For the past 40 years, bycatch has been a significant focus of fisheries science and management, yet bycatch has evaded clear definition persisting as a perennial fisheries concern. This article brings insights from new materialism to examine the ontological politics of bycatch. Building on new materialist approaches to oceans and fisheries, the article contributes to the bycatch debate by putting forth a new framework for understanding bycatch as multiple, enacted through the material-discursive practices of science and policy. Through a survey of policy and scientific documents, the article traces the emergence of “bycatch” as a global fisheries issue. The analysis broadens the orderings and normative understandings about human and nonhuman life inflected by post-humanist and new materialist traditions, as well as fisheries science and policy.