Summary Report of the 2016 Commercial Fishery for Razor Clams (Siliqua patula)

Category: Commercial Fishing / Shellfishing

Published: September 2017

Pages: 9

Author(s): Zach Forster


Executive Summary

Fishery Objectives and Preseason Planning

After an abrupt end to the 2015 season due to biotoxins, which resulted in loss of over half of the available digging days as well as the recall of product, harvesters and buyers advised using caution when considering a season in 2016. Due to the unlikelihood of the fishery opening in the spring of 2016 no public meeting was held, instead fishery managers solicited individual harvesters and buyers for their input on the 2016 season.  Harvesters remained optimistic that there may be some opportunity in 2016 but at the same time expressed concern about the potential loss of investment in license fees, and boat and equipment maintenance if the season was to but cut short again.  Buyers had reservations about opening up the fishery with biotoxins levels so close to the closure level especially given the variability in recent samples. Ultimately, an emergency closure which could result in product recall was a given priority over lost revenue from no season at all.  When it became apparent that a spring fishery was not going to open combined with buyer concerns with the poor post-spawning condition of clams harvested in the summer, fishery managers explored for the first time the option of a fall fishery. However, concerns over the continued poor condition of the clams and the occurrence of a new HAB event in the fall meant a fishery was never realized in 2016.

Biotoxin Sampling

Before the fishery opens, the Washington Department of Health (WDOH) protocols require two sets of razor clam samples be collected and results of the marine biotoxin tests must be below the federally established action levels.  These sets of samples must be collected seven to ten days apart and before the planned opener.  Each sample collected must test below 20 parts per million (ppm) for domoic acid, below 80 micrograms per 100 grams of meat tested (µg/100g) for paralytic shellfish poisoning (PSP) and below 16 micrograms per 100 grams of meat tested for Diarrheic Shellfish Poisoning (DSP).  Domoic acid (DA) is caused by the diatom Pseudo nitzschia (P-n), PSP is caused by the dinoflagellate Alexandrium catenella, and DSP is caused by the dinoflagellate Dinophysis.  Monitoring of biotoxin levels continues once the fishery is underway with fishery samples collected from dealers every seven to ten days. 

Biotoxins have impacted the commercial razor clam fishery in the past.  Commercial harvest in 1992, 1993, 1999, and 2015 was closed due to elevated levels of domoic acid (Table 5).  In 2015 an in season closure due to DA on May 8th caused WDOH to order all clams harvested on May 7th to be recalled and destroyed. The first razor clam biotoxin sample from the Willapa Spits was collected on February 10th with results above the action level. The next two samples collected at the end of February and beginning of March were both below the action level of 20ppm which was encouraging for an on time season opener, however the next sample collected on March 20th was above the action level at 30 ppm DA. Recall that it takes two consecutive samples below the action level to open a fishery.  On April 10th after a season delay had been announced staff collected an expanded set of samples from three different areas of the spits with results all above the action level.  Clams continued to test above the action level until the first week in June when all three areas tested at or below19 ppm DA.

Phytoplankton Monitoring

WDFW conducts routine monitoring of the surf zone phytoplankton assemblage as part of the Olympic Region Harmful Algal Bloom (ORHAB) project.  This monitoring program provides resource managers an early warning on harmful algal bloom events.  The Pseudo-nitzschia cell counts taken on the ocean beaches at Long Beach (6 miles south of the detached spits) and at Twin Harbors (8 miles north of the detached spits) are shown in Figure 1.   In the spring of 2016 cell counts remained low, it must be noted that DA levels in clam tissue were elevated prior to the first increase of Pseudo-nitzschia (P-n) cells on adjacent beaches in June.  Near the end of June cell counts exceeded the action level (50,000 cells/L), however there was very little particulate DA measured in the cells.  Cell counts remained relatively low, at or slightly below the action level, until the first week in September when counts quickly increased to over 2.5 million cells/L.  By the end of September cell counts were back to nearly zero however a strong storm and south winds the first week of October pushed another bloom of P-n that had been seen earlier as far north as Newport, OR into Washington waters resulting in yet another increase in DA in clams collected from the adjacent recreational beaches.

It is important to note that the HAB event that led to the closure of the Washington commercial razor clam fishery was very wide spread, also closed were the southern Washington and Oregon recreational beaches.

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