UAF experts say shellfish toxin likely to be a problem again this year

05/28/2011

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NR: SG-2011/NR323

Anchorage, Alaska—Ocean conditions that last year triggered algal blooms and outbreaks of paralytic shellfish poisoning (PSP) appear to be present again this summer, according to experts at the University of Alaska Fairbanks School of Fisheries and Ocean Sciences.

"Ocean conditions are about the same as last year, so I expect PSP levels could be on the high side again," said Ray RaLonde, the aquaculture specialist at the Alaska Sea Grant Marine Advisory Program in Anchorage.

PSP is a naturally occurring toxin produced by some species of microscopic phytoplankton that appear in blooms each summer as the ocean warms. The PSP toxin concentrates in shellfish as they filter-feed on the algae. People who eat shellfish contaminated with PSP can become severely ill and sometimes die.

Across coastal Alaska, hundreds of residents and visitors harvest clams, mussels, geoducks and other shellfish from local beaches, either recreationally or for subsistence. And almost every year, people become sick from eating PSP-contaminated shellfish they harvest. Occasionally, someone dies. Alaska's Department of Health and Human Services considers PSP to be a public health emergency.

According to the agency, people with early symptoms of PSP experience tingling of the lips and tongue, which may begin within minutes of eating poisonous shellfish, or could take an hour or two to develop. Symptoms may progress to tingling in fingers and toes and then loss of control of arms and legs, followed by difficulty in breathing. Death can result in as little as two hours.

Already this year, one person who ate clams collected from a beach near Ketchikan became sick with symptoms of PSP, according to the Alaska Department of Health and Social Services.

"The bloom appears to be increasing in intensity in Ketchikan," said Ginny Eckert, associate professor of fisheries at the University of Alaska Fairbanks School of Fisheries and Ocean Sciences. "We are actively collecting seawater samples to look for PSP in the water, and to identify the phytoplankton that produces the PSP toxin."

Eckert is part of the Alaska Harmful Algal Bloom (AHAB) monitoring and early warning program, a partnership between the university, state and federal agencies, and area commercial shellfish growers and subsistence shellfish harvesters. The program monitors algal blooms commonly associated with outbreaks of PSP and other marine toxins, in an effort to detect toxic algal blooms before the toxin reaches shellfish. Commercial shellfish producers use the information to protect their product from PSP.

As he does every year as summer kicks off, RaLonde advises coastal residents and visitors not to eat untested shellfish harvested from Alaska beaches.

"Without proper testing, you can never really know if the shellfish are safe to eat," Ralonde said.

RaLonde said results of tests for PSP on shellfish collected during 2010 from several beaches popular with recreational and subsistence harvesters found PSP levels to be many times higher than is considered safe by the U.S. Food and Drug Administration. Health officials measure PSP in micrograms (mcg) of PSP per 100 grams of shellfish tissue. The FDA safe limit is 80 mcg per 100 grams of tissue. During 2010, testing found the following:

Location Shellfish Levels of PSP
per 100 grams of tissue
Haines blue mussels 2,793 mcg
Juneau cockles 2,044 mcg
Kodiak butter clams 862 mcg
Sand Point butter clams 926 mcg
King Cove butter clams 641 mcg
Akutan blue mussels 390 mcg
Unalaska blue mussels 2,695 mcg
Atka blue mussels 641 mcg

Last summer, a Haines resident who died after eating crab viscera believed to be tainted with PSP had "symptoms consistent with PSP," according to the Alaska Department of Epidemiology. The official cause of death was heart failure, though PSP could not be ruled out as a contributing factor, according to the agency. In nearby Juneau, one woman died last year after eating PSP-laden cockles harvested from a local beach.

RaLonde plans to test shellfish again this year. He can't say for sure if PSP levels will be higher, lower, or about the same as last year.

"The environmental conditions that produce the toxic algae blooms containing PSP and the ocean currents that spread the blooms are complex," said RaLonde. "Making accurate predictions about when, where, and to what degree an outbreak will occur is just not possible."

RaLonde's advice: "Play it safe. Don't eat any untested shellfish harvested from any beach in Alaska. Chances are too great that you will get sick, and worst-case, you could die."

Alaska's Department of Health and Human Services has issued at least two warnings already, advising people not to eat untested shellfish harvested from Alaska beaches. Read one of the warnings online at: http://www.hss.state.ak.us/press/2011/PSPwarning_PR_051111.pdf

The state's warning says all locally harvested shellfish—including clams, mussels, cockles, oysters, geoducks and scallops—can contain PSP toxin.

RaLonde said shrimp, abalone, sea cucumbers and other species that do not filter-feed are considered safe.

Unlike other shellfish, crabs and geoduck clams accumulate PSP only in their digestive organs. To ensure they are safe to eat, RaLonde suggests removing the digestive organs and washing thoroughly with clean water before cooking. For giant scallops, only the adductor muscle is free of toxin.

All shellfish sold at wholesale and retail markets require PSP testing and only safe products are certified for human consumption.

Alaska does not have a PSP testing program for recreational or subsistence harvested shellfish and does not certify any beaches as free of PSP. Shellfish harvested anywhere can potentially have dangerous levels of PSP.

For more information, visit Alaska Sea Grant's PSP information and resources web page.

The Alaska Sea Grant College Program is a statewide marine research, education, communication, and extension service at the University of Alaska Fairbanks, School of Fisheries and Ocean Sciences. Alaska Sea Grant is funded by the National Oceanic and Atmospheric Administration, in partnership with the University of Alaska Fairbanks and private industry.

The Alaska Sea Grant Marine Advisory Program is a statewide university extension and technical assistance program that helps Alaskans wisely use, conserve, and enjoy Alaska's marine and coastal resources.