The China Shellfish ban – arenic levels in geoduck

Dave McBride

In December of 2013 China banned all shellfish exports from the US west coast.  In Poverty Bay, Washington inorganic arsenic and in Ketchikan, Alaska Paralytic  Shellfish Poisoning toxin were found in geoduck.

Inorganic arsenic found naturally in rock, in the air, or areas where arsenic was used in agriculture.  The US doesn’t have an action level for inorganic arsenic however China is concerned about levels of arsenic found in food.

The Asarco smelter facility in Tacoma was thought to be a possible source of arsenic because of its proximity to the Poverty Bay site.

Testing of geoducks showed arsenic is concentrated mostly in the skin.  Wild geoduck tracts  and farm sites were tested for arsenic showed 8 wild sites in WA and 6 sites in AK showed elevated levels of arsenic.

Each harvest area must be tested and pass to be issued an export certificate to China.

Geoduck aquaculture and the environment: Recent findings and future directions

P. Sean McDonald:

Are transient and resident communities affected by geoduck culture?

The study looked at the disturbance caused by planting geoduck and the disturbance caused by the harvest of the geoducks.

Some transient species, (sea stars, crabs, cockles) showed an increase in abundance when culture gear was present while moon snails, flat fish and hermit crabs were more abundant in areas without gear.  Once gear was removed the transient communities returned to pre-gear placement assemblages.

When gear is present the resident polychete species show an increase while other species show no change  Post harvest resident communities showed no consistent patter with most species showing no change or an increase.

Transient data indicate post gear removal decreases transient species/taxa but they do seem to recover relatively quickly.

Ancient Clam Gardens and Deepwater Sand Lance Habitat

Ancient clam gardens and deepwater sand lance habitats are just two of the many varied topics that were interesting at the biennial Salish Sea Ecosystem Conference held in Vancouver British Columbia this October. 

 Researchers fromSimonFraserUniversitylooked at the effectiveness of ancient shellfish gardens created onQuadraIslandinBritish Columbia.  In these gardens, first nations’ peoples cleared rocks and small boulders down to the low ends of beaches to construct a sill.  These cleared areas filled in with smaller sized sediment particles and created areas of higher quality clam habitat. The sill wall also acted to deter some predators and was thought to increase larval retention.  When coupled with the first nations’ husbandry practices of removing predators to increase survival and removing competitors to increase growth they achieved clam aquaculture in a form that is not much different from what is practiced today.

 Another interesting presentation was of a study using acoustic multibeam ecosounder data, seafloor video, and sediment samples to identify and sample subtidal habitat in the San Juan Channel of the Pacific sand lance.  The sand lance is known to utilize near shore sandy substrates for burrowing emerging in daylight hours to forage in open water.  Sandy upper intertidal beaches are used by adults for spawning and egg deposition.  With this work, the natural history of the Pacific sand lance in its subtidal habitat has been greatly expanded.  A predictive model that uses seafloor characteristics of sediment wave fields was developed to locate potential subtidal sand lance habitats.  Densities of sand lance captured in this study were much higher than what has been reported intertidally, averaging 84 fish/m2 rather than only 5 fish/m2.  What I found the most intriguing was the collection of a single sand lance egg found in one of 59 samples.  This could indicate a low density late season subtidal spawning area that could be considered a “critical” habitat or just be an anomaly.

 Overall the conference presented a wide variety of interesting topics and studies about theSalishSea, its inhabitants, and how they interact with each other.  The Salish Sea Ecosystem Conference was an excellent opportunity to hear from and collaborate with researchers, policy makers, and natural resource managers.


Dungeness Crab Fishery Opens

courtesy WDFW

WDFW photo

Early morning on November 20th the Squaxin Island Tribe’s commercial Dungeness crab fishery will open in south Puget Sound. This includes all of the marine waters south of the Tacoma Narrows except for the Nisqually Reach and Balch and Drayton passages. The fishery will be open seven days a week from one hour before sunrise to one hour after sunset and is expected to run through the end of February before crab shell hardness drops off. However, the fishery may be extended beyond February if the crab remain hard as indicated by weekly shell hardness testing.

The Squaxin Island Tribe has not commercially fisher for crab since 2005 and this season the number of Tribal members participating in this fishery is expected to be low. However, there may be areas of high pot densities since each commercially licensed fisher may use up to 50 pots.

Shellfish Surveys on Private Tidelands

The Squaxin Island Tribe’s Shellfish Department conducted shellfish population surveys on 20 parcels in Hammersley Inlet from June 20th to July 20th 2008.   The surveys focused on naturally occurring beds of Manila clams found in an area that was recently upgraded to “Approved” status for the harvest of commercial shellfish by the Washington State Department of Health.  Once that the surveys are completed the Tribe will work with the tideland owners and the commercial shellfish growers that hold harvest leases to write harvest plans for the joint management and harvest from each tideland parcel.