Threats for Orcas
- Elding's research team
- May 22
- 6 min read
Welcome orca-lovers to the last blog of this Orca series. Here we will introduce you to the threats orcas and other cetaceans face on a daily basis. If we can all become more aware of these threats and then make small changes to our lives it could make a huge difference to our environment and all the animals living in it, including us.
Entanglement
As lots of unused or broken fishing gear ends up in the ocean, instead of the trash, animals can get entangled in it, this means, they swim close to see what it is and then the lines rap themselves around a body part of the animal. In a previous blog we have looked at entanglement of humpback whales including an example of when we saw it happen on a whale watching tour in December. Two things can then happen if they can’t get rid of it or there is no human intervention to help.
The lines will slowly cut into the skin, then through the blubber (the fatty tissue) and lastly into the muscle. This will cause infections and a lot of pain.
The lines (and maybe attached buoys) will also slow the animal down, tire them and prevent them from diving. This results in not being able to hunt for food anymore. They will slowly starve.
Not only fishing gear that got thrown away is a threat to Orcas, also longlines used during fishing activities. Killer whales try to scavenge a quick snack here but sometimes end up being entangled in them.
As we spoke about in the first blog, orcas can use echolocation. Unfortunately, this sometimes doesn’t work on the fishing lines due to the materials they are made from and their thinness.
Noise Pollution
Orcas will use sound for echolocation but also for communicating with each other. In the water there are a lot of natural sounds from waves, wind, earthquakes, volcanic activity and other marine species. Orcas and other cetaceans have evolved with these natural sounds so are well adapted to it. But in the last century human-made sounds have been increasing dramatically. These sounds are often much louder too. These sounds could be from sonar or even just the constant sound of a boat’s engine.
Sounds such as sonar used in naval activities result in:
Interfering with their communication and navigation. They now cannot hear each other or can’t find their prey via echolocation. If there is reduced communication, pod members may become separated, especially juveniles and calves
They may also be displaced due to the increased sounds, so migrations could be impacted, as well as changes in behavior involving feeding and mating.
Mass strandings could even occur due to the disorientation caused by the sounds.
Devastating impact is also caused because of seismic surveys. When they´re searching for oil and gas, powerful blasts will be shot at the sea floor as often as every 10 seconds. Because of these underwater “explosions”, they may suffer from hearing loss and ruptured organs, which results in their death. Decompression sickness could happen if the frightened whales return from a dive too quickly just like with humans! The blasts can also kill plankton meaning there are further disruptions to the food chain.
Climate change
As we all know, one of the impacts of climate change is that ice will melt, therefore there are new habitats to be occupied and new food sources to exploit. There are negatives to this as well. For example in 2024 a pod of orcas got trapped in ice close to Japan. One explanation of this could be they were exploring a new area then the ice came in quickly and trapped them. Maybe they didn’t know the area well so were also unaware of potential threats here that would usually be passed down the matriline.
PCB (Polychlorinated Biphenyls)
Killer whales are one of the most highly PCB contaminated mammals on the planet. PCBs used to be used in building materials and electrical equipment. However, in the 1980s they became banned in Europe before a global ban came into place in 2004. Despite this, PCBs still continue to be in our environment. They can accumulate in the blubber of marine mammals including orcas. They can impact reproduction (infertility), the immune system and cause neurological problems. Females rely on their blubber to produce milk for their calves. But then the calves receive the PCBs too, the concentrations are up to 18x higher in the calves due to their young age and developing bodies. Orcas in the North Atlantic are particularly threatened by PCBs. For example, an orca called Lulu seen in Scotland had PCB levels at 100x the safe limit! Around 50% of orcas around the world experience high PCB levels.
Whaling, Live Captures and Captivity
In the past, orcas were hunted and captured for marine parks, often torn away from their pods in traumatic ways. This happened to Keiko. Captivity then confines the orcas to small spaces which leads to lots of stress and shorter lives. They will also display repetitive and unnatural behaviors.
In the North Atlantic, killer whale numbers could have recovered after the end of the whaling and live captures in the 1980´s, but there are new threats like chemical pollution, anthropogenic noise and increasing unregulated subsistence whaling in Greenland that could hamper this rebound.
In some parts of the world orcas are still hunted and even still sold to captivity in places such as Greenland, Japan, Indonesia, the Caribbean islands and Russia. Compared to other cetaceans whaling of orcas was much rarer. But they were still hunted for meat or oil. This is mostly illegal now, with the exception of these places where it is usually on a smaller scale.
Collapsed Dorsal Fin
The dorsal fin of an Orca plays a vital role in the hydrodynamics of these animals and has a thermoregulatory function. It provides stability while swimming and allows them to dissipate excess heat. This anatomical structure may contribute to increased success when hunting prey, escaping predators or controlling body temperature. It also may be an indicator for females if the male is fit, when it has a vertically straight dorsal fin.
So, when Orcas have collapsed dorsal fins, the causes could be reduced intake of nutrients - because of lack of food, or reduced blubber thickness due to physical injuries or illness - which result from for example long line entanglement, oil spill or trauma and malformation of the vertebral column, exposure to stress or simply just age.
In captivity they collapse because of insufficient movement and exposure to warm air almost constantly. Almost all male orcas in captivity experience this; it is very rare for orcas in the wild to have collapsed dorsal fins.
Plastic pollution
There are “more plastic than fish” in the oceans. It is estimated there are over 5.25 trillion pieces of plastic in the ocean, this is a really big problem! Plastics have been found all over the ocean including at the deepest parts of the Mariana Trench. Orcas may then directly ingest plastic or it could come indirectly through their prey. 100,000 marine mammals are killed each year due to plastic ingestion. This ingestion could cause dehydration when the plastic absorbs water, starvation and malnutrition. Whale carcasses have been found with many kilograms of plastic in their stomachs. Plastic can also cover body parts that are vital for survival, like the mouth or fins.
Southern Resident Killer Whales
Unfortunately, the Residents in the Salish Sea, off the coast of Washington and British Columbia face what is called “Bright Extinction”. This is when a well-studied species are declining in plain sight. They’re in deep distress for a few reasons. Firstly, the previous captures for amusement parks in the 1960´s and 70´s reduced their numbers drastically. They also suffer frequent interruptions of their foraging activities by ship traffic and the toxic chemicals (PCBs) that accumulate in their blubber, they struggle to recover their numbers. To compound their population decline there is also a lack of their primary prey, Chinook Salmon. This species of salmon shrank in numbers from a combination of habitat loss, climate change, commercial fishing and dam construction. These are man-made problems. It would be the first extinction, where every individual’s name is known! They consist of 3 pods: the J-, K- and L-Pod. In the beginning of 2025, another calf of the J-Pod died, potentially because of a lack of food and therefore the mother couldn´t produce enough mother milk for her calf. Just like in 2018, when another calf died, the mother was seen carrying the dead body with her. Both times the mother did this for over 2 weeks. Other members of the pod helped her, so she could rest and eat.
As you can see, orcas and other marine life have to face a lot of dangers and threats in their daily lives. If everyone contributed whenever possible by reducing their use of plastic, cutting back on fish consumption, and lowering their carbon footprint, it would make a huge difference. If everyone stood up and tried to do the right thing, the world would be a better place for animals like orcas and humans as well.
And like Sir David Attenborough said: “For if we save the sea, we save our world”
Thank you for reading along Orca-lovers, I hope you enjoyed this orca blog series!
Kylie Veal
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