Are Extensive Marine Protected Areas necessary or even desirable?

In recent discussion with regard to the matter of a greatly expanded network of large MPAs right around Australia, Department of Environment and Heritage personnel have claimed that these MPAs are necessary to meet international obligations to which Australia is committed. In order to better understand the specific nature of such obligations Mr Wayne Bayne of the Fishing Party requested from DEH a list of the relevant treaties and conventions. These were supplied and Wayne then requested my comments on them. This Memorandum dated 5 June 2009 is my reply.