Shellfish aquaculture in Prince Edward Island (PEI) has been impacted with the arrival of four invasive tunicates over the past two decades. Treatment methods have been developed to minimize the impact of these infestations on the shellfish aquaculture industry, with some consideration on associated ecosystems. Tunicates are important fouling organisms that compete with mussels, oysters and associated fauna for space and food. Untreated infestations have led to reduced growth rates and meat yields of farmed shellfish and significant loss in productivity due to fall-off of mussels. The main impact, however, is food depletion and bio-deposition which could lead to some disruption in the ecological function of infested estuaries. Science has played an important role in providing key knowledge and advice to identify management options, particularly relevant to environmental consideration. This knowledge now plays a key consideration in the expansion of the shellfish aquaculture in

PEI and other areas affected by tunicate infestation.