The risks of shell‐boring polychaetes to shellfish aquaculture in Washington, USA: A mini‐review to inform mitigation actions

In 2017, Polydora websteri, a shell-boring spionid polychaete worm and cosmopolitan invader, was identified for the first time in Washington State. Shell-boring Polydora spp. and related shell-boring spionid polychaetes (e.g., Dipolydora spp., Boccardia spp.), colloquially known as mud worms or mud blister worms, live in burrows within the shells of calcareous marine invertebrates, reducing the host's shell integrity, growth, survivorship and market value. Mud worms have a long history of impacting shellfish aquaculture industries worldwide by devaluing products destined for the half-shell market and requiring burdensome treatments and interventions to manage against infestation. Here, we explore the risks of mud worms to the historically unaffected aquaculture industry in Washington State. This mini-review is intended to inform shellfish stakeholders by synthesizing the information needed for immediate action in Washington State. We review the recent documentation of Polydora spp. in Washington State, discuss their history as pest species globally, summarize mud worm life history, and discuss effective control strategies developed in other infested regions. Finally, we review existing regulations that could be leveraged by stakeholders to avoid introduction of mud worms into uninfested areas of Washington State.