal fin will rise, become straight and firm.
The Beige/orange color will gradually disappear between 8 months and 1 year, giving way to the white and black color.
The newborn will swim alongside its mother and by touching it will stimulate its mother's teats. The mother will squirt the milk into the calf's mouth, but sometimes milk can get lost in the ocean.
The feedings, last only about ten seconds, but continue day and night. For a few days or even weeks after birth, the mother and the calf will not sleep.
The calf will start to eat solid food, around its first year, but will benefit from its basic diet (milk) until its 3 years.
In general the calf swims alongside its mother, but it will quickly understand that sometimes traveling behind its mother in the "slip Stream" this type of hydrodynamic wake, which its mother produces when swimming, to its advantage. An advantage that will allow him to spend much less energy and to be able to follow the pod.
In principle, scientists declare newborns in ID catalogs at the age of 1 year, because the mortality of calves under one year old is high.
If the calf is a year old, it is more likely to reach adulthood.
Most Iberian newborns are well over a year old, which is why we have included them in our ID catalog.
Over the months the calf will gain in weight and size, it will be more and more independent, with playful behavior. But will continue its cultural learning, for several years.
A FACT: often observed, when the mother is angry with her little one, she quickly lets it know by slapping her caudal fin on the water. The mother will immediately get the attention of her little one!
Iberian killer whale.
Photo credit: © CEMMA/GTOA (2015)
When the same species lives in different environments and has a different phenotypic expression, even if it is the same species, due to the reaction of genes with the environment, it is called an ecotype.
Scientists have identified 10 orcas ecotypes, but the true number is likely much higher.
We can find orcas in most seas and oceans around the globe.
But all these killer whales are not alike, and on many characteristics (culture, dialect, morphology, pigmentation, hunting technique, type of prey).
Some communities are nomadic, while others are sedentary. Living in the open sea, or on the coasts.
These different ecotypes may intersect geographically, but they do not normally mix socially, and will not breed with each other.
The Iberian orca is a subpopulation, it has a small morphology, a male measures between 5/6 meters. She has a blunt head, a black dorsal cape that doesn't show much contrast. between one layer and the other. It is a piscivore and its favorite prey is Atlantic bluefin tuna (Thunnus thynnus).
These killer whale exhibit two strategies for feeding on tuna: active hunting (until exhaustion) and longline depredation, which provides access to effortless catches and conserve energy for socializing.
During these interactions, killer whales scan the area around fishing boats, until they spot a tuna caught on a line, and catch the fish or part of it, before the fisherman can bring it to the surface. .
Deep lacerations and even amputations have been observed in these killer whales, which are thought to be linked to interactions with fishing (Herr et al., 2020; Otero-Sabio et al., 2018).
In 2011, 39 individuals were listed. In 2023, 35 Iberian individuals divided into (6 communities (A, B, C, D, E, F). And 14 individuals who have no community, but observed several times.
The Iberian orcas are a subpopulation belonging to the Atlantic orca population and are endangered.
The poster of the 10 orca ecotypes.
ational Oceanic and Atmospheric Agency (NOAA).
Illustrated by © Uko Gorter
Is it a protected species?
Cetaceans in general are protected in Spanish waters by the cetacean protection law, while in portuguese waters there is also a specific law for the protection of cetaceans. Any action contrary to those laws need un specific permission from the authorities.
The subpopulation is considered vulnerable. It is threatened and protected by different state regulations.
It was listed as vulnerable by the Spanish Ministry of the Environment in 2011 (RD 139/2011), which later published a conservation plan in 2017 (APM / 427/2017).
In Portugal there is not enough data for its categorization in the red book of mammals in mainland Portugal.
The IUCN red list considers it threatened and has classified it as Critically Endangered in 2019 (Esteban and Foote, 2019).