What does it mean when an entire nation is “performing” sustainability? In the Icelandic fishery, data and information technology (IT) have been framed as solutions to overfishing and natural resource management for over thirty years. During this time, the Icelandic government has implemented a series of highly contested natural resource management schemes aimed to protect and preserve the economically valuable resource, from alternating between restrictions on access to the fishing grounds, capping the allowable fishing amount to restricting and limiting fishing efforts. Throughout these different system implementations, the common thread is a heavy reliance on data and technology as tools to control and manage the fishery sustainably. I argue that framing data as a solution to the issue of sustainability has narrowed our view of the fishery such that both the fish and the people relying on the resource disappear from view, being replaced by data. In this dissertation, I present data from ethnographic research that demonstrate some of the unintended consequences that have unfolded as a result of this focus on data. I examine the datafication from the ground up, focusing on the perspective of fishermen and captains in particular. Starting with the the moment fish is transformed into data on board a freezer trawler in the North Atlantic, I demonstrate how the fish gain a new life as data with a variety of new roles, different meanings and accompanying political agendas. Next, I move on to examine changes in the work practices of captains. Looking at the day-to-day responsibilities of the captain, we see an ever-increasing role of governance and surveillance through IT and data. One unintended consequence of this is that the role of the captain - applied craftsman or a blue collar laborer - has expanded to include more white collar tasks without reaping any of the benefits that would come with such a shift (e.g. increased autonomy, elevation in status). Finally, I examine the historical context of the natural resource management system that has prompted these changes, demonstrating a feedback loop between data and new forms of governance.