It doesn't seem like the AMSA is a reliable or unbiased source. Here, in an act of charletonism, they attribute all the dollar value of the tourism in the GBR area to the existence of the marine park! On top of that they don't mention the 300 million in compensation money or the ongoing lost economic activity from fishing related business:

http://www.realdirt.com.au/

This week two of the nation’s leading fish scientists, Professor David Booth and Dr Will Figueira, representing the Australian Marine Sciences Association, gave evidence to the NSW Parliament on marine parks…here is an edited extract of their submission.

The costs of implementing marine reserves are often touted as a reason not to implement them. Certainly there are costs however the economic benefits as a result of increased tourism typically far outweigh these. For instance management costs for the Great Barrier Reef Marine Park are on the order of $35 million per year while revenues resulting from the park are approximately $5 billion per year.