Movements of the Southern Rock Lobster Jasus edwardsii in Tasmania, Australia

The magnitude and direction of movements of spiny lobsters Jasus edwardsii (Hutton, 1875) around Tasmania were examined from 39,000 tag- recapture events that occurred between 1973 and 2001. There was no evidence of large-scale, unidirectional migration, as observed elsewhere in the same species. Tag-recaptures indicated high site fidelity with the majority of animals moving no detectable distance after periods of one-two yrs between capture events. Sex, female maturity, and geography influenced the magnitude of lobster movement with significant interaction between these factors. Site had a pronounced influence on the magnitude of movement with consistently greater movement in the north of the state. The lowest magnitude of movement occurred in southern areas, which are known to have highest lobster density. The effect of female maturity on the magnitude of movement was influenced by site, with greater movement by immature females than mature in the northeast, but not the northwest. The direction of movement of animals recaptured on at least five occasions (n = 434) was not significantly unidirectional, although about 20% of these animals exhibited axial bi-directional movement. Significantly unidirectional movement from single recapture events was detected in the majority of areas for males in summer and females in spring, which may be associated with biological events of molting and larval release, respectively.