This document constitutes a review of the processing applied to the size data submitted to the Secretariat, including the current species-specific measurement types, and provides compelling examples of the major issues encountered with some data sets available in the IOTC database. It illustrates four major cases: data inconsistencies, truncation of size distributions, duplication of size data, and discrepancies in size data between sources. Through these examples, the paper aims to recall the need for each CPC to (i) provide a thorough and up-to-date description of the data collection and curation systems in place and (ii) scrupulously follow IOTC reporting guidelines so as to reduce as much as possible the exclusion of data not compliant with IOTC standards.