Survival of field NZMS population was similar between those re-hydrated in the laboratory and in the field, but was lower than that of the laboratory population (GLM treatment p < 0.01, partial regression coefficient for field population in laboratory vs laboratory population of −2.44 and for field population in field vs laboratory population of −2.43) (Fig. 4). Nearly 50% of snails from the laboratory population survived, contrasting with the 10% survival in the field population. Clay moisture was higher in the field population bioassay than that in the laboratory population (GLM treatment p < 0.01, partial regression coefficient for field populationin laboratory vs laboratory population of 0.83, and for field population in field vs laboratory population of 0.65) (Fig. 5), but in all treatments clay moisture was low (less than 10%). Among the 200 animals used as control, only two died in the lab re-hydration and one in the field re-hydration which means that our experimental layout was suitable for this kind of translocation studies.