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Southern Resident Killer Whales survive being the most contaminated mammals on earth?

By Hardy Jones, BlueVoice co-founder

When I sat down with my old friend Ken Balcomb to discuss the plight of the killer whales he has studied for more than twenty years. I was in for a terrible shock.

In 1982 I made my first trip to the San Juan Islands in Washington State to meet Ken, regarded today as one of the foremost authorities on killer whales on earth. Ken was using dorsal fins and saddle markings to identify individual whales.

I was fascinated to compare the techniques he used with killer whales with the approach we had in our studies of spotted dolphins in the Bahamas. The killer whales who pass through the San Juans are known as J, K and L pods and together are called the southern resident pods because they spend large parts of the year in the inland waters of the Pacific Northwest. They come here through the Straights of Juan da Fuca on their way up to the Fraser River in Canada following schools of salmon on which they feed.

Though the pods often travel together each has its own unique approach to feeding on salmon and each pod has a distinct vocal repertoire. It is clear that information is passed from one generation to another – an indication that these orca have a culture.

Ken’s dog Suchi attracts whales’ attention.

These are some of the best-known and most beloved marine mammals on earth. The identities of all members of the pod are known, in some cases the family tree can be identified going back decades.

They may also be the most contaminated marine mammals on earth. And from 1995 – 2000 ten of the males in J, K, and L pods died. While there is no absolute proof that they died from contaminants such as PCBs, their carcasses did contain astronomical levels of these deadly toxins.

I learned these heart breaking facts while Ken and I screened film I had shot in the late 1980s and mid 90s. He told me all the males in the footage we were screening had died since those marvelous days when we had followed them on their feeding runs through Haro Straight and Boundary Pass.

As Ken told the story “From ‘95 on we started having a pretty serious mortality. What’s really interesting about that footage is that virtually all the adult males that are in there are now deceased. . . just in a period of less than 20 years we’ve lost most of the adult males in the whole southern resident community.”

“We’ve attributed most of the mortality to the PCB levels in the tissues. Their immune systems are depressed, much like aids, so they don’t defend themselves against common bacteria. And also their reproductive systems don’t develop.”

Later we headed out on the water. As we approached turn point a mother moved past us close to the boat with her calf nursing. The reason females are surviving and so many males are not is that when a mother orca nurses her calf she offloads huge amounts of chemicals such as pcbs that are stored in her lipid rich milk. Often first-born calves do not survive. But second and third born survive after the mother is unburdened of much of her toxic load.

These high food chain predators live just off Seattle, Washington. The killer whales here probably pick up their burden of contaminants from local sources. But industrial chemicals are contaminating the ocean ecosystem worldwide and are spread on the winds and tides. Some PCBs in these waters have come from as far away as China.

The tragedy of the resident pods is the flip side of the joy I experience being with killer whales in the wild. Having a personal knowledge of these whales, knowing their names and thrilling to them as they travel, feed, and socialize makes their deaths a personal experience of deep sadness.

The toxic chemicals that have so impacted the southern resident pods are not just a threat to fish and marine mammals – it is now clearly a threat to humans.

But there is some good news. Despite the loss of so many – particularly males and calves, the southern resident pods are now increasing in number . . . from a low of 76 to a current population of 87. Four calves were born during the summer and fall of 2004 and as of February 2005 all had survived.

Visit the Center For Whale Research


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