A GoPro video Michalove posted to YouTube shows the shark swimming around the boat in nearly pitch black waters.
"What are the odds that the largest one I tag has to be in the pitch black of night?" he told the Hilton Head Island Packet. "Visibility was minimal. We just couldn't see the line as we were following the shark."
He said it took hours to reel in the shark and fit it with an acoustic tag.
"She'd go under the boat and we'd lose her for a few minutes," he said. "But the whole process went perfectly. No close calls or mistakes were made."
Michalove said he hopes the video helps raise awareness of shark conservation.
"I hope it gets people more interested and wanting to protect sharks," he told CBS News. "There are commercial boats killing hundreds of sharks a day. I hope this gets the public involved to see they're not just out there eating people; they're extremely important to the ecology."
