Speaking to Al Jazeera, the Indiana University professor, said: "I was surprised. I am a political economist, so I've spent my career at the borders between political science and economics.
"In many parts of the world, indigenous people have communally owned resources for a very, very long time. The community does have ownership, but individual persons do not. Then the community has to agree who has access, who can harvest, how do they harvest, who has responsibilities etc.
"My basic point is: There is no single rule that works well for all resources at all scales.
"What we have found in studying the ways people have governed forest, pastures, irrigations systems, lakes and inshore fisheries is that there is an ingenious array of institutions that work frequently – they are not perfect, nothing is – but many are ingenious in the way that they operate and have done so for centuries.
"When we talk about ocean resources we do not, right now, have governance units large enough to handle ocean resources well, so it is one of the failures on our agenda for future work.
"Inshore fisheries, on the other hand, in some places have been handled very well by local communities, so it is very important that we don't make sweeping claims that locals can 'always', or locals can 'never'. What has been on the agenda for some time has been that locals can never organise themselves, and what we have established is that they can frequently do so - and well."
Ostrom, whose work was partly inspired by Williamson, gathered her most important research in a 1990 book called Governing the Commons: The Evolution for Collective Action.
Williamson, 77, did much of his key work in the 1970s.
He showed how hierarchical organisations could thrive because they are effective at resolving conflicts and, in some ways, were more efficient than market-based systems.
But he also argued that problems could emerge when executive authority was abused, making such systems less productive.
"Over the last three decades, these seminal contributions have advanced economic governance research from the fringe to the forefront of scientific attention," the awarding committee said in a statement.