Aerial images comparing the sizes of adult male Bigg’s and Resident killer whales, both taken in the Salish Sea off southern Vancouver Island.

Orcas Are Possibly Two Distinct Species

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.

A pair of orcas in the Pacific Northwest. In the Pacific Northwest there are three types of killer whales: resident. transient, and offshore. Transient orcas are rarely observed. They move quickly through an area feeding on seals and other marine mammals.

Potential New Orca Population in Northeastern Pacific

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.

Lolita performs
Lolita performing (Averette at English Wikipedia/ CC BY 3.0)

Eviction Notice Served to Miami Seaquarium Amidst Controversy Over Animal Welfare

Miami-Dade County Mayor Daniella Levine Cava addressed the issue in a statement posted on social media platform X, revealing that The Dolphin Company had consistently fallen short in maintaining the premises and ensuring the safety and well-being of the animals under their care. She emphasized that the current state of the Miami Seaquarium is deemed unsustainable and unsafe.

Southern Resident killer whale holding in its mouth a harbour porpoise calf that was eventually drowned

Why are orcas killing porpoises?

A comprehensive study published in the journal Marine Mammal Science analysed over 60 years of recorded interactions between Southern Resident killer whales (SRKW) and porpoises in the Salish Sea. This endangered population of orcas, known for their fish-based diet, particularly Chinook salmon, has been involved in numerous incidents of porpoise harassment, leading to the deaths of many porpoises.

Possible explanations

The study proposes three main reasons for this behaviour:

Southern Resident orca harassing a porpoise
Southern Resident orca harassing a porpoise

Why Southern Resident orcas harass porpoises

A study in the Marine Mammal Science journal examines the question of why Southern Resident orcas in the Pacific Northwest harass and sometimes kill porpoises without eating them.

Such behaviour has been passed down through the generations and across social groupings, and has been recorded as far back as 1962.

The question of why comes to mind.

Not on the menu

Certainly not to eat them. Southern Resident orcas do not harass the porpoises to consume them.

Orcas photographed off the southern side of Unimak Island, eastern Aleutian Islands, Alaska
Orcas photographed off the southern side of Unimak Island, eastern Aleutian Islands, Alaska

Orcas battling strange skin disease

Scientists studying endangered southern resident orcas have noticed a steady increase of mysterious gray patches and gray targets (circular lesions which may appear on concentric rings – ed.) on the whales’ skin from 2004 to 2016. 

To date, researchers managed to identify six distinct types of lesions, with the two most common types being gray patches or targets. Some resemble tattooed skin.

They do not know the cause of the lesions and are worried that they could be due to underlying health problems in the struggling population.

A pair of southern resident orcas
A pair of southern resident orcas

Southern resident orca mothers pay higher price to care for sons

It turns out that raising sons takes a higher toll on southern resident orca mothers, when compared to raising daughters. So much so that the mother’s annual likelihood of successfully breeding is reduced by about half.

This is because the mothers share the fish they catch with their sons even after the latter become adults. The mothers would bite the fish they catch into two, consume one half and give the other half to their sons.

(In the case of their daughters, the mothers also share their food, but stop doing so when the daughters reach reproductive age.)

Orcas and humpbacks brawl

Whale watchers were making their way toward the U.S.-Canadian border in the Strait of Juan de Fuca when the captain spotted the group of whales. At first, whale watchers observed what they thought was a pod of roughly 15 Bigg’s orcas swimming and "being unusually active at the surface." Before long, it became apparent that two humpback whales were in their midst.


According to observers who came and went throughout the day, the intense encounter that unfolded included an astonishing three hours of breaching, tail-slapping and loud vocalizations.

Orcas hunt Great White Sharks

For several years, scientists have suspected that orcas have been killing and eating parts of great white sharks. Now, they have video evidence to prove it.

New drone and helicopter footage show a pod of orcas ruthlessly pursuing a great white shark in Mossel Bay, South Africa for more than an hour before going in for the kill. The video culminates with one of the killer whales gobbling up a large chunk of the shark's liver.