LAUSR

The monitoring of western rock lobster (Panulirus cygnus George, 1962) post larvae (puerulus) has been conducted since 1968 and has proven to be a reliable predictor of recruitment to the fishery. In the late 1980s, the material used to construct the puerulus collectors ceased production and a replacement was sourced. A number of different trials were subsequently initiated to assess the relative catchability of the historical and new collector materials. Due to the different trial designs and their implementation, individual estimates of the relative catchability of the two materials from each trial were not directly comparable and it was uncertain which trial should be used to develop a correction factor. Therefore, we developed an integrated statistical model that utilized data from all the trials in a single assessment, and produced an estimate of the comparison between the two materials. This model had the advantage of being able to produce an average response measure of the difference in catchability between materials with the error associated with both trials incorporated into a single estimate. Outputs of the model indicated that the original material was 31.7% (95% CI = 27.8%–35.6%) more efficient than the replacement material. This estimate was then used to develop a correction factor of 0.759 for the historical puerulus collectors. Correcting historical settlement levels enabled all puerulus data to be incorporated into the current stock assessment model, improving its ability to estimate recruitment and thus its ability to project future catch rates and to make quota setting estimates.