Mussel Watch Pilot Expansion 2012/2013: a study of toxic contaminants in blue mussels (Mytilus trossulus) from Puget Sound Washington, USA

Washington Department of Fish and Wildlife - Puget Sound Ecosystem Monitoring Program's Toxics in Biota staff, together with 38 partner groups and many citizen science volunteers, carried out a study to evaluate the geographic extent and magnitude of nearshore contamination in Puget Sound biota during the late fall and early winter of 2012/13. This study was called the Mussel Watch Pilot Expansion project and was funded by the U.S. Environmental Protection Agency's National Estuary Program. WDFW staff held three workshops during the summer of 2012 to gauge interest and recruit partners and volunteers to help in the field portion of this study. As a result, 12 organizations signed on to sponsor 48 sites, in addition to the 60 original sites, and a number of other groups (citizen science volunteers) signed up to help manage the field work.

During the field portion of this study 9,040 Pacific blue mussels (Mytilus trossulus) harvested from a Penn Cove Shellfish aquaculture facility were placed in predator-exclusion cages at 108 study sites throughout the greater Puget Sound region. The mussels were left to feed for two months (November - January) and only three cages were lost during the study. At the time of mussel cage retrieval, mussel survival ranged from 63 - 97% at all sites. Subsets of mussels from each site have been assessed for fitness (Condition Index) and composites of mussel tissue from each site are being prepared for contaminant analysis.

A study of this magnitude would not have been possible without the assistance of the many volunteers and partners who signed on to help. Much was learned during the field sampling process and we make recommendations for field management of future mussel monitoring studies in Washington State.