For the first time since records began, a pod of orcas has reached the coasts of northern Chile. And there, marine biologists have taken advantage of this unique opportunity to study a hitherto unknown population of this elusive species, which still hides many mysteries for science. The orca is the super predator of the seas, above even the white shark in the food chain, but little is known about the hunting habits and techniques of many of its populations, which tend to live far from the coasts.
In 2018, a group of anchovy fishermen in the Chilean bay of Mejillones saw a pod of killer whales up close for the first time. Hundreds of sea lions were entering and exiting the nets, attracted by the typical fish of the area. It was then that they saw these great ocean predators arrive — led by a female, which scientists later named Dakota—, who took advantage of those moments of anchovy fishing to approach the boats and corner the sea lions until they died. The photos and videos of the sightings, uploaded to Facebook, later served the researcher Ana María García Cegarra and her team to begin investigating.
García Cegarra, a marine biologist at the University of Antofagasta, feels that “it is a dream come true to study these cetaceans in the wild. It is not easy to see orcas so close to the shore,” she says, as they can swim thousands of kilometers in the open sea in search of food. García Cegarra has led a study, published this Thursday by the magazine Frontiers in Marine Sciencewhich combines our own surveys and testimonies from the local population.
Orcas are cosmopolitan animals, present in all the world’s oceans, but there is not enough data to know their conservation status, according to the IUCN Red List of Threatened Species. In this case, the researchers tracked the hunting preferences of the pack (2020-2023) between the Chilean regions of Antofagasta and Coquimbo in waters influenced by the Humboldt Current that travels from Patagonia to Ecuador. “Understanding their role in the sea is essential to generate conservation strategies for this little-known species,” explains García Cegarra.
In the article they have just published, this cetacean expert and her colleagues also document with drones the first image of successful orca hunting. dusky dolphins“We have seen males with offspring chasing each other, as a kind of game,” explains García Cegarra. This new evidence about feeding habits can help, according to the authors, to understand how populations in the southern hemisphere are linked.
“Orcas in the southern hemisphere have been studied mainly in Antarctic waters, but further north there is a lot of misinformation,” says García Cegarra. In total, five ecotypes have been found in this part of the world, such as type A orcas (whose diet is marine mammals) and type B1, which prefer fish. Although analysis is still needed to determine which of these the pod belongs to, this marine biologist believes they are A. “We need a biopsy to analyse their genetic data,” she says, which will not be an easy task because they are very intelligent and agile animals.
Pollution and collision risks
Bruno Díaz, scientific director of the organization Bottlenose Dolphin Research Instituteagrees with García Cegarra on this point, since orcas are difficult to study, although he highlights that the article represents “a starting point. It is a foundation stone for future studies. It would be interesting to see how regularly they visit that area and how they get their favorite prey in that case,” says the expert, who did not participate in the research. In addition, in the observations, the researchers noted that the orcas share the prey with their offspring, which indicates that they are reproducing, but they are not sure of the survival rate, an aspect that worries the scientist due to the high levels of contamination, especially in Mejillones.
“We believe that maritime traffic and the risk of collision are threats to the orcas, as is pollution. The bay is a port terminal for the transport of goods and mining supplies and we are concerned about the survival of the offspring, because the mothers can accumulate metals and other contaminants that adhere to the fat and breast milk,” warns García Cegarra. Mejillones is one of the five sacrifice zones in Chile. For decades, the environment has been steadily affected by industrial activity and the presence of at least eight coal-fired power plants that should close before 2030, according to the decarbonisation plan promoted by the Chilean government.
Along these lines, the director of expeditions for the NGO Oceana, Ricardo Aguilar, mentions that in general in coastal areas where orcas live there is already “a fairly high level of interaction with humans. For example, in the case of Spain, with the population of orcas in the Strait of Gibraltar, they tend to interact with ships that pass through the area. What should be done is to adopt measures so that they can be preserved and that there is no such impact from humans,” says Aguilar, who was not part of the study.
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