Subscribe to North America's Longest Established Scuba Diving Magazine
Conservation Marine Life

Orcas: Sentinels for Ocean Health

By Jean-Michel Cousteau and Holly Lohuis

Dr. Peter Ross, marine mammal toxicologist, explains his research to Jean-Michel Cousteau, Holly Lohuis and the OFS expedition team. Photo: Carrie Vonderhaar, Ocean Futures Society

L41, a 43-year-old male orca from the Southern Resident L Pod is missing and feared dead. This is just one more blow to the endangered orca population in the Puget Sound region.  For whale researchers, whale enthusiasts and local residents of the Pacific Northwest, these killer whales are like family and when one goes missing, it is heartbreaking news for us all to comprehend.  

When L41 was last sighted in August 2019, he was showing signs of being underweight but still swimming with his extended family as he had for much of his entire life. If he remains missing, the population of the endangered southern resident orcas will only be 72 animals, the second lowest number of individuals since the Ken Balcomb with Center of Whale Research and his team began its population census over 45 years ago.  Today, these three orca pods, J, K and L, are some of the most watched orcas in the world.  From the important research conducted by multiple organizations and institutions, we know that L41 and the late J1 fathered most of the calves born in to the three southern resident pods since 1990. Unfortunately, today these endangered orcas are struggling for survival because of three main threats: lack of their favourite prey, King or Chinook salmon; increase shipping noise and disturbance by boats; and the bioaccumulative effects of industrial chemicals passing up the food chain and impacting these top predators.  And what has been recently documented is the real and unfortunate fact that, from 2008 to 2014, nearly 70 percent of all known orca pregnancies in these southern resident orcas pods have failed.


Orcas, also known as killer whales, are the most cosmopolitan species of dolphin. They are found from the Arctic to the Antarctic and live in different cultures comprised of complex societies with strong family bonds. They learn important survival and social skills from the older females and many orcas stay with their mother for their entire lives. We have learned much about these complex social ties by studying orcas in the wild for over 50 years.  What we have come to appreciate is how these apex predators help us gauge the health of their oceanic environment by how well the different populations are either thriving or failing over time. Orcas are important sentinels of ocean health.

The plight of endangered southern resident orcas became a personal story for my team and I when back in the summer of 2008 we worked with orca biologists and marine mammal toxicologists filming orcas in five countries for a PBS TV special Call of the KillerWhale. There was a consistent theme amongst the orca experts: the health of the ocean is directly linked to the success or decline of orca populations studied around the world. 

I will never forget standing on a rocky beach in British Columbia with Dr. Peter Ross, then a marine mammal toxicologists with Canada’s Department of Fisheries and Oceans and now Executive Director of Coastal Ocean Research Institute at the Vancouver Aquarium, when he told me all about the impacts of industrial, synthetic, man-made chemicals that are leeching into the marine environment and are having detrimental effects on animals, especially those at the top of the food chain.  

“Many of our industrial chemicals are dissolving in fat, and fat of course is the currency of energy in a food web. So the chemicals are magnifying up the food web, reaching often very high levels in fish-eating or marine mammal eating organisms.

“In these areas, in these species of killer whales, we see population level consequences. We see reduced reproduction. We see increased mortality. We see increased incidences of diseases. And in putting together the collective results of these multiple lines of research, we can start to understand what chemicals such as PCBs [polychlorinated biphenyls, which were banned in 1976 but still present in the environment] or PBDEs [polybrominated diphenylethers, a class of chemicals mainly used as flame retardants] might be doing to animals at the top of the food chain, like the killer whale. And of course we share the environment with marine mammals. If a marine mammal is heavily contaminated with industrial chemicals, that’s starting to tell me something is amiss with our environment. It means our activities are impacting on the health of the ocean and it’s not good for the marine mammal in question, it’s not good for the environment, and it’s not good for the humans who rely on these same food webs.”

Research published in September 2018 in the journal Science suggests that we stand to lose half of our planet’s orcas in three to five decades due to lingering PCBs and other persistent organic pollutants (POPs) in the environment.  PCBs were once used in capacitors, coolants, and oil paints, until they were deemed so dangerous that their manufacture was banned. But much of the stockpile, up to 80%, has yet to be destroyed. PBCs are considered a legacy class of chemicals that will be present in our environment for decades still to come. 

As science uncovers more information regarding the impact of untested chemicals in household products, it is becoming increasingly necessary to reform and modernize governmental policy when it comes to the manufacturing of potentially harmful chemicals. Most governments require zero testing before manufacturers incorporate chemicals in products. This creates a reactive government, designed only to clean up the mess caused by harmful chemicals instead of preventing damage from happening to the environment. 


Time is of the essence. We didn’t know before about the impact of industrial chemicals on the oceanic food web, but now we do and it’s not an issue of pointing fingers or accusing anybody. Now that we know the consequences, we need to immediately change. It’s time to find ways to prevent such chemicals from entering the environment in the first place, to find alternatives, and to anticipate problems before they occur. We cannot wait to find a cure for dangerous products after they are in the environment and in us. Since first learning about the health risks of PBDEs as endocrine disrupters in both orcas and humans back in 2008, most of these toxic chemicals have been banned after both Dr. Ross’ research and research conducted on human health demonstrated that these chemicals were doubling in concentration every 3-5 years. That is the good news. But unfortunately there are other non-tested, potentially harmful and toxic chemicals that have replaced PBDEs in the market place.

Orcas are one of my favourite animals in the ocean. I feel extremely privileged to have seen orcas on many of my expeditions in different locations around the world. I also appreciate the opportunity to learn from the passionate biologists and scientists who are helping us gain a better appreciation of the complex societies and important role orcas play as indicator species of ocean health. I will never forget my encounter with orcas in Papua New Guinea back in 1992 when the orcas swam down to deep depths below us, out of view, and would come back towards the surface to show us their successful hunt of reef sharks. Or the time when I was whale watching in the Monterey Bay National Marine Sanctuary and I witnessed the supreme hunting skills of a pod of orcas taking a three month-old gray whale calf away from its very protective 30-ton mother.  And just recently I learned about a family reunion of three transient (marine mammal eating) orca pods off the Santa Barbara, California coast as they worked together to hunt some California sea lions. I know there is still so much we need to learn about these amazing animals.  

As my good friend and orca expert in New Zealand, Dr. Ingrid Visser reminds me, “If we understand orcas better then we are going to love them more and if we love them more, then yes, we are going to look after them… I hope.” 

My greatest hope as divers and ocean advocates is we all collectively take responsibility to protect the one thing we all have in common: our home, our ocean, and our one water planet. From supporting sustainable seafood, minimizing our single use plastic use and being very respectful around wildlife; may we all continue to seek opportunities to explore our underwater world in hopes we continue to learn and feel inspired to take daily actions that help ensure a sustainable future for us all, including our counterparts in the ocean, the Orca. 

0 Comments Leave A Reply

Leave a Comment

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.