Experimental plots were located in Tasman Bay at four sites (A,B,C and D, 1 ha in size, separated by >2 km). To compare oyster settlement among 3 enhanced habitat shell density treatments, at each site, 9 plots comprising 3 replicate plots of 3 treatments were set up. Treatments comprised: dense shell piled to a height of ~0.3 m above the substratum; scattered shell and non-enhanced seabed as a control. Treatment plots were 4 m in diameter and located 30 m apart within the 1 ha site. Broodstock was added to plots C and D to address this aim (see below for specific aims of the project). Field studies were conducted between October 2004 and May 2009.