More research is needed to determine full impacts, the following are some important pieces of information found:

Geoduck Growth:•Bivalve filter feeding can improve water quality and slow eutrophication•Increased bio deposition and organic carbon into the sediment increases oxygen demand which can cause anoxic conditions Harvesting:•Harvesting methods are currently low impact and any visible effects on the sediment will return to pre-harvest within a month•Current environmental regulation allows harvest in environmentally designated open areas•Alexandrium cysts (a toxic algae) and other toxins suspended from sediment into the water column by hydraulic harvesting can build up in geoducks and other shellfish and can harm humans if ingested•Geoduck farming aquaculture, while efficient, can be a source of pollution due to the PVC pipes and netting

Effects of Geoduck Harvest on Water QualityJustin Wilson

King County WLRD Science Section

Introduction

Geoducks (a type of shellfish) are an essential part of the lifestyle for some tribal communities and others in the state of WA. Harvesting is a source of commercial income, a delicacy, and a cultural resource. Commercial geoduck harvesting is a relatively new practice, beginning in the 70’s. Harvesting has been refined over time to be efficient and at first glance relatively harmless to the environment. The goal of this project is to survey any potential issues geoduck harvesting may present to water quality.

Study Question and Hypothesis

Does geoduck harvesting have any affect on water quality in the area where the animal is harvested?Methods include a literature survey and 6 interviews of shellfish biologists as well as tribal representatives and outside organizations.

New Questions

Geoduck economy graph-Washington Department of Fish and Wildlifehttps://www.opb.org/news/series/wildlife-detectives/demand-for-super-sized-clams/Survival of Alexandrium Cysts (https://digital.lib.washington.edu/researchworks/handle/1773/33226)Effects of Geoduck Aquaculture on the Environment(https://www.researchgate.net/profile/Lisa_Crosson/publication/237764218_Effects_of_Geoduck_Aquaculture_on_the_Environment_A_Synthesis_of_Current_Knowledge/links/5454049a0cf2cf51647c28c9.pdf)Native Shellfish in Nearshore Ecosystems (http://www.dtic.mil/dtic/tr/fulltext/u2/a477852.pdf) Geoduck harvest effects on water quality (https://protectourshoreline.org/DNR/ComprehensiveLitReview.pdf)

Highlights & Discussion

References

Acknowledgements

Conclusion

• Why isn’t this a question that causes more concern for those directly involved with geoduck harvesting?

• What would it take to truly investigate this question, what type of resources and input would be needed?

• Perhaps this question isn’t the most pressing issue to people, so what would make this question worth investigating?

There isn’t much research currently available on water quality impacts from harvesting. Geoducks aren’t well studied, and a common theme found this is an area worth looking into for the potential impacts on the future. Geoduck aquaculture is a relatively recent commercial industry, but it has a longer tribal harvest history. Improvement of harvesting methods may help further mitigate or prevent entirely any unforeseen effects caused by humans and geoduck harvesting. This project has raised additional questions.

I’d like to acknowledge DDCSP, the Doris Duke Charitable Foundation, The National Fish and Wildlife Foundation, the UW College of the Environment and my fellow DDCSP scholars who have helped me throughout this process and made this summer a very enjoyable and fun experience. Also acknowledging Wendy, Stephanie, Tim, and all the other fantastic King County employees that took us on trips and helped us immensely with our projects to make them what they are today. A special thanks to those I interviewed for their time and sharing their information with me.

General Information

•Geoduck distribution is all over the West Coast •Filtration rates range from 7-20 L/hr but observers have noted estimates closer to the low end

•Geoduck commercial fisheries started in the 70’s and began in the mid 90’s for tribes and is now worth $20M annually

https://www.opb.org/news/series/wildlife-detectives/demand-for-super-sized-clams/

Left: An image of a geoduck farm displaying the pvc pipes and the protective netting on top https://www.nationalfisherman.com/alaska/alaska-group-eyes-mariculture-expansion/

Right: A scuba diver harvesting geoduck http://www.columbian.com/news/2013/dec/26/puget-sound-divers-feeling-pain-of-chinas-shellfis/

Left: A postcard of a child on top of a geoduck https://www.flickr.com/photos/tags/hiatellidae/Right: An exaggerated image of a geoduck being hauled off