As part of last month's expedition in the Beagle Channel, a team of researchers recorded an unusual interaction between spiny porpoises (Phocoena spinipinnis) and Peale’s dolphins (Lagenorhynchus australis) in a kelp forest in the Strait of Magellan using a drone. 
 

The recording was made by Chilean marine biologists Nicolás Muñoz and Constanza Alarcón in the kelp forests of the Agua Fresca sector, in the Strait of Magellan, during a field campaign of the marine mammal acoustic monitoring network. The initiative is led by the Centro de Investigación Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL) of the Universidad Austral de Chile (UACh) and the Alfred Wegener Institute (AWI) of Germany. It is also sponsored by Chile's environment ministry.
 

"During the sailing trip we were observing a group of Peale’s dolphins that habitually use the kelp forest in the area and I could see that one of the individuals had a mainly greyish coloring. At first I thought it was a Chilean dolphin, which are not so unusual to see in interaction with Peale’s dolphins. However, as I moved the drone closer, we were able to corroborate that it was a spiny porpoise," says Muñoz.
 

The audiovisual producer adds that "this generated a lot of excitement among those of us in the boat, because spotting this species is very difficult, a little swell is enough to make finding it an almost impossible task. What we were able to see in this interaction between the porpoise and the group of Peale’s dolphins were approaches where apparently no rejection or territoriality was generated by the Peale’s dolphins that frequent the area on a regular basis. For several moments the porpoise swam alongside the pod of dolphins, which included a calf."
 

The value of the recording lies in the fact that it is the first time an interaction between the two species has been recorded. It is also the first time a harbour porpoise has been captured moving widely in a kelp forest. "It's possible that these events happen more often than we think, it just takes a bit of luck to coincide the presence of the animals, the weather conditions and having the equipment at the time," Muñoz says.

Both the Peale’s dolphin and the spiny porpoise belong to a large group of toothed cetaceans called odontocetes. However, porpoises belong to a different family of dolphins called phocenids and are related to beluga whales and narwhals. One of the big differences between the two species lies in their teeth: dolphin teeth are cone-shaped, while porpoise teeth are flattened and spatula-shaped. 

As Muñoz explains, "the spiny porpoise gets its name from a series of protuberances on the upper part of its dorsal fin, which is difficult to see in the field because it sticks out very little of its body when it emerges to breathe. In contrast, the southern dolphin has a very pronounced, backward-curved dorsal fin, which is very useful for identification purposes."

Conservation
Dr Diego Filun, who leads the acoustic monitoring of marine mammals for Centro Ideal, says that in general there is little information on the harbour porpoise. 
 

"There are studies that describe its occurrence in Peru and throughout Chile. In general, this species prefers slightly deeper places than the Peale’s dolphin, so to have this record of the two species interacting among kelp forests is certainly something striking. The fact that these interactions occur in the Strait of Magellan demonstrates the importance of this place for both species and that this place is not only important for feeding and movement of whales, but also for small cetaceans," he says.
 

The scientist emphasizes the importance of the use of new technologies, such as drones or bioacoustics to make records of this type. "We hope that with the project we are carrying out we can continue to record new milestones and that the information we generate, in addition to disseminating it to the public, can be used in public policies and conservation plans."