It was sad and disturbing to find out that seven Puget Sound
killer whales have died so far this year.
We haven’t had that number of deaths since 1998 — the year after
19 orcas visited Dyes Inlet between
Bremerton and Silverdale. To those who study these whales, the
orcas aren’t just seven animals in a herd; they are individuals
with unique characteristics; they are members of an extended family
that stays together for life.
Ken Balcomb of the Center for Whale Research
believes the deaths are related to a shortage of chinook salmon
seen this year from California to Washington to British Columbia. I
went into some detail about this in a story in
today’s Kitsap Sun. I also included a brief “obit” on the
animals that died.
I would like to take a moment to remind myself and others that
it is unlikely that the deaths were caused by a single factor. I
have long been intrigued by the prospect of synergism in these
animals, and I would hope that researchers will one day be able to
accumulate enough data to support or deny this hypothesis.
What I’m talking about is this: Researchers have promoted three
principal causes of the decline in Puget Sound whales, officially
known as Southern Residents. They are toxic chemicals (such as
PCBs) that have accumulated in their bodies, lack of prey (chinook
primarily), and stresses caused by noise, whale-watching boats and
other things. For more info, check out the
recovery plan for the Southern Residents.
Follow this train of thought:
- PCBs and other chemicals are believed to damage the orcas’
immune systems and reduce their ability to fight off disease.
- If the animals are not getting enough food, they draw upon fat
reserves in their blubber. Metabolizing these fats tend to release
the toxic chemicals into their bloodstream, exposing their immune
systems to more chemicals and further increasing their risk of
- Although the whales seem accustomed to whale-watching boats,
anything that causes them to use up excess energy to replenish
their energy supplies by hunting for food cannot be a good thing,
especially in times of a food shortage. Uninformed boaters
sometimes interfere with the whales’ travel during foraging, and
noise caused by boats is believed to decrease their efficiency in
finding fish through echolocation (their natural sonar
In my mind, all of these factors tend to work together. What is
often hard to sort out is whether an animal dies of starvation or
disease. When food is in short supply, disease may set in before an
animal literally starves to death. Also, especially for a hunting
species, a disease can reduce their ability to get food, so the
outcome is the same. For many species, a higher-level predator may
kill an individual that is starving or diseased. But with an animal
at the top of the food web, such as killer whales and humans, the
dynamics may be different.
I guess I’m just trying to point out that it could be an
oversimplification to say the whales starved to death, even if food
were a certain factor.
With regard to news sources, I have to confess that this story
of the seven missing whales has been in the wind since Oct. 8, but
I missed it. Howard Garrett and Susan Berta of Orca Network put something on their
Web site, but I overlooked it. Richard Walker, editor of the
Journal of the San Juans had talked to Ken Balcomb about that time,
but I missed his story until someone pointed it out to me.
Finally, several people have mentioned the coincidental
stranding of a killer whale on the island of Kauai in Hawaii. Diana
Leone of the
Honolulu Advertiser reported that the 18-foot female was
emaciated and had “cookie-cutter shark bites” and whale lice, all
signs that it had been sick for some time.
CNN posted a user-generated video
about the whale.
I understand that researchers are trying to see if the female
orca, who was euthanized, can be connected with previous
I looked up a 2004
Marine Mammal Stock Assessment Report (PDF 56 kb) for a little
background. It says Hawaiian killer whales are rarely seen, but the
best population estimate is 430. Minimal genetic data indicate that
the animals may be related to Gulf of Alaska transient killer
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