Characterisation of fishery selection is key to reducing uncertainty in the assessment and management advice provided for CCAMLR toothfish stocks. Toothfish migrate towards deeper waters as they age and increase in size and, in combination with the practical difficulties associated with deploying fishing gear at increasing depths, there is the potential for a dome shaped selection with age and size to arise. However this type of selection pattern is associated with the estimation of highly uncertain quantities of cryptic biomass. A review of the fishery and tagging data from the Patagonian toothfish (D. eleginoides) in Subarea 48.3 is used to determine whether there is sufficient information to determine the most likely fishery selection profile. A simple metric, the distribution of tag age with depth, is suggested as an indicator that a dome selection pattern is unlikely in the 48.3 fishery.