Detection and control of mud blister worm (Polydora spp.) infestation on commercial oyster farms throughout the Pacific Northwest

The commercial oyster industry, a crucial sector in the Pacific Northwest, is threatened by infestations of parasitic mud worms—polychaetes in the Polydora species. These pests burrow into the shells of bivalves, causing blisters that release undesirable waste and soil into the seafood. Before now, there was no recorded intrusion of any Polydora species in Pacific oysters from Alaska, Washington, or Oregon. However, our recent findings confirm that multiple species of these pestiferous polychaetes are now copious throughout the west coast states (AK, CA, OR, WA), undercutting Pacific oysters—the region's key shellfish—posing a consequential threat to industrial sustainability.

Faced with this challenge, we must discern the affected growing spaces and understand what environmental aspects contribute to such infestations. We must also determine the most effective worm treatments for farms. We are completing an in-depth assessment of the threats Polydora spp. infections impose on oyster farms across the US Pacific Northwest and devising viable tactical responses that enable growers to overcome this impediment while sustaining long-term oyster production.


  1. Map the current distribution of Polydora spp. at commercial oyster farms across the US Pacific Northwest (Alaska, Washington, Oregon, and northern California). 
  2. Identify the environmental factors that predict high infestation rates.
  3. Identify the most effective intervention that growers can use to reduce transmission and mitigate the negative impacts of infection on product value.
  4. Transfer research results and products from Objectives 1–3 to oyster growers and ensure that growers are equipped to use this information to adapt their aquaculture practices.
Wood_photo 1.jpg

Project Summary

Duration: 3 years
Funded Date: 09/01/2019
Funding level: $359,065
Location: Alaska – AK, Oregon - OR, Washington - WA
Species: Oysters
Topics: Polydora

University of Washington
School of Aquatic & Fishery Sciences

Box 355020, Seattle, WA 98195
1122 NE Boat St, Seattle, WA 98105


Grants and Funding