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.

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.

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.

A diver in British Columbia has been handed down the largest ever fine for getting too close to orcas.
A diver in British Columbia has been handed down the largest ever fine for getting too close to orcas.

Diver Fined CAD 9,000 For Swimming Too Close to Orcas

A scuba diver in British Columbia, Canada, has been fined a record 12,000 Canadian dollars ($9,250) for approaching a pod of orcas too closely.

In British Columbia, vessels must keep at least 200 meters away from orcas and in southern B.C. coastal waters between Campbell River and just north of Ucluelet, vessels must keep 400 meters away. Vessels must be at least 100 meters away from all other cetaceans.

Common dolphin (NOAA NMFS/Wikimedia Commons/Public Domain)
Common dolphin (NOAA NMFS/Wikimedia Commons/Public Domain)

Share your views on Scotland's first cetacean conservation strategy

Focusing on nine of the most commonly found dolphin, whale and porpoise species in UK waters, the strategy has been developed by the Scottish Government, in collaboration with the UK Government, the Welsh Government and the Northern Ireland Executive.

Its objective is to ensure the effective management to achieve and maintain the current favourable status of the nine species. It highlights certain pressures where further research or extra management measures may help to improve the conservation of marine mammals.

Mmo iwdg / Wikimedia Commons / CC BY-SA 3.0
Long-finned pilot whale cow with her calf, off the coast of Ireland. Photo by Mmo iwdg / Wikimedia Commons / CC BY-SA 3.0

Buoy in Celtic Sea tracks oceanic noise

Equipped with an autonomous hydrophone, the buoy's function is to conduct for the first time real-time acoustic monitoring of the water's cetaceans to assess how oceanic noise pollution affects them. 

Deployed as part of the Smart Whale Sounds project, it will also track the distribution and behaviour of whale species in real-time and be used to train machine learning models to identify different species' calls. 

Swimming with dolphins
Swimming with and learning from dolphins

Learning the swimming secrets of dolphins and whales

This scenario may one day become reality. And to be efficient, such robots would need to be maneuverable and stealthy, and be able to closely mimic the movements of the marine creatures.

Scientists like Keith W. Moored are working on the next generation of underwater robots by studying the movements of dolphins and whales. "We're studying how these animals are designed and what's beneficial about that design in terms of their swimming performance, or the fluid mechanics of how they swim."