O'Donnell's fishing trips took place in the last two or three years, but before the state banned killing the sharks Jan. 1, the South Florida Sun Sentinel reported.
However, the comedian, talk-show host and mother of four came under fire from marine biologists, diving organizations and environmental groups after fisherman and guide Mark "The Shark" Quartiano recently posted a photo of her on his Web site standing next to a dead hammerhead.
"Right now, sharks are the most endangered animals around," the newspaper quoted Erik Brush, a Sarasota marine conservationist who helped start a campaign against O'Donnell, as saying. "This is basically an endorsement. It sends the message that it's an OK activity. And this is not an activity that we want celebrities endorsing."
Samantha Whitcraft, conservation biologist with the non-profit group Shark Savers, told the Sun Sentinel she contacted O'Donnell through Twitter and offered to take to her to a shark research lab, but never heard back from her.
"To be fair, I think by the time I had reached her she had been unbelievably harassed. I saw her Twitter page and a lot of overly aggressive hazing," Whitcraft said.
The Sun Sentinel said O'Donnell's publicist did not respond to requests for a comment on its story.
But Quartiano defended killing hammerheads, saying commercial fishing fleets kill many more sharks than those who hunt for sport.
"These conservation guys are hitting the wrong target," he said.