One of the reasons why GMOs have met public resistance in the past is that they are perceived as “unnatural”. The basis for this claim has, in part, to do with crossing species boundaries, which is considered morally objectionable. The emergence of CRISPR is sometimes argued to be an ethical game-changer in this regard since it does not require the insertion of foreign genes. Based on an empirical bioethics study including individual interviews and focus groups with laypeople and other stakeholders, (...) this article analyses the normative role of appeals to naturalness in discussions about the moral acceptability of using CRISPR in salmon farming. It discusses two dimensions of naturalness found in the material– living by species-specific nature and being unaffected by humans– and argues that these dimensions put down criteria for the application of CRISPR that lead to a conflict between our moral duties towards the farmed salmon and those we hold towards the wild salmon as a threatened species. It also points to a paradox which is likely to gain traction with further climate change and biodiversity loss, namely that while nature, understood as that which is unaffected by humans, is presented as an ideal, conserving nature in its pristine state may rely on technology and human intervention. (shrink)