Since the late 1980s, Julie's research has been focused on studying human impacts on marine ecosystems and how to reduce the problems these create. For the last eleven years her work has primarily been on the impacts of fishing and how marine protected areas can help rectify the failings of other forms of fishery management. This has included work on extinction risk in the sea and how necessary it is to protect areas of the sea from fishing. She has repeatedly shown that complete protection for some areas of the sea is totally justified on conservation grounds and her work provided the first proof that protection from fishing can increase catches in surrounding fisheries. Over the years her work on the effects recreational scuba diving on coral reefs has moved from firstly playing a major role in getting the issue to be recognised, to then seeing it become addressed throughout the tropics. The majority of Julie's field work has taken place in the Caribbean and Middle East.