The perception of ecological risks (impact and acceptability) associated with introduced marine species (IMS), what demographic variables influence those perceptions, respondent’s knowledge of IMS, and people’s support for controlling introduced marine species impacts on the marine environment was explored at three locations in Western Australia: Ningaloo Reef Marine Park, Rottnest Island Marine Reserve, and Hamelin Bay. Recognition that introduced marine species are an issue at state, national and international levels exists; yet often marine protected area management plans do not reflect this recognition. Therefore, we hypothesise that there is a lack of translation of concern regarding introduced marine species as a risk into tactical objectives within marine protected area management plans. This may be due to low stakeholder perceptions of the risk posed by introduced marine species. Survey respondents had a high level (89%) of self-rated awareness ofintroduced marine species and they also indicated (93%) a willingness to support management interventions to prevent, or control the spread of introduced marine species in Western Australia. Our results also indicate that gender (males) and age (18–45 age group) influenced respondents’ perception of risk (impact) of IMS, yet no examined demographic variables influenced respondents acceptability of risk. Furthermore, knowledge of introduced marine species, education level, and income variables did not influence respondents’ perception of risk (impact or acceptability). Understanding demographic characteristics that influence participants perceptions related to introduced marine species can be useful for targeted, educational initiatives to reduce the likelihood of IMS incursions. This begins to smooth the way for management to proactively develop and implement policies that are necessary to more fully protect the Western Australian marine environment.