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October clam dig needs one more clean test

Observer staff report

Published on September 21, 2017 10:21AM

LUKE WHITTAKER/Chinook ObserverIf a second round of marine toxin testing comes out all right next week, there will be a razor clam dig in Pacific County on Oct. 6 and 7. These diggers enjoyed a beautiful day on the Long Beach Peninsula earlier this year.

LUKE WHITTAKER/Chinook ObserverIf a second round of marine toxin testing comes out all right next week, there will be a razor clam dig in Pacific County on Oct. 6 and 7. These diggers enjoyed a beautiful day on the Long Beach Peninsula earlier this year.

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LONG BEACH — It won’t be certain until after a second round of testing next week, but so far things are looking good for a razor clam dig on the Washington coast Oct. 6 and 7.

The wildly popular recreational harvest depends on there being safe levels of a naturally occurring toxin, domoic acid, which is generated by a type of marine algae. The Washington State Department of Health defines the safe level of domoic as 19 parts per million or less in the meat of clam samples gathered on the beaches of the outer coast.

Tests by DOH earlier this week found safe levels of domoic in clams in the state’s two most productive clam beaches, both in Pacific County.

“Results reported by DOH for clams collected Sunday the 18th from three areas at Twin Harbors beach were all 10ppm or below, results for clams collected on Monday the 19th from four areas on Long Beach were all 8ppm or lower. We will be collecting additional samples next Monday the 25th for the second sample to open the beaches on the scheduled dates,” WDFW Coastal Shellfish Biologist Zach Forster said this Wednesday. Forester is based at the Willapa Bay Field Station in Nahcotta.

Results from the second set of samples are likely to be available Wednesday, Sept. 27. If those tests find safe levels that are not spiking upward, a previously announced clam dig will commence:

• Oct. 6, Friday, 7:49 p.m.; -0.4 feet; Long Beach, Twin Harbors, Copalis, Mocrocks

• Oct. 7, Saturday, 8:33 p.m.; -0.7 feet; Long Beach, Twin Harbors, Copalis, Mocrocks

Long Beach, as defined by WDFW, comprises the ocean seashore in south Pacific County, while Twin Harbors spans the beach from the mouth of Willapa Bay to about Westport. The two beaches generate most of the state’s recreational clam harvest. The two other beaches, Copalis and Morocks, are north of the mouth of Grays Harbor. A fifth, smaller clamming beach inside Olympic National Park won’t be open for clamming at least through the end of the year.


Troubling sign


Although domoic levels currently are low, offshore waters have recently experienced a boom in the marine organism that sometimes produces the toxin.

This type of algae, Pseudo-nitzschia, isn’t itself harmful. It forms part of the base of the ocean food chain that feeds many other things, including clams. There are dozens of different species of Pseudo-nitzschia, some of which under certain conditions produce domoic acid as a byproduct. This toxin doesn’t harm algae or clams, but has a variety of detrimental impacts on humans, ranging from intestinal upsets to death. Marine mammals and birds also are harmed by the toxin. It’s most notorious as the cause of amnesiac shellfish poisoning, which in acute cases can permanently damage the ability to retain short-term memories.

WDFW has observed elevated cell counts of Pseudo-nitzschia on both south Washington beaches in recent weeks, however recent tests show that they are not producing much domoic acid either in Washington or the North Coast of Oregon, something Forester described as encouraging.

“Our surf zone monitoring program detected a significant increase in Pseudo-nitzschia cells last week on both of these beaches with cell counts of over 1.5 million cells per liter, which is up from around 150,000 cells/L the previous two weeks,” Forster said on Sept. 18. As of Sept. 14, these the cells were not producing much domoic acid, he said.

Oregon Department of Fish and Wildlife performs the same tests in Clatsop County and have found a similar increase in Pseudo-nitzschia cells, along with a higher reading for particulate domoic acid than has been observed north of the Columbia, Forster said. This “is concerning for our two beaches given the recent change in weather,” he said.


Mystery mechanism


It remains uncertain why Pseudo-nitzschia sometimes produces domoic acid.

“One aspect of these toxic algal blooms, which affect wildlife as well as economically important fisheries, remains a mystery: how do the algae make domoic acid and what triggers its production?” Tim Stephens of University of California Santa Cruz wrote in an Aug. 23 article.

Researchers are looking a range of factors, including changes in ocean chemistry and temperature. Pseudo-nitzschia may produce the toxin as reaction to environmental stress, such as running short on trace elements in seawater that they need to survive. UC Santa Cruz researchers have found Pseudo-nitzschia doesn’t produce domoic acid on its own, but may require genes from a type of marine bacteria to generate the toxin. University researchers are using a $130,000 NOAA grant to try to understand how this works.

“One part of the new research project will focus on unraveling the details of how algae and bacteria interact to produce domoic acid,” Stephens reported. “Another part of the project will use monitoring data from Monterey Bay to assess how this interaction fits into the larger context of the many physical and environmental factors, such as water temperature and nutrient levels, also known to influence toxic algae blooms. Sorting out the effects of multiple factors, all varying simultaneously in a complex system, is a challenge.”


Season prospects


A summary of last season and an overview of the recently completed razor clam stock assessment are available in WDFW’s 2017-18 Razor Clam Management Plan at wdfw.wa.gov/fishing/shellfish/razorclams/seasons_set.html.

According to WDFW stock assessments, the number of harvest-size clams on Long Beach dropped from 12,239,000 in the 2016-17 season to 3,062,000 for 2017-18. A total harvest of about 873,000 is planned for 2017-18, compared to last season’s actual harvest of 1.6 million in a season shortened to 11 days due to domoic toxin.

Millions of clams are believed to have died of natural causes between the pre-season 2016 stock assessment and now, WDFW Coastal Shellfish Manager Dan Ayres said: At least in part, by an extended period of low salinity in surf zone ocean waters, particularly those near Long Beach and Twin Harbors.

Twin Harbors beach has an estimated 1,678,000 harvest-sized clams now, compared to 4,742,000 a year ago. Twin Harbors’ allowable harvest for 2017-18 will be about 507,000, compared to last year’s actual harvest of 870,000.

In addition to the forthcoming Oct. 6 and 7 dig, proposed razor clam digs through December are listed below, along with evening low tides and beaches:

• Nov. 2, Thursday, 6:03 p.m.; 0.1 feet; Copalis

• Nov. 3, Friday, 6:47 p.m.; -0.7 feet; Long Beach, Twin Harbors, Mocrocks

• Nov. 4, Saturday, 7:31 p.m.; -1.2 feet; Long Beach, Twin Harbors, Copalis

• Nov. 5, Sunday, 7:16 p.m.; -1.4 feet; Long Beach, Twin Harbors, Mocrocks

• Dec. 1, Friday, 4:42 p.m.; -0.3 feet; Copalis

• Dec. 2, Saturday, 6:49 p.m.; -1.9 feet; Long Beach, Twin Harbors, Mocrocks

• Dec. 3, Sunday, 6:15 p.m.; -1.6 feet; Long Beach, Twin Harbors, Copalis

• Dec. 4, Monday, 7:02 p.m.; -1.8 feet; Long Beach, Twin Harbors, Mocrocks

• Dec. 31, Sunday, 5:12 p.m.; -1.2 feet; Long Beach, Twin Harbors, Copalis, Mocrocks

For more information about recreational razor clamming, visit WDFW’s website at wdfw.wa.gov/fishing/shellfish/razorclams/.



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