Sharks, like many animals, can sense when something is amiss in their home environment: the ocean. So, when a hurricane or tropical storm is brewing, sharks in the area have been reported to flee. Barometric pressure is the pressure of the atmosphere, as measured by a barometer. Barometric pressure drops at the center of a tropical system, and scientists measure it to determine how strong a hurricane could be. He said prior to leaving, they were having great luck finding sharks, but when they returned after the storm cleared, their luck had changed.