( CNN ) -- They 're friendly , intelligent and playful . So who 'd want to shoot a dolphin ? Conservation experts and federal agents say they 're looking into the violent deaths of several bottlenose dolphins along the northern Gulf Coast this year , including one that was shot and another that was stabbed with a screwdriver . `` I ca n't explain why anyone would shoot a dolphin , '' Jeff Radonski , a Florida-based special agent for the National Oceanic and Atmospheric Administration , told CNN . Radonski said NOAA is investigating four of the six deaths reported since June . Samia Ahmad , a spokeswoman for the Institute for Marine Mammal Studies in Gulfport , Mississippi , said at least six dolphins had died as a result of foul play since January . In one case , a dolphin had its jaw cut off , she said . In September , a dolphin that washed up on Elmer 's Island , Louisiana , had been shot . The bullet that killed it was found in its lung , NOAA reported . In June , a bottlenose was found in Perdido Bay , on the Florida-Alabama state line , with a screwdriver stuck in its head , the agency said . Dolphins are covered by the Marine Mammal Protection Act , a 1972 law that makes killing them punishable by fines of up to $ 20,000 and a year in prison . In at least two previous cases , fishing charter captains have been found guilty of shooting at dolphins that approached their boats or the fish their passengers had hooked , NOAA says . NOAA spokeswoman Allison Garrett told CNN that the most recent prosecution involved a Panama City , Florida , man who was convicted of throwing pipe bombs at dolphins . He was sentenced to two years in prison in 2009 for violating the federal conservation law and for possessing an explosive device as a convicted felon . World 's rarest whale species washes up .
` ` I ca n't explain why anyone would shoot a dolphin , '' a police officer says . At least three dolphin deaths have been reported so far this year . Two earlier deaths involved fishing charter ##s .