Among all ocean predators, Killer Whales are largest and arguably some of the fiercest. Easy to recognize, thanks to distinctive black and white markings, these whales face an uncertain future, due to an invisible threat that has been building in the oceans since the Second World War. What's killing killer whales? Read on to learn more.
A Deadly Threat
During WWII, industries began to use chemical flame retardants, including PCBs. Though PCB's were found to be harmful to humans and other life, and despite the fact PCB's were banned by governments around the world in the 1970's, their legacy continues.
Orcas hunt a variety of prey, including rays, sharks, and other large marine life including grey and blue whales, which is partly why they are threatened by high PCB levels. As long-lived apex predators, they are extremely sensitive to changes in their prey. As it turns out, orcas have been absorbing pollution from the water, as other animals do, and feeding on fish that have consumed polluted prey. Orcas ultimately end up ingesting all the pollution in that food chain, via a process known as bioaccumulation.
The most worrisome trends are developing in orca populations around New Zealand and the rest of the Northern Hemisphere, particularly around the north Pacific, off the Arctic and Canada. High PCB concentrations have been found in killer whale carcasses discovered in the Southern Hemisphere, as well.
Other toxic chemicals are contributing to orca death, including PBDEs, which have traditionally been used in electrical devices and in foam used to fill furniture. Of all these, PCB and PBDEs seem to be worst, as they interfere with thyroid function and cause problems with Vitamin A metabolism. They also have negative effects on immune function, reproductive development, and neurologic processes.
Marine experts categorize these chemicals and others as POPs, or Persistent Organic Pollutants. They accumulate in fatty tissue, and high levels are found in the high-fat milk female cetaceans produce to feed their young. Through this process, called maternal transfer, young whale calves, particularly first-born calves, take in a huge amount of the mother's PCB body burden. Since PCBs are resistant to breakdown, and since they do not dissolve in water, the pollutants persist for generations. In fact, studies focusing on PCB levels within cetacean body tissues have shown levels have remained fairly constant since about 1997.
Killer Whales can travel for long distances, consuming a variety of prey animals along the way, and they are notoriously elusive, so scientists have had an understandably difficult time gaining as much insight as they would like to. These whales are found in all the world's oceans, and they rarely become stranded. As a species, they are doing quite well; however, the PCB problem is causing some developmental delays in young whales, meaning they take longer to grow to become skilled hunters fine-tuned for survival.
There is nothing we, personally, can do to eliminate the lasting legacy of PCB's and PBDE's, but we can do killer whales and other marine life a favor by steering clear of other known toxins which have yet to be banned. For example, styrene and BPA are two plastic toxins which are everywhere we look. By using your own purchasing power, you can help eliminate demand. Next time you're looking for a beverage or a snack, pick a drink in a glass bottle or an aluminum can, and choose a snack with minimal packaging. When you do your best to make choices that won't have a negative long-term impact on humans and animals, you choose in favor of a healthy future for everyone - including killer whales.