Three pods of killer whales in the Pacific Northwest have now earned the unfortunate title of being the most contaminated wildlife on Earth, according to a new study. These killer whales, known as southern residents, live in the coastal waters near the U.S.-Canadian border and survive almost exclusively on contaminated Chinook salmon. The salmon contain high levels of polychlorinated biphenols (PCBs) and other industrial chemicals, which accumulate in even higher levels in the killer whales. Researcher Peter Ross says whales are particularly sensitive because they eat massive amounts of fish over a long life – killer whales can live for 80 or 90 years – creating a massive buildup of toxins. That means the whales, particularly the southern resident population, have become some of the most contaminated marine mammals in the world [AP].
Researchers estimate that the southern resident killer whales carry 6.6 times more PCBs than a different group of whales just 200 miles to the north, known as the northern residents. They found that the Chinook salmon in the southern waters, including Puget Sound near Washington state, not only had the highest concentrations of contaminants but also the least amount of body fat. This means the southern residents are suffering a “double whammy” because they are forced to eat extra helpings of heavily contaminated salmon. Ross and his colleagues discovered that 97 percent to 99 percent of contaminants in the Chinook eaten by these whales originated from the salmon’s time at sea, in the near-shore waters of the Pacific. Only a small amount came from the time the salmon spent in rivers, although many of the rivers are contaminated, too, Ross said. “Salmon are telling us something about what is happening in the Pacific Ocean,” Ross said. “They are going out to sea and by the time they come back, they have accumulated contaminants over their entire time in the Pacific Ocean” [Scientific American].
The southern resident population, which is listed as endangered under US and Canadian law, now numbers 83, down from over 100 in the early 1990s. Although the decline cannot be attributed completely to contamination, researchers believe the PCBs are compromising the whale’s immune systems, making them more susceptible to infections. PCBs are a kind of endocrine disruptor, known to interfere with development, meddle with immune system function and cause a host of other problems. The Environmental Protection Agency banned most uses of PCBs in 1979; but the chemicals had been widely used in coolants, pesticides, plastics and other products and are extremely persistent in the environment, cycling through the food web for decades [Science News]. In the late 1980s, PCB contamination is believed to have contributed to a virus epidemic that resulted in a massive decline in European harbor seals.
According to the new study published in Environmental Toxicology and Chemistry, the southern resident males carry almost 150 parts per million of PCBs, the highest concentration recorded in a wild animal [Scientific American]. Female orcas tend to have lower concentrations of the chemicals because mothers offload them to their young, both in the womb and through breast milk. This means at a developmentally fragile time, young orcas get a hefty dose of poisons [Science News]. But researchers say cleaning up PCBs will be very difficult because the only way to get rid of the chemical is to incinerate it at very high temperatures.
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Image: iStockphoto
January 27th, 2009 at 8:41 am
Granted humans don’t eat nearly the amount of Chinook, but this does pose questions about the safety of this Pacific breed. Especially, since Wild Alaskan Salmon from the Pacific (Chinook included) are touted as being nearly contaminant-free as opposed to most of the farmed varities in the Atlantic.
January 27th, 2009 at 8:41 am
Misspelled “varieties.” Sorry.
January 27th, 2009 at 2:18 pm
Yes, that was one of my first questions after reading this too…what about all the salmon that people eat? Is it safe to eat?
I know this article is about the killer whales and how they are being polluted by the salmon, but it makes you wonder why the salmon is still on the market if it is so polluted?
As far as the killer whales – I hope there is something that can be done to help them!
January 28th, 2009 at 4:54 pm
I think we can assume that the salmon are probably not safe for people to eat. The better questions to ask ourselves, however, are 1. why do we as humans continue to be carefree about our destruction of everything we touch, and 2. how can we change this and make the world a better place?
January 28th, 2009 at 8:22 pm
I know that the U.S. has banned PCBs, but what about the rest of the world? DDT was banned many years ago in the U.S., but it is still used extensively in Africa and has showed up for years all over the world even Antarctica.
January 28th, 2009 at 9:47 pm
Way too many people on the planet!!
January 29th, 2009 at 4:49 am
I doubt very much that we, as humans, have anything to fear from consuming salmon. If you read the article carefully, it says that killer whales live up to 80-90 years and it is throughout those 80-90 years of consuming tons of salmon that they have become that poisoned. Throughout our lifespan however, we would only consume a minuscule quantity of salmon and have much less of a risk of becoming subject to contamination.
January 30th, 2009 at 4:27 am
I hear of all the industrial waste and “Great Garbage Patch” in the Pacific Ocean…but what about all those U-boats we sunk in the Atlantic 60 years ago? Didn’t they carry quicksilver in their ammunition holds? Plain and simple: we need to clean up the Oceans and stop raking the bottom for Crabs and Shrimp! Think with your head not with your stomachs.
February 5th, 2009 at 6:50 pm
I agree with Roger on most of his arguments, he’s right. But forget about about what happened 60 years ago, mother nature has dealt with that. nowadays polution has increased in such an inpropriate manner it cannot be dealt with.
We simply cannot clean up the oceans, by what we’re messing them up so easily.
Pierre, your oulook might be pretty much short on sight, if consider man’s problem to have trouble with eating contaminated salmon (solution is simple – don’t eat salmon), but this sign is a sign of a eco system collapsing…
The hunter gets killed of the prey!
Now look at us humans, we are the hunters, we are the end of the nuriture chain, we will consume all our own waste…
But we should try to avoid contaminated salmon… o_O
February 17th, 2009 at 4:48 pm
Not only do we need to clean up our massive mess. We need to create a sustainable lifestyle that doesn’t harm our ecosystem. For all of our intelligence, we lack wisdom. It doesn’t matter whether or not WE eat the contaminated salmon. The sum of all life on this planet is a single organism. When we harm just one piece, we harm part of ourselves. What other living thing does the damage we do?
Drastic cultural and lifestyle changes are needed. The first question is: “Can we change?” The next would be “How?”. And then we need to act. I’d say for one thing that any chemical that has an adverse effect on life shouldn’t be used. Unless it can be completely contained. But as any can see, we can’t contain our mess just yet.
February 17th, 2009 at 4:58 pm
Either that, or crazy advancements in technology. :P