The Ninety Mile 2010 survey used a two-phase stratified random sampling design. The survey extent
was defined as the intertidal area of the beach from the headland of Reef Point at Shipwreck Bay
(Ahipara) in the south, to Scott Point in the north (Figure 1). The beach was divided along its length
into four strata (Figure 3) with strata size inversely proportional to assumed density. This split the
beach up into four regions that made sense geographically as well as with the historical toheroa
distribution. Although primarily produced to survey toheroa, the design also suited the estimation of
tuatua abundance