Sharks decline off Queensland’s coast in beach nets

Scalloped hammerhead entangled in a Queensland shark control net at Magnetic Island, Townsville.  Nicole McLachlan

There has been a striking decline in the number of large sharks caught in beach nets off Queensland’s coast over the past 50 years, suggesting that populations have declined dramatically. Catch numbers of large apex sharks (hammerheads, tigers and white sharks) declined by 74-92%, and the chance of catching no sharks at any given beach per year has increased by as much as seven-fold.

Coinciding with ongoing declines in numbers of sharks in nets and drum lines, the probability of recording mature male and females has declined over the past two decades.

This contradicts media statements about booming shark numbers.

European settlers in the late 18th and early 19th centuries described Australian coastlines as being “chock-full of sharks. With the rise of Australian beach and surf culture, and the growing population density in coastal communities in the mid-20th century, increasing numbers of unprovoked fatal encounters with sharks occurred along the Queensland and New South Wales coastlines.

Yet despite this long history of shark exploitation, the historical baseline populations of sharks off Australia’s east coast were largely unknown.

Records of shark catches dating back as far as the 1960s provide a unique window into the past on Queensland beaches.

The data indicates that two hammerhead species – the scalloped and great hammerheads, both of which are listed as globally endangered – have declined by as much as 92% in Queensland over the past half century.

Similarly, the once-abundant white sharks have also shown no sign of recovery, despite a complete ban on commercial and recreational fishing in Queensland, implemented more than two decades ago.

Records from fifty years ago indicate that present day numbers are a fraction of what they once were.

Our results indicate that large shark species are becoming increasingly rare along Australia’s coastline. Source  George Roff, The Conversation

Drone will spot sharks at Australian beaches

Seeking a cost-effective way to monitor beach safety over large areas, researchers have developed a system called SharkSpotter. It combines artificial intelligence (AI), computing power, and drone technology to identify and alert lifesavers to sharks near swimmers.

Once valid objects are detected, they are put into one of 16 categories: shark, whale, dolphin, rays, different types of boats, surfers, and swimmers.

If a shark is detected, SharkSpotter provides both a visual indication on the computer screen and an audible alert to the operator. The operator verifies the alert and sends text messages from the SharkSpotter system to the Surf Life Savers for further action.