What causes shellfish beds to close? What happens when they open?

In Saturday's Kitsap Sun is an article about the Puget Sound Partnership, now in its 5th year, measuring the health of Puget Sound and improvements with various indicators [click here for article]. Well known in developing any strategy to address an issue is that measurable points have to be pre-determined in order to show strategies implemented are successful in their implementation. One of the primary indicators now being used is to restore 10,800 acres to "harvestable" condition by 2020 [click here for "indicators"]. A recent report shows 1,384 acres have been opened to shellfish farming.

Shellfish beds are closed for long periods by the Department of Health for one primary reason: measurement of fecal coliform above a certain level over a period of time. Immense resources are expended by the Department of Health each month to obtain water samples from Puget Sound which are, in turn, analyzed. If elevated levels are found over a period of time there begins a determination of what the source is. Typically the "low hanging fruit" is assumed to be defective septic systems, dairy or cattle farms.  Other sources include seals, Orca, and waterfowl. The percentage of each is an ongoing challenge to determine.

Farmland adjacent to Samish Bay

For years closures have been addressed in a number of ways. If failing septic systems are suspected, counties are asked to send out inspectors to individual parcels for testing. Counties are also able to create, in some cases mandated, "shellfish protection districts" such as Oakland Bay, Burley Lagoon and Henderson Inlet [click here for information on how shellfish districts are created]. Waste water treatment plants can be upgraded. Dairy and cattle farms divert waste from streams. In Thurston County, residents along part of Henderson Inlet will be assessed a fee if they own a septic system. All incrementally help to improve levels of fecal coliform.

What Else Causes Closure?
Closure is not only tied to fecal coliform. Shellfish being "filter feeders" graze on whatever is floating by in the water. Important to shellfish consumption is the naturally occurring bacteria Vibrio parahaemolyticus (Vp), a bacteria which lies dormant in sediments until warmer summer months trigger a bloom. In addition to bacteria, phytoplankton also create unsafe shellfish. Diseases contracted toxins created by phytoplankton include Diarrhetic Shellfish Poisoning (DSP) and Paralytic Shellfish Poisoning (PSP).

 

Vibrio Parahaemolyticus

In the case of Vp, there is an annual outbreak every summer which each year causes illness from oyster consumption. Washington and Texas lead the nation in illness from Vibrio. Last summer, Samish Bay, Hood Canal, Totten Inlet, Hammersley Inlet, and Oakland Bay were all closed due to Vp.

 

Life Cycle of Alexandrium Bacteria

DSP in Puget Sound had not been been considered a problem until last year and is now of such concern the Department of Health recently purchased a $350,000 testing unit which allows faster detection and closure of shellfish beds. The increase in concern is also due, in part, to new studies suggesting that exposure to low levels of DSP may increase the risk of cancer.

Last summer, a family was hospitalized after contracting PSP from shellfish harvested from Discovery Bay. The Public Health Officer commented, "It's noteworthy in terms of the severity of the symptoms." Recent testing found unsafe levels of PSP toxin in geoduck from intertidal areas of Discovery Bay and subtidal tracts, resulting in their closure to commercial harvesting.

What does it mean?
One result of Puget Sound's water being safe to grow shellfish is the safe consumption of shellfish growing naturally on the tidelands as they have for millennium. Another is to profit from growing shellfish on the tidelands. Profits from the latter have driven many efforts to achieve a more healthy Puget Sound. However, it is also the latter which has transitioned from a historical role of being a benign "preferred use" of the tidelands as the Shoreline Management Act envisioned. To many, as the Shoreline Master Programs are being updated, it is becoming clear the fragmentation and piecemeal development of the shorelines should now be focused on the shellfish industry.

Being a "preferred use" no longer means having a free hand to use whatever structures and methods there are at hand to convert tidelands to a shellfish farm. Reopening shellfish beds which have been closed should not mean a wholesale conversion to monolithic populations which would not survive without the current structures used in shellfish farming. Restoration of natural shellfish beds is important. It is why the measurements of what makes up the "Human Qualities of Life" are so critical to develop, now.