These orcas, living in the krill- and anchovy-rich waters of the Humboldt Current, have previously been observed using fishing boats to help them capture sea lions. Now, they have been observed to be skilled hunters of dusky dolphins, a behavior documented for the first time by a team led by Dr Ana García Cegarra of the Universidad de Antofagasta. The findings reveal that the orcas share their prey within their pods, suggesting complex social behaviors and shedding light on their ecological role.

The expedition was led by the Schmidt Ocean Institute, in partnership with Ocean Census and the University of New Hampshire’s Center for Coastal and Ocean Mapping/Joint Hydrographic Center. The mission focused on exploring and mapping seamounts in international waters, about 900 miles off the coast of Chile.

The sightings, documented in a study by Amy Rose Coghlan and Naiti Morales, took place during a period of unusually warm sea surface temperatures, a condition that has been linked to the expansion of tiger shark habitats in other parts of the world.

Orcas have long been considered a single global species, with different forms in different regions, known as “ecotypes.”

However, scientists have long recognised the differences between resident and transient orcas, known as Bigg's killer whales, in the North Pacific. Resident orcas maintain close-knit family pods and prey on salmon and other marine fish, while Bigg’s orcas roam in smaller groups and hunt other marine mammals such as seals and whales.

Ground-breaking research has revealed that Pacific kelp forests are much older than previously thought, reshaping our knowledge of marine ecosystems.

Originally thought to be a relatively recent occurrence in ocean history, kelp forests are now considered ancient entities, with origins dating back millions of years. This revelation comes from the analysis of fossil records and advances in dating techniques, allowing scientists to peer back through time.

Researchers from the University of British Columbia (UBC) have uncovered compelling evidence of a potentially new population of killer whales in the Northeastern Pacific, distinct from known orca ecotypes. 

This discovery, documented in a recent study published in Aquatic Mammals, is based on observations of 49 orcas exhibiting unique hunting behaviours, including predation on sperm whales and sea turtles, off the coasts of California and Oregon.

(VIDEO: Researcher Al Dove collecting a blood sample. Video by Dr Simon Pierce)

DS: What were some of the challenges encountered when doing underwater ultrasounds? How did the team overcome them?

Although manta rays are readily capable of long-distance movements of hundreds if not thousands of kilometres, most populations appear to be philopatric (tending to return to or remain near a particular site or area—ed.) with few examples of long-distance dispersal.

Oceanic manta rays, the largest ray species, were listed as threatened under the U.S. Endangered Species Act in 2018. In 2019, their threat category increased from vulnerable to endangered on the International Union for the Conservation of Nature’s Red List.