Geoduck Farming: Environmental Issues

Sara Thompson

Editors note: This article is the third of a four-part of a series on geoduck aquaculture. The first focused on the hearing for a new farm on the west side of the Key Peninsula, the second reviewed the history of geoduck aquaculture. A final article on the economics of geoduck farming will be published next month. [UPDATE: you can read that article here]

What exactly is the environmental impact of geoduck farming? Oyster, manila clam and mussel aquaculture had been a part of Puget Sound for decades, but the ability to grow geoducks is a relatively new development.

As new farms were established in the mid 2000s, some illegally, communities worried that their shorelines were at risk. Concerns ranged from aesthetics and loss of recreational beaches to loss of habitat and the risks of PVC tubes used to protect the clams.

In addition to worries about the immediate impact of a geoduck farm on a local community, what might be the long term consequences? What are the cumulative effects of larger numbers of farms over decades?

The state Legislature passed a bill in 2007 establishing a fund to study the impact of geoduck aquaculture over the next six years. Sea Grant, a program that is a collaboration between the University of Washington and the federal government, was chosen to commission the research. A literature review and research report were published in late 2013 and an update on new research directions was published last month.

Geoduck farms cause changes in the local beach. But is change equivalent to harm? Are species at risk? As is true with most scientific research, answers are rarely black and white, and most studies lead to further questions.

Aesthetics are an ongoing concern. Most pictures shown by opponents to demonstrate the sight of PVC tubes that have become dislodged and litter beaches are from 2006 and 2007. Practices have improved to minimize the loss of tubes, and permits require crews to clean the beach after storms. The industry has developed mesh tubes that are less visible and don’t require nets over the tops.

Aquaculture advocates state that the tubes (used for the first year or two to protect young clams from predators) are visible only 5 percent of the time, but that probably underestimates the actual visual experience.

Low tides, when the tubes are visible, are at night during the winter but in daytime during the summer. This means that they are visible roughly 20 percent of the time during spring and summer months.

Opponents decry the trapping of birds in nets, though this is a relatively rare occurrence.

According to experts testifying on behalf of Longbranch Shellfish at a Shoreline Hearing Board appeal, PVC tubes appear to be relatively safe. The material is inert and sediment near the tubes has not shown any evidence of microplastics or leaching of toxins.

There is currently little or no evidence that the tubes or debris from the tubes (which sinks to the bottom of the Sound) would harm fish or birds. The actual volume of debris on the floor of the Sound is unknown, however.

The Sea Grant research studies looked at the impact of geoduck farming on the water, sediment, eelgrass and animals living in the sediment and at the surface. The studies were limited in overall scope, and although substantial negative impacts were not seen, there were clearly some differences between geoduck farms and adjacent beaches. Further research was recommended.

Laura Hendricks, of the Coalition to Protect Puget Sound, continues to be concerned about the impact of PVC debris and microplastics as the volume of farming expands. Wayne Daley, a former Boeing engineer who has a fisheries degree and has worked as a consultant since 1996, is critical of the Sea Grant-sponsored studies. He said that until the impact on forage fish (herring and sea lance) and phytoplankton on the near shore is understood, there should be a hold on additional farms.

How much aquaculture is too much? Are there any limits on the amount of shoreline that could be farmed?

Ty Booth and Dave Risvold of the Pierce County Land Panning and Services Department noted that although any landowner who owns tidelands could apply for an aquaculture permit, there are practical limitations.

First, there are physical characteristics of a given beach that may make geoduck farming in particular impossible. Second, the steps involved in applying for a permit are onerous, particularly for individuals.

The Department of Ecology recently informed counties that the process must include a conditional use permit —which requires review and approval by Ecology. But 60 percent of Washington tidelands are privately owned and there is no legislation that absolutely limits the number of farms in Puget Sound.

Booth notes, though, that between 1997 and 2005, six permits for geoduck farms were approved. Since that time, three have been approved by Pierce County and two are under appeal. Nine permits are pending, although some of those applications are old and may not be pursued.

Cumulative impact —looking at the effects of aquaculture over multiple harvests and taking into account the increased number of acres farmed —is now the key issue. It is included in shoreline master plans to assure that there is no net loss of ecological functions. “No net loss”is not defined in black and white terms, however.

Explained Perry Lund, Southwest Region unit supervisor for the Department of Ecology, “When we look at any permit, we have to look at the whole picture, and look not just at the specific project. We must take into account mitigation, restoration and the broader planning concepts within the Shoreline Master Program.

“Any project, whether it is putting in a septic system, a dock or bulkhead, or starting a geoduck farm, will cause a change but we want to assure as much as possible that it does not lead to a substantial negative impact,”Lund said.

What comes next? Work through Sea Grant continues, though it depends on funding from the state Legislature. Larry Seaquist wasinstrumental in getting recent funding for aquaculture research, and it is not clear who will continue to advocate for money since he lost his legislative seat in the lastelection.

Washington Sea Grant researchers are now concentrating on developing models to understand the effects of aquaculture on the food web; addressing thephysical, biological and chemical factors interacting with aquaculture (including development of an early warning system for ocean acidification); fullyassessing the economic impacts of aquaculture and spatial planning (extent of current farms, data on ecological sensitivity and otherconsiderations such as water quality, physical constraints, designated areas for other uses).

P. Sean McDonald, PhD, a UW researcher working with the Sea Grant program, said, “The Puget Sound shore is a hard place for theanimals that live there. Storms, surf and flooding may be as disruptive to their environment as geoduck farming. But weneed to understand if there is a tipping point, where the effects over time or due to increased extent are causing harm to our beaches.

“We are using the data from the Sea Grant-sponsored geoduckprojects to model how much aquaculture might be too much or whether thereis a tipping point beyond which aquaculture expansion could affect the environment more broadly,”McDonald said.