- But until now, no data existed for our killer whales in the North Atlantic, including those in Eastern Canada and the Canadian Arctic.
- The accumulation of these synthetic contaminants is also creating health risks for the killer whales.
Forever chemicals
- In the last century, these chemicals were mass produced and used in a wide range of applications, such as industrial processes or agriculture.
- But research conducted in Sweden in the late 1960s revealed that these chemicals accumulate in living organisms and persist in the environment.
- The chemicals bind to fats and increase in concentration as they move up the food web, impacting dolphins and whales the most.
A gradient of contamination
- Our study, focusing on 160 killer whales, reveals a concerning pattern of PCB contamination accross the North Atlantic.
- The concentrations vary significantly across the North Atlantic, ranging from a staggering 100 mg/kg in the Western North Atlantic, to around 50 mg/kg in the mid-North Atlantic.
You are what you eat
- Killer whales that primarily feed on fish tend to have lower contaminant levels.
- On the other hand, those with diets focused on marine mammals, particularly seals and toothed whales, show higher levels of contaminants.
- Risk assessments suggest that killer whales in the Western North Atlantic, and specific areas of the Eastern North Atlantic where they have mixed diets, face higher risks, directly linked to what they eat.
Disappearing sea ice
- Killer whales’ large dorsal fin has traditionally prevented them from navigating dense sea ice.
- But the melting of sea ice has allowed killer whales to access a new habitat with new prey species.
Maternal transfer means females are less contaminated
- Male killer whales appear to be more contaminated than their female counterparts, thanks to the transfer of contaminants from adult females to their offspring during gestation and lactation.
- As she feeds her young ones, she may pass on as much as 70 per cent of these stored contaminants.
Urgent action
- In response to these findings, urgent action is needed to protect North Atlantic killer whales and their ecosystems.
- The 2001 United Nations treaty’s objective to phase out and destroy PCBs by 2028 is slipping out of reach.
Chemical pollution has been identified as one of the nine global threats to wildlife, as well as human health in modern times. It is time to give our planet — and killer whales — the relief they need by reducing existing contaminants through concrete actions.
Anaïs Remili does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
