There has been serious concern over the status of the school shark fishery for many years, and it has been the subject of numerous stock assessments (Punt & Walker 1998). It is a well researched species: Olsen (1954) showed that school shark can make extensive migrations, and that females moved to pupping grounds in the south-east of Australia to give birth. However, despite their apparent ability to move freely through the fishery, there are regional differences in size, age and reproductive condition, together with different catch-rate trends in different regions of the fishery. Originally stock assessment models were based on the assumption of a single freely-mixing stock, in light of the ability of the species to move long distances. However, Prince (1992) argued that the biological and catch data was incompatible with the assumption of a single stock, and was instrumental in having spatial structure in the fishery taken into account. Punt et al. (2000) developed a model that takes account of the spatial structure of the population, allows for multiple stocks and which uses catch-rate data and information from tagging studies to derive values for the parameters of the model.

In this study it was the longitudinal movements of the fish that were of greatest interest, and although daily longitude estimates from the archival tags were highly variable, weekly median estimates appeared reliable. Latitude estimates were based on bathymetry except around Tasmania where none were possible. One fish appeared to move to New Zealand, but the clock in the archival tag was found to be seriously defective when tested upon its return. Although conventional tagging shows movements of school shark between Australia and New Zealand, we conclude that there was no evidence of any movement of archival-tagged fish further east than 149–150° E. No school shark migrated across the entire range of the Australian fishery in the time they were at liberty (<1.5 y), and there was limited mixing between the eastern and western regions of the fishery in this time frame. The restricted movement shown by the archival-tagged sharks provides additional support for the move to spatially-structured stock assessments. Although these results seemed at odds with the impression of wide-ranging movements shown by earlier conventional tagging, re-analysis of tag returns from the 1947–56 tagging program (Olsen 1954) provided support for restricted longitudinal movements. For school sharks ≥ 95 cm total length at release tagged in Victoria and Tasmania, the percentage recaptured in South Australia did not peak until after 4–6 y at liberty for females (~70%) and 12–14 y for males (~40%). These results however depend upon the relative fishing effort in these two areas at the time.