Understanding the drivers and barriers to participation in citizen science initiatives for conservation is important if long-term involvement from volunteers is expected. This study investigates the motivations of individuals from five marine protected areas (MPAs) in the Dutch Caribbean to (not) participate in different initiatives around lionfish. Following an interpretive approach, semi-structured interviews with seventy-eight informants were conducted and analyzed using thematic network analysis. Approximately 60% (n = 48) of informants indicated that they had participated in citizen science initiatives at the outset of the invasion. From this group, almost half said that they still participated in some type of data collection, but only a few did so within a citizen science context. Many informants were initially motivated to participate in lionfish detection and response initiatives due to concern for the environment. Personal meanings attached to both the data collection experiences and to the data influenced informants’ motivations to sustain or cease data collection and/or sharing. In time, the view of lionfish as a threat changed for many informants as this species’ recreational and/or commercial value increased. Enabling and constraining factors for data collection and sharing were identified at the personal, interpersonal, organizational and technical levels. Our findings have implications for the design of future citizen science initiatives focused on invasive species.