Great white sharks are one of the three species tagged using acoustic tags when caught on one of the many (over 300) drumlines along the NSW coast. In the September 2023 issue of Illawarra Flame I provided data on the time of year (for the period June 2022 to May 2023) and time of day that white sharks visit Stanwell Park.
In this article, I analyse more of the data available from the Shark Smart App.
Each shark has its own unique number. During the sampling period, 17 different animals visited Stanwell Park of which 15 visited only once. Shark 1743 visited on four separate occasions in December of 2022 but the frequent visitor award goes to Shark 1043 which visited on five occasions in April/May of this year.
As we know from other studies of tagged white sharks they move around a lot. Prior to being detected at Stanwell Park our visitors were previously detected at Old Bar (adjacent to Taree), Hawks Nest, Birubi (near Nelson Bay), Maroubra, Cronulla, Stanwell Park, Shellharbour, Kiama and Sussex Inlet.
Sharks can easily pass by many stations as the detection zone is only 0.78 square kilometres and the ocean is very much larger!
As mentioned in my first article, a shark can easily visit the beach undetected as the detection zone is 500m around the receiver which is over 900m offshore.
Our visitors were first tagged in a variety of places with a bias towards the North Coast. The beaches included Ballina, Evans Head (several different beaches), Iluka, Yamba, Port Macquarie, Lake Macquarie and Pambula.
The earliest tag date was July 2019 but most of the sharks were tagged in 2021 and 2022. (Battery life may be about 10 years.)
The Shark Smart website does not provide information on how many are tagged each year nor how many have had a second tag inserted (assuming they take a drumline again).
The current program costs nearly $90 million over five years, not all of it on tagging but the ongoing cost of tagging must be significant. Sharks tagged with the acoustic tags tracked by the listening stations do not appear on the Shark Smart website. The ones on the website are all fitted with satellite tags.
