Counting fish: Performative data, anglers' knowledge-practices and environmental measurement

This paper examines how environmental resources are measured and quantified as objects of environmental science and management and how lay knowledge-producers participate in this process, alongside the state. Using a case study of recreational angling, I show how fish in English rivers and lakes are counted and anglers act as lay or amateur knowledge-producers in the state's metrological knowledge-practices. As embodied measurement instruments, anglers create data about themselves (as 'effort data') and about fish (as 'catch returns'). These data are combined with other forms of data produced by the Environment Agency in England and Wales and used for fisheries management, thus shaping water bodies and fish ecology. I show how, to support environmental measurement, the state manages not only the environment and fish, but also anglers as lay knowledge-producers, using both regulation and economic incentives; in response, anglers also use data reflexively and strategically. I therefore emphasise the heterogeneous co-productions of environmental measurement as amateur-professional, human-animal and organic-technological, and show how measuring and managing water ecologies also involves measuring and managing humans.

► Recreational anglers' effort data and catch returns input to fisheries management. ► Environmental measurements are co-produced by humans and nonhumans. ► Environmental measurements are co-produced by amateurs and professionals. ► Anglers' embodied performance as measurement instruments is managed by the state.