Bull sharks hunting a fresh feed in the wake of ex-tropical cyclone Oswald are moving in on popular swimming spots along the Queensland and northern New South Wales coasts.

With silt-laden floodwaters flowing down rivers, schools of fish have moved in search of cleaner, nutrient-rich waters.

And the bull sharks have followed.

It’s no new phenomenon, but fishermen in the northern New South Wales coastal towns of Ballina and Byron Bay, including 18-year-old Henry Phillips, have reported catching dozens of bull sharks at Brunswick Heads and in the Richmond River in the past week.