Published Date: 2002-12-09 23:50:00
Subject: PRO/AH/EDR> Flying squid, domoic acid - USA (California)
Archive Number: 20021209.6025
FLYING SQUID, DOMOIC ACID - USA (CALIFORNIA)
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A ProMED-mail post
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Date: 9 Dec 2002
From: A-Lan Banks <A-Lan.Banks@derwent.co.uk>
Source: Monterey County Herald [edited]
<http://www.montereyherald.com/mld/montereyherald/news/local/4699798.htm>
Now, 4 months after truckloads of jumbo flying squids beached
themselves and died in San Diego, 2 Monterey Bay-area scientists have
joined the search for an explanation. The pair are investigating the
possibility that the squids were disoriented by domoic acid, a
naturally occurring toxin that kills dozens of marine mammals each
year. Mary Silver, a biological oceanographer at the University of
California at Santa Cruz, is analyzing pieces of the beached squids
to find out whether they ate something containing domoic acid.
William Gilly, a mollusk specialist at Stanford University's Hopkins
Marine Station in Pacific Grove, is trying to find out whether domoic
acid affects squids at all. The answer is worth finding out for
several reasons, Gilly said: It could affect the fishing industry.
There is a possibility that people might ingest the dangerous,
sometimes deadly, toxin while enjoying a squid platter. And squids
are important to the rest of the ocean and the food chain. They eat
smaller animals and are eaten in turn by whales, dolphins, fish and
birds.
"The squid population is important because it's a major player in the
ecosystem of the ocean," Gilly said. "It's important to learn more
about what affects squid and makes them have strange behaviors."
The state Health Department tests Monterey Bay regularly for domoic
acid levels. Earlier this year, there was enough domoic acid in
Monterey-area waters to close down the sardine fishery, according to
the state Department of Fish and Game.
Domoic acid doesn't affect sardines, but the fish carry it in their
intestines, potentially affecting people who eat them. The toxin
causes a disease called amnesiac shellfish poisoning, which can cause
permanent brain damage and death.
Domoic acid produced by one species of diatoms (microscopic organisms
that float in the ocean) races up the food chain from diatoms to fish
to big mammals such as sea lions and dolphins. The naturally
occurring chemical comes and goes, and no one is sure what makes
diatoms produce it.
Nor does anyone know how many 2-foot-long squids made up the 14 tons
of flesh along San Diego's coast in late July 2002. Jumbo flying
squids are native to waters off Baja California and only come as far
north as San Diego once every few years. This year there are schools
in the ocean off of Monterey, and some years they get as far north as
Oregon.
Squid authority Eric Hochberg, a curator at the Santa Barbara Museum
of Natural History, has been hunting for clues to the mass mortality.
He's pored through historic photographs and records that date back
200 years in his search for evidence of past strandings of the jumbo
flying squids, which can grow to be more than 10 feet long. His
search has turned up nothing.
"There is nothing that I had information on that was as massive a
stranding or mortality event as occurred in La Jolla in July," he
said. Hochberg said he doesn't know why the squids stranded, but
domoic acid is a good possibility.
The first known domoic acid outbreak was in eastern Canada in 1987,
when 3 people died and more than 100 were sickened after eating
mussels contaminated with domoic acid. This spring, diatoms produced
huge amounts of domoic acid in California waters, more than has ever
been recorded, said John Heyning, a marine mammal biologist at the
Natural History Museum of Los Angeles County.
Almost 100 whales and dolphins beached in Southern California because
they had domoic acid poisoning, Heyning said. Of the whales that
beached in Southern California, 3 were Cuvier's beaked whales, which
are known to eat jumbo flying squid. Heyning is leading a National
Marine Fisheries Service investigation into the marine mammal
beachings.
Nobody knows whether domoic acid can make squids sick. That's what
Gilly, the Stanford biologist, wants to find out. "Squid have
receptors in the nervous system that are a target for the domoic
acid. So if it can get into the squid nervous system, it could cause
a problem," Gilly said. Gilly has one of his graduate students at
Stanford testing how market squid, a different species from jumbo
flying squid, react when domoic acid is placed on a neuron in its
system.
The one type of neuron tested indicates that squids are sensitive to
domoic acid, but less sensitive than mammals, he said. But, he said
that squids could have a half dozen other receptors that no one has
looked at yet.
"But what it does in the blood of a living squid, we don't know,"
Gilly said, but surmised that the toxin could interfere with motor
control. That might make the squids clumsy in the water and more
prone to beaching. He said he wants to feed toxic krill to squids in
the lab to find out how it affects them.
There are several other possibilities for why the squids beached,
said Hochberg, the Santa Barbara curator, but none seems any more
likely than domoic acid. One theory is that the squids were following
grunion, a fish that comes up onto the beach to spawn. It is probably
the culprit in several smaller beachings, Hochberg said, but most of
the squids he dissected had empty stomachs.
Disease was another possibility, but the squids didn't look sick, he
said. "From all of the animals that I've looked at, there's no gross
pathology that you'd say they have some contagious parasite or some
problem," he said. Some researchers suggested that dolphins herded
the squid onto the beach, but Hochberg said that most dolphins "would
not handle squid that are as big as these are. So I have my doubts on
that."
On the other hand, if it was domoic acid, sea gulls should have died
from eating squid on the beach. Sea gulls were eating the squid, but
no one has reported unusual bird deaths. If scientists know what
caused the beaching, they can find out how to keep it from happening
in the future, said Greg Helms of The Ocean Conservancy in Santa
Barbara.
"Were they poisoned or somehow damaged by something out there and, if
so, what was it?" Helms said. "Or is it just Mother Nature doing her
thing?"
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See Also
Mammal, bird die-off, domoic acid - USA (CA) (02) 20020708.4702Mammal, bird die-off, domoic acid - USA (CA) 20020526.4323
Dolphin/sea lion die-off, domoic acid - USA (CA) (02) 20020426.4035
Dolphin/sea lion die-off, domoic acid - USA (CA) 20020422.4011
Shellfish ban, domoic acid - Canada (NB) 20020422.4010
Domoic acid, razor clams - USA (Washington) 20020405.3886
Dolphin die-off, domoic acid - USA (Calif.) (02) 20020331.3846
Dolphin die-off, domoic acid? - USA (California) 20020325.3817
2000
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Sea lions, seizures, domoic acid - USA (Calif.) 1998 20000107.0018
1999
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Domoic acid 19960209.0275
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