In this Florida case perhaps they did know:
TAMPA | At first, Roger Young thought he was the victim of a practical joke. A great white shark in the Gulf of Mexico? No way," the Florida Fish and Wildlife Conservation Commission captain recalled.
Over the years, Young has been sent on his share of wild goose chases. "But if we get a tip, we have to check it out, no matter how improbable it may be," he said.
The anonymous call, placed two years ago this month, reported that a white shark, like the villain from the movie "Jaws," had been caught on a grouper longline boat and brought into Madeira Beach.
"The species has been protected since 2004," Young said. "If you catch one, you have to let it go."
If you don't, it can be trouble.