Nothing creates more confusion and anguish among anglers than the words "Red Tide."
For weeks now, a harmful algae bloom has been lingering 5 to 20 miles offshore between Tarpon Springs and Dixie County. There have been reports of fish kills in deep water, but as of today, there have been no issues reported inshore.
Local fishermen and boaters remember Tampa Bay's last major Red Tide. In 2005-06, water- and tourism-related businesses lost millions as dead fish covered local beaches and shorelines.
"There a lot of misconceptions about Red tide," said Dr. Vince Lovko, manager of Mote Marine Laboratory's Phytoplankton Ecology program. "Perhaps the greatest one is that it is always red."
Lovko said the organism that causes Red Tide, Karenia brevis, sometimes turns the water a rusty red, or it might just be a dark patch on the surface.
Scientists from Mote, the Florida Fish and Wildlife Conservation Commission and the National Oceanic and Atmospheric Administration, are aboard a research vessel in the Gulf of Mexico monitoring the algae bloom that has expanded and shrunk in size several times in recent weeks.
Lovko said anglers always want to know what triggers a Red Tide, but he said there is no simple answer.
"We don't fully understand the role nutrient sources play but there tends to be some common misconceptions about the role human activity plays," he said. "We do know that they usually start offshore and that they have been occurring for a long time, even before the first settlers arrived here."
Lovko said microscopic algal species similar to the plantlike organism that causes Florida Red Tide can be found in all of the world's oceans and many freshwater lakes. At high enough levels, these organisms can turn the water brown, green and even purple.
While researchers have kept good scientific records of Red Tides in recent decades, diaries of the early Spanish explorers contain numerous accounts of fish kills in the Tampa Bay area.
Sometimes a Red Tide can last just a few weeks, then return a month later. Other times, such as 2005-06, the killer bloom can linger for more than a year. Our local variety, K. brevis, likes the offshore habitat, where the salinity is higher, and doesn't live long when it moves up into an estuary such as Tampa Bay.
The most recent report shows a high concentration of Red Tide about 5 to 10 miles off the Central Pinellas coast and moving slowly south. But as Lovko added, "It can move up and down the water column. One day you may see it … the next you don't."
Many Red Tides, including K. brevis, produce toxic chemicals that can affect the nervous system of fish and other organisms. Sometimes, when a Red Tide gets close to shore, wave action can break open the algae which releases the toxins into the air, causing respiratory problems for humans.
Officials say it is still safe to swim, but if you experience eye, nose or throat irritation, get out of the water. And if you see dead fish floating, find another place to swim.
Anglers can eat the fillets of any fish caught during a Red Tide, because the toxins usually accumulate in the fish's internal organs, not the meat. But don't eat anything if it does not look healthy.
The FWC operates a "Fish Kill" hotline. The state agency also has an excellent information page on Red Tide. To learn more, go to myfwc.com. Mote Marine Laboratory is another leader in Red Tide research. Go to mote.org/news/florida-red-tide.