Saltwater Trust Allocation

2007/08 $68,600

Aim

Provide information on the movement and behaviour of tiger sharks off New South Wales.

Background

Tiger sharks have been an important component of the offshore recreational fishery for at least the last two decades. Large specimens (200kg plus) appear to be relatively common off central NSW during summer months as indicated by their relative ease of capture by game fishing vessels targeting sharks. Numbers caught and dietary studies indicate this species is an important reef associated predator/scavenger.

The population size and stock structure of tiger sharks occurring in NSW waters are entirely unknown. While some long distance movements have been recorded from the eastern US and one satellite-tagged tiger shark in northern Queensland, recaptures of tiger sharks tagged off NSW have been insufficient to determine any long term movement patterns. Only 11 tagged tiger sharks have been recaptured on the NSW tagging program, the longest time at liberty for which has been 4 years. That shark, however, only moved an apparent 200km between release and recapture points. Because the sharks appear in and disappear from NSW waters with the seasons, it is highly likely that they do undertake longer movements. Determining the extent of these movements is an important consideration regarding possible population size, and an aspect of tiger shark biology which is ideally suited to study using PSAT tags.

As well as horizontal displacement information, data from PSAT-tagged tiger sharks will provide very detailed information on the vertical movements of the sharks on a daily basis, for many months.