Please don't feed the dolphins.

Disregard this warning and you've committed a federal offense that could cost you $20,000 and a year in prison.The ban on feeding dolphins and all other wild marine mammals took effect at midnight Thursday, the National Oceanic and Atmospheric Administration announced.

The government acted in response to fast-growing "dolphin-feeding" cruises in the south Atlantic and Gulf of Mexico, but the ban also protects wild sea lions along the California coast from people food, said William W. Fox Jr., assistant administrator of NOAA's National Marine Fisheries Service.

"We are very concerned that feeding marine mammals in the wild will disrupt their natural eating habits and have severe negative impacts on their populations," Fox said in a statement.

NOAA said wild marine mammals fed by humans can grow dependent on the feedings, can get into the habit of approaching boats and could collide with them or get tangled in fishing gear, or could be given harmful food and foreign objects.

Roddy Moscoso, a spokesman for the fisheries service, said the stiff penalties were the maximum under the Marine Mammal Protection Act for harassment of protected animals, which now has been redefined to include feeding them.

It would be up to judges to make the punishment fit the crime, he said.