SIMS

Grey Nurse Shark
Photo: Rob Harcourt
© Rob Harcourt

In 2003 Harcourt completed a study, in conjunction with NSW Fisheries, of the Grey Nurse shark, which was decimated by spearfishing in the 1960s and is now critically endangered in New South Wales waters. He collected data on the shark's population size, ecology (including birth rates, habitat requirements, life expectancy and maturation) and reported mortality rates, and entered it into a statistical model to come up with worst-, likely- and best-case scenarios.

Disturbingly, the study found that Grey Nurse sharks off the east coast of southern Queensland and New South Wales probably now number fewer than 1000, and will most likely be effectively extinct from the region within 50 years unless immediate action is taken. The research was published in the international scientific journal Biological Conservation and will be used by NSW Fisheries to better manage and protect the species.

"Because they are long-lived, late to mature, have a maximum of only two young every two years, and have specific habitat requirements, they are particularly vulnerable to extinction," says Harcourt. "Their numbers will not recover unless we take serious and immediate action."

Postdoctoral Fellow Dr Adam Stow, who has previously studied the degree of genetic divergence between eastern and west coast Grey Nurse sharks, is presently a chief investigator on a grant titled 'Conservation Genetics of Wobbegong (Orectolobus spp) and Grey Nurse (Carcharias taurus) Sharks in Australia' provided by Sea World Research and Rescue Foundation Incorporated.

With support from other conservation geneticists at Macquarie and at the University of KwaZulu-Natal, Stow is undertaking a genetic comparison of Australian and South African Grey Nurse sharks using state of the art DNA forensic tools to establish whether sharks migrate between the two countries, and whether breeding between these groups could possibly save the shark population off NSW and Queensland. Because grey nurse sharks rarely surface, they are almost impossible to track using satellite tagging technology.

Belgian PhD student at Macquarie, Charlie Huveneers is concurrently studying wobbegong sharks of NSW. Like the Grey Nurse, little is known about the wobbegong other than that their numbers have steadily declined in the past 10 years.

Huveneers is hoping to discover the reason for this decline by undertaking the world's first comprehensive study of the wobbegong shark in collaboration with NSW Fisheries, the commercial fishing industry and recreational divers. His PhD research will assess the impact of inshore fishing on the two species of wobbegong - the spotted and ornate wobbegong - found along the NSW coast.

Huveneers' research has already proven unexpectedly beneficial, with the discovery of a previously unknown dwarf variety of wobbegong in NSW, which has been genetically confirmed as a separate species.