MANATEE -- Officials were cleaning-up a fish kill at Anna Maria Island on Tuesday morning, but its source had not been pinpointed.

Although workers were in the process of cleaning up dead fish at the north end of Coquina Beach, the situation was "nothing major," said Capt. Joe Westerman, of the Manatee County Marine Rescue division.

Fish that had washed up were all mullet, which would suggest that a fisherman had thrown "undesirables" into the water, Westerman said.

His view was seconded by Carmine DeMilio, Manatee County parks operations manager, in an e-mail message to county staff members Tuesday morning.

"There are no reports of red tide at this time," DeMilio wrote.

Officials also had followed up with Mote Marine Laboratory in Sarasota, where no one had reported or confirmed red tide in Manatee County, he wrote.

Workers did find a number of dead mullet in the area of 66th Street, however.

"I would have to believe, with all of the mullet fisherman, that this was an incident of unwanted mullet fish," DeMilio wrote. "Other than this reporting, the beaches are clean at this time."

A map accompanying DeMilio's e-mail showed the presence of red tide off Charlotte County, but none in the Manatee County area.

Red tide blooms result when the water temperature and salinity reach a certain point. In higher concentrations, it can cause respiratory distress.

Sara Kennedy, Herald reporter, can be reached at 941-745-7031. Follow her on Twitter