Last week, Washington Sea Grant (“WSG”), the research institution based at the University of Washington tasked with funding marine research and coordinating outreach and education related to sustainable use of marine resources, released its final report to the state legislature regarding research conducted on geoduck aquaculture and impacts to the environment. For those of you not familiar with geoduck aquaculture, or geoducks at all, (pronounced gooey-duck), geoducks are large clams that have become a significant part of the aquaculture economy of the Pacific Northwest. Geoduck production in Washington and British Columbia is an $80 million a year industry, and Washington alone produces 1.3 million pounds of geoducks, which represents 90% of global geoduck aquaculture production.
So, these big clams are big business. With that in mind, in 2007, the Washington Legislature passed House Bill 2200, commissioning studies on the possible effects of geoduck aquaculture in Washington, and placing a priority on research associated with the environmental impacts of geoduck aquaculture. The Legislature tasked WSG with a six-year research program, and the report released last week is the final report associated with that work. From a policy standpoint, it is worth noting that this type of legislative-directed partnership with researchers is a great example of how the legislature can drive basic research beneficial to Washington’s economy. The work conducted by Washington Sea Grant will be very useful in permitting new geoduck aquaculture sites–and potentially defrays the high cost of such permitting, allowing smaller growers to enter the market.
As part of its tasks under HB 2200, WSG previously produced a comprehensive literature review on geoduck aquaculture. The just-released report focused on three research studies that came out of data gaps identified as part of that literature review, with WSG focusing on (1) geochemical and ecological impacts of geoduck aquaculture; (2) disease transmission between cultured geoducks and wild geoducks; and (3) resilience of soft-sediment communities after geoduck harvest.
I’ll hit the highlights of this research in a moment, but, to orient you, this research is focused on geoduck farming–which involves placing PVC tubes in soft sediment, placing small geoduck seed within those tubes, and then covering the tubes with netting to prevent access by predators. After a year or two, the tubes are removed, and then, once the geoducks are mature, (5-7 years) the grower uses a water jet to liquify the sediment, allowing the goeducks to float up in the sediment column where they can be harvested. The research by WSG looked at how these activities impact the environment.
What WSG documented was the following:
1) The process of outplanting–i.e., placement of PVC tubes, adding geoduck seed, and covering the tubes with netting to exclude predators–did not impact benthic macro-invertebrates (think bugs living in mud). Placement of geoduck aquaculture gear did significantly alter abundance and composition of transient macrofauna (think fish), but the researchers considered that impact temporary in nature because of the 1-2 year time during which the PVC tubes and netting were present at a grow site. From a geochemical perspective, WSG noted that the cultivation of geoducks leads to low-to-moderate accumulation of inorganic nutrients in porewater of sediment.
2) The harvest process–i.e., the process of using a water jet to liquify sediment–was also studied. What the researchers documented in this phase of the study is that benthic macrofauna composition varies significantly on a seasonal basis, even on small scales, and that geoduck aquaculture sites are also impacted by natural disturbances such as storm events that have made those sites resilient from a benthic community standpoint. As a result of these two factors (seasonal variability and episodic events), the researchers were unable to discern statistically significant impacts to the benthic community associated with geoduck harvesting. From a nutrient perspective, the researchers documented fluxes of inorganic nitrogen and phosphorous associated with harvesting, but those fluxes were low in amount, and insignificant when compared to nutrient inputs from other anthropogenic sources in Puget Sound. As an aside, I do know that shellfish aquaculture–because it involves no addition of nutrients to the water column–is thought to involve the net removal of nutrients, which can be beneficial in areas impacted by anthropogenic nutrient inputs, and I’d bet that net benefit dramatically outweighs the small nutrient fluxes associated with harvesting.
WSG looked at other components of geoduck aquaculture, including eelgrass impacts and disease. With respect to eelgrass recovery after harvest, WSG found that eelgrass started to recover within a year of harvesting, but that it would likely take a number of years for the eelgrass to completely recover. With respect to disease, WSG gathered data on parasite spatial and temporal distribution, which WSG notes will be useful in managing any farmed geoduck disease outbreaks in the future. WSG also identified a number of research priorities that will be addressed in future work.
Overall (and recognizing this post is getting a bit lengthy), for those of you that are involved in shellfish aquaculture, this body of research is significant in terms of being a one-stop reference library. For those of you that aren’t directly involved in shellfish aquaculture, this work is noteworthy because of how it was driven–i.e., by legislative directive and prioritizing–and is a great example of how elected officials can work with private parties and research institutions to direct basic research with real economic benefits. As a lawyer who works on project-permitting in aquatic environments, I can see the immediate value to those that permit geoduck farms. As a scientist, I particularly appreciate academic research that has immediate relevance–and WSG’s work here certainly does that.