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<\/p>\nOverall, the number of bull sharks in south-east Queensland is booming \u2013 but it\u2019s not entirely clear why. They could be reproducing at a higher rate, or new populations could be migrating here as waters heat up further north.<\/p>\n
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The University of the Sunshine Coast research team surgically implanting tracking devices into a bull shark. The devices have a 10-year battery life, and can be picked up by receivers from up to a kilometre away. Credit: University of the Sunshine Coast<\/p>\n
In the Brisbane River, numbers are difficult to track in real time as there are no receivers, but Holmes is confident bull sharks are extremely common.<\/p>\n
\u201cDefinitely \u2013 colleagues have actively tracked sharks that were swimming underneath people who were water-skiing and doing all the stuff people do on the river,\u201d Holmes said.<\/p>\n
However, in some highly built-up areas \u2013 including the Mooloolah River through Mooloolaba \u2013 populations have completely collapsed. It\u2019s prompted questions about environmental management and the impacts of development.<\/p>\n
\u201cWe suspect that it\u2019s got to do with all of the structural changes that have occurred,\u201d she added.<\/p>\n
\u201cIt\u2019s the only system that doesn\u2019t have a natural mouth, and all the mangroves have been removed. It\u2019s obviously highly residential.\u201d<\/p>\n
The research is ongoing, but Holmes said its findings could have significant impact on conservation efforts.<\/p>\n
\u201cSharks are the most important thing for a healthy ecosystem,\u201d she said.<\/p>\n
\u201cThey sit at the top of the food chain \u2026 as soon as you knock the sharks out, you then see increases in lots of other species that might then prey on your herbivores, which means all of a sudden algal growth goes out of control, which can smother coral.<\/p>\n
\u201cIt\u2019s all based on a balance.\u201d<\/p>\n
And amid an ongoing political debate, does she believe shark nets really protect beach swimmers?<\/p>\n
\u201cThere\u2019s no scientific evidence to suggest that they reduce the likelihood of attacks,\u201d Holmes said.<\/p>\n
\u201cI\u2019m really happy that a couple of days ago it was announced they\u2019ll be giving the Noosa Council, some powers to trial net removal next year when the whales are migrating.<\/p>\n
\u201cWatch this space.\u201d<\/p>\n
The tracking project has been nominated as a finalist in the Noosa Biosphere Awards.<\/p>\n