Assessments of three replicate populations of blacklip abalone ( Haliotis rubra) were made utilising a range of techniques, enabling critical assumptions to be tested in an empirical manner. Methods included catch-effort (Leslie), change-in-ratio (CIR), mark-recapture (MR) and diver-survey techniques. Population assessments were carried out under the same experimental protocol and within adjacent, closed areas of 5 ha. To establish a Leslie estimate, a 50% stock reduction of each population was carried out using commercial abalone divers. The principal objective was to make a comparative evaluation of methods with respect to their accuracy, precision, robustness and data requirements. A total of 8 tonnes (35729 individuals) of abalone (≥ 10 cm) was harvested. The diver-survey (30 m 2 transect), MR and CIR (using 30 m 2 transect data) methods were given the highest overall rating. In general, the CIR (using timed collection data) did not perform as well as the CIR (using transect data). Leslie estimators were inaccurate and imprecise for two out of the three populations. Furthermore, the correction of unit effort from total dive time into searching and handling time for both the Leslie and timed collection population estimators did not improve the reliability of the estimate. The timed collection diver-surveys, while precise, were highly inaccurate and their use for abundance estimation in abalone is not recommended.