A biologist collecting data in 55 feet of water near the Western Dry Rocks last month was jerked to the surface by a fishermen apparently angry that her dive flag was in his fishing spot, according to law enforcement officials.

That fisherman, 74-year-old Donald A. Bamford of Stock Island, was arrested Wednesday on a misdemeanor battery charge after a monthlong investigation by state and federal law enforcement agencies.

Alison Johnson, a biologist with the Florida Fish and Wildlife Conservation Commission's Marine Research Institute, was collecting data on the mutton snapper spawn on the seafloor just south of the Western Dry Rocks on May 9 when Bamford grabbed her dive flag and used the line to drag her topside in less than a minute, said State Attorney's Office investigator Franklin Cohens.

Johnson told Bamford she needed to decompress, but witnesses said the fisherman began arguing with her about ruining his fishing spot, said Coast Guard Investigative Service Resident in Charge Paul Shultz.

Eventually, Johnson convinced Bamford to release the line so she could dive and decompress, but by that time she was suffering from a severe headache and made her way back to a FWC research boat, where fellow scientists treated her en route to shore, Cohens said.

Johnson was taken to Lower Keys Medical Center, where she was treated and released.

The Coast Guard told the FWC that Johnson was in state waters, which puts the case under the jurisdiction of the State Attorney's Office. FWC officers asked that the National Oceanic and Atmospheric Administration, which oversees the Florida Keys National Marine Sanctuary, become involved because the incident involved a FWC employee, said NOAA Fisheries Special Agent Kenneth Blackburn.

Johnson, who works out of the FWC's Marathon Marine Research Institute office, said she was not authorized to discuss the case.

Bamford, who is charged with misdemeanor battery, was released from the Monroe County Detention Center on Stock Island at 10 p.m. Wednesday after posting $2,000 bail, according to Sheriff's Office records.

Bamford has one other violation, according to Clerk of Court records. He was cited for careless operation of a vessel in April 2011 and paid a fine.

alinhardt@keysnews.com