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San
Diego, CA (June 4, 2002)
-- Since February, more than 500 sick California sea lions
have come ashore in Southern California. This unusually high
number of strandings caught the attention of marine mammal
scientists who traced the condition to a biotoxin called domoic
acid.
What
is domoic acid?
Domoic
acid is produced by algae that occur naturally in the ocean.
(In this case, the alga has been identified as the diatom
Pseudo-nitschia australis.) When environmental conditions
are favorable, algae can overgrow, creating what is known
as a “bloom” or “red tide”. When an alga blooms, the many
tiny plants can produce large amounts of the domoic acid toxin.
Chemically,
domoic acid looks like this:
How
does the domoic acid get into sea lions?
Sea lions don’t eat the algae — but fish do. And sea lions
eat the fish that eat the algae. How can this be deadly? Because
domoic acid is a toxin that becomes concentrated as it travels
through the food chain. This process is called bioaccumulation.
In 2002, the domoic acid problem is occurring almost exclusively
in common dolphins and sea lions. A large part of these animals’
daily diets is composed of filter-feeding anchovies and sardines.
Other animals have been spared because they are eating different
food items.
How
does domoic acid affect sea lions?
When sea lions eat fish that contain domoic acid, toxin gets
into their bloodstream and affects their brains. Domoic acid
damages a part of the brain called the hippocampus. Sick sea
lions show a variety of symptoms: they may vomit, they may
have seizures, and they become depressed and comatose. Some
of the animals have died on the beaches. Most of the affected
sea lions are pregnant females. These animals often deliver
their babies early. Because these moms are sick, they cannot
care for their babies.
What
does SeaWorld do for sick sea lions?
SeaWorld has a stranded animal program designed to assist
ill or injured animals found on the beaches of SanDiego County.
This facility is one of many in California that belong to
the Marine Mammal Stranding Network under the National Marine
Fisheries Service. Here at SeaWorld the animals are treated
to control seizures. Because the animals do not eat or drink
when they are comatose, they receive fluid support — a lot
like getting an IV at the hospital. The animals are protected
so that they don’t drown and so they don't get too hot or
too cold. When they start to come around, they are fed and
brought back to strength so that they can swim and catch fish
to feed themselves in the wild. Once they are back on their
feet (or flippers, as the case may be), the animals are released
back into the wild.
Where
is this algal bloom and will it hurt the animals after they
are released?
The algal bloom is believed to have originated in the
Monterey and Morro Bay area of the coast and extends down
to Los Angeles County. Although sick sea lions have been found
on the beaches from Baja California to Santa Barbara, we believe
that releasing animals off the San Diego coast puts them in
safe feeding grounds.
What
can the public do for these animals?
If you find a sea lion on the beach that is shaking or
seems disoriented it may be poisoned with domoic acid. It
is important to remember that these are wild animals. Contact
the lifeguards or the local stranded animal rescue center
to get the proper personnel to help the animal. The contact
numbers for the stranding facilities/rescue personnel in southern
California are:
Santa
Barbara Marine Mammal Center - Santa Barbara
(805) 687-3255
Fort
MacArthur Marine Mammal Care Center - San Pedro,
(310) 548-5677
Friends
of the Sea Lion Marine Mammal Center - Laguna Beach,
(949) 494-3050
SeaWorld
- San Diego
(800) 541-7325
For
more information check out these Web sites:
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