Deep dive…into False killer whales

While their name suggests otherwise, false killer whales are actually dolphins. They’re highly social and playful, often found hanging out with other species (particularly bottlenose dolphins).  

False killer whales have long and slender bodies – usually black or dark grey with lighter areas on their undersides – and they have narrow pointed heads with a prominent melon. They also have no beaks, sharp teeth, long S-shaped pectoral fins and a tall, tapered dorsal fin.  

The species looks similar to pygmy killer whales but they’re much bigger and have those unique looking pectoral fins. They get their name because the shape of their skulls is similar to that of killer whales (orca). That’s where the similarities end because killer whales have a very different appearance overall to false killer whales.  

There are some similarities to pilot whales, which is why there is another name for this species – false pilot whales.  

Social bonds are super important to this species. They’re usually found in groups of 10 to 40 dolphins, though they do sometimes join with other pods to form super pods of hundreds of animals.  

A study in Hawaii showed that false killer whales remained around the island chain for a minimum of 20 years and formed stable associations with other individuals for at least 15 years.  

Sadly, because they are so attached to each other, false killer whales have a tendency to beach in large groups when one or more individuals strand themselves (whether due to illness, injury or their navigation getting disturbed).   

The species swims quickly, sometimes leaps out of the air, bow rides and is often seen approaching vessels. It measures up to six metres in length and can weigh up to 1.3 tonnes.  

The relationship between false killer whales and bottlenose dolphins has been captured by the team behind Blue Planet II. The two species were filmed off the coast of New Zealand, gathering together in great numbers.  

A Massey University research project, which took place over 17 years, delved deeper into why false killer whales and bottlenose dolphins off New Zealand like to hang out together and what activities they do.  

Not only were they seen hunting together but they socialised, travelled and rested together over long periods of time (sometimes years) and over long distances. Later research and underwater filming by the BBC has shown that both species are actively involved in the herding of prey, even though bottlenose dolphins target the smaller kahawi and false killer whales prefer the larger kingfish.  

They work cooperatively to enable the other species to capture their prey, and vice versa. The same research showed, for the first time, that false killer whales often rest at night and may enter shallow bays to do so.  

Found in tropical, warm and temperate waters all over the world, false killer whales are often found in the deeper waters. This means there’s still a lot to learn about the species.  

A lot of what we do know comes from research of the population of false killer whales living in shallower waters off Hawaii.  

Areas where the species are found include the Gulf of Mexico, New Zealand, Peru, Argentina, South Africa, Australia, the Sea of Japan, Philippines, the Bay of Biscay, Red Sea ad Mediterranean Sea.

They’re also spotted in the warm Gulf Stream waters off the east coast of the U.S. and also off the West Coast (as far north as British Columbia in Canada). They are also found in the Mariana Archipelago and in American Samoa.  

It’s difficult to estimate the global population of false killer whales, as they live so far out to sea. They are listed as Near Threatened on the IUCN Red List of Threatened Species and the Hawaii population is designated as Endangered on the U.S. Endangered Species Act.

False killer whales mostly eat large fish and squid. They eat bigger fish (such as tuna and mahi mahi) than many other dolphin species do. 

Like other cetaceans, false killer whales can become entangled in fishing gear which goes on to cause injury, fatigue, comprised feeding, and sometimes even death.   
 
They are often viewed as a nuisance by fishermen when they steal fish from longlines and this had led to direct kills in some fisheries, including in Japan, St Vincent and Taiwan.  

Climate change and pollution are a threat to all whales and dolphins because of the loss of habitat as waters become warmer.   
  
Plastics and micro plastics, along with chemical pollutants, entering into the water system are a serious threat to all creatures in our ocean.

As false killer whales are near the top of the food chain, they accumulate a lot of toxins from the marine environment. This can result in diseases and reproductive issues.

False killer whales are one of the species targeted by the dolphin hunts in Taji, Japan, and as mentioned previously, they are sometimes killed by fisheries when they steal fish from longlines.

Two false killer whales in Hawaii carry scars from large shark bites, indicating that large sharks target the species sometimes. An attack by orcas has also been observed in New Zealand.