Surprise with orcas in São Miguel

Last Saturday, January 8th, we were lucky enough to find a group of orcas off the coast of São Miguel island, about 6 miles from Ponta Delgada. A group of 4 individuals was on the move – one male, two females and a juvenile.

We had the opportunity to photograph and record them, with the objective of trying to identify if this group is already registered in the Futurismo orca catalog or even in some North Atlantic orca catalog, or if, on the other hand, it is a new group to study and analyze scientifically.

The individual with the highest and straightest dorsal fin that we see in the photographs is the male and the female has the lowest and most curved dorsal fin. We do not know exactly where they came from or where they are going, but we do know that this is the most widely distributed mammal on planet earth – they are found in all oceans, from polar to tropical waters.

In the Azores, orcas are usually seen in small family groups with at least one male. Although, they have a complex social structure, scientific studies indicate these species as matriarchal (the females lead).
In fact, it is not very common to see orcas in January in the Azores, but interestingly, precisely 9 years ago, on January 8, 2013, a group of orcas was seen in São Miguel. One of these was named Mr Ray because at the time he was interacting with a ray. We also know that between May 2006 and December 2015, Futurismo biologists recorded 24 sightings of orcas. The data collected are the result of research by Futurismo’s marine biologists that you can see in the poster below.

This is an occasional species in the Azores, normally found in the months of March and April (curiously the time of year when tunas usually start to appear in the Azores). We have records of orca sightings in 2019 (March); in 2021 (April and May).
Photo identification makes it possible to identify individuals using natural marks captured in photographs. For this species, the dorsal fin and/or saddle patch (mark posterior to the dorsal fin) is mainly used.
At the moment in our catalog, we have a record of 54 individuals.

As for the study carried out by Futurismo in this area of ​​research, we currently have the marine biologist Georgina Cabayol, responsible for updating the catalog and who is currently doing her master’s thesis on orcas in the North Atlantic.

Contrary to what one might think, this is the largest dolphin species and not a whale. It belongs to the suborder Odontoceti and the family Delphinidae. The name “killer whale” is believed to have been given anciently by sailors who witnessed these animals attacking whales and the name naturally evolved from “whale killer” to killer whale.

Orcas can eat a little bit of everything – fish, sharks, cephalopods, marine mammals, turtles, seabirds. In our waters, this predator prefers tuna.

As for the size of the orcas, it is the largest of the dolphins, it can reach a maximum size of 9.8m in males and 8.5m in females. As for weight, males can reach about 10,000 kg and females 6,000 kg.

Orcas show sexual dimorphism, which means that it is possible on the surface to distinguish whether they are male or female. It is quite easy, as adult males have a larger dorsal fin than the female, which can reach up to 1.8 m in length.

To conclude, we leave one more curiosity. Did you know that in captivity, due to the stress the animal is exposed to, the shallow depth of the tank and the temperature of the water, the dorsal fin tends to collapse?
In their natural habitat, orcas’ dorsal fins tend to be erect due to the fact that these animals can dive up to 600 meters deep, being exposed to colder temperatures and increased pressure.
We also leave a suggestion about the problem of orcas in captivity. On Netflix, you can watch the documentary “Blackfish” to learn more about this beautiful species.

Bibliography

Stredulinsky, E.H., Darimont, C.T., Barrett-Lennard, L. et al. Family feud: permanent group splitting in a highly philopatric mammal, the killer whale (Orcinus orca). Behav Ecol Sociobiol 75, 56 (2021).

Deecke, V.B., Barrett-Lennard, L.G., Spong, P. et al. The structure of stereotyped calls reflects kinship and social affiliation in resident killer whales (Orcinus orca). Naturwissenschaften 97, 513–518 (2010).