The increase from the Animal Legal Defense Fund brings the total reward to $8,000.
FOX35 Orlando reported Thursday that other individuals had announced rewards related to the incident.
The outlet reported that the nonprofit Center for Biological Diversity is offering its own $5,000 reward and Florida native and Marvel’s “Guardians of the Galaxy” star Dave Bautista is offering a $20,000 reward.
The manatee was first spotted in Citrus County’s Homosassa River north of Tampa.
While authorities told Fox News in January that the manatee did not appear to be seriously injured, nonprofit wildlife group Save the Manatee Club said the act “may have caused the manatee discomfort or pain.”
Boat captain Hailey Warrington — who shared video footage of the manatee — told WTVT that it “did seem that the animal was very upset.”
Harassing a manatee, a federal crime, is punishable by a $50,000 fine and up to one year in prison.
Manatees have been protected under the Endangered Species Act for almost 60 years.
Images of the manatee sparked a federal investigation by the U.S. Fish and Wildlife Service.
Anyone with information is instructed to call the Florida Fish and Wildlife Conservation hotline at 888-404-3922.
Manatees are known for flocking to Florida’s west coast at the beginning of the year, though most do not travel in large groups.
Notably, this year researchers report manatees are dying at an alarming rate.
TCPalm reported earlier this month that more Florida manatees have died in the first three months of 2021 than in all of 2020, most of them in Brevard County.
Fox News’ Bradford Betz and James Rogers contributed to this report.