Red Tide on Florida Beaches

Red tide is a condition found in the water that is caused by an overgrowth of a certain type of algae. It frequently causes fish to die and pile up on the beach, and causes humans to experience respiratory irritation and discomfort. It comes and goes. Sometimes we don't have it for several years. Sometimes it tends to linger for months. It is usually somewhat localized, meaning there may be a bad outbreak in Sarasota, while the beaches of Fort Myers are completely unaffected. How does it affect you? Well, sometimes the dead fish can pile up pretty deep on the beach. I don't have to tell you how bad that smells. Also there is a toxin in the air, released by the red tide algae,  that causes mild respiratory irritation, or worse if you are particularly sensitive. If you have asthma or some other respiratory condition, STAY AWAY from the beach during red tide outbreaks. Pets can also be affected and should be kept away from red tide affected water and shoreline. Also, the dead fish on the shoreline create a breeding ground for bacteria. Always wear good shoes when walking on a shoreline with dead fish. Stepping on the fins or skeleton of a rotting fish with your bare feet will cause a very painful injury and possibly a very nasty and dangerous staph infection.

Cause and Effects of Red Tide Outbreaks

Red tide is caused by a huge bloom of tiny, single celled algae called Karenia brevis, They are microscopic plant-like cells called dinoflagellates that produce potent chemical neurotoxins  These toxins kill fish, contaminate shellfish and create severe respiratory irritation to humans near affected waters.  The water can take on a reddish tint, but it is very difficult to see it unless you are up in the air except when the concentration is extremely high.

Useful Resources for Information on Red Tide

To find out if red tide might be affecting a Florida beach you are planning to visit, go to the Mote Marine Laboratory website .

If you are looking for first-hand information about the status of red tide on Sanibel and Captiva, visit the forum at the BestOfSanibelCaptiva web site: 

To check on the conditions at a specific beach, try Mote Laboratory's daily beach report site:


I frequently hear people speculate that red tide is caused or at least aggravated by manmade pollution and alteration of the natural environment and that it occurs much more frequently now than it did in the past. The fact is that we really do not know what causes red tide to occur. I am not sure that it has been occurring more frequently now than in years past. I'm still looking into this.

History of Red Tide Outbreaks on the Florida Gulf Coast

If you visit this page on the Florida Fish & Wildlife Commission site, you can view a chronology of known occurrences of red tide on the Florida Gulf Coast. The first recorded outbreak was in 1844. The fewest episodes in recent decades seemed to occur in the '70's and 'the 80's (not exactly the most pollution-free years). Starting in 2001, we seem to be experiencing red tide every year along some portions of the coast, although the fish kills are not what they were in the past (perhaps because there are less fish now?). Keep in mind that some years ago we did not have the information and communication network set up that we have today. These days if someone smells a dead fish in St. Pete on Sunday morning, the whole world knows about it by noon. So while it appears that red tides are occurring with greater frequency recently, it is possible that this just shows that they are more likely to be reported.

Here is a link to more Florida red tide historical information from the Fish & Wildlife web site:

What we know about red tide:

  1. Red Tide is a naturally occurring algal bloom that is a part of nature in many waters of the world.
  2. Red Tide needs phosphate and nitrogen to bloom.
  3. Phosphates occur naturally on the Gulf Coast of Florida.
  4. Additional phosphates are released into the water as a byproduct of phosphate mining.
  5. Large amounts of nitrogen are released into Gulf waters as runoff from land-based sources (sewage, fertilizer, animal waste, and other sources).
  6. Nitrogen and phosphates being released into the coastal waters cause an increase in algal blooms of all kinds, leading to serious deterioration of coastal water quality.

What scientists haven't "proven" to the satisfaction of the State of Florida and big business:

Pollution as mentioned above causes an increase in intensity and occurrence of the red tide algae along the Gulf Coast.

What scientists are doing:

More studies and research.

What government is doing:

Requesting more research.

What some visitors are doing:

Choosing other vacation destinations.

What smart visitors are doing:

They wait for it to pass, just like we all do. We've had nasty red tides before, and we'll have them again. People still keep coming to Florida. Life goes on. Be thankful if you don't make your living from catching fish.

There is a book called "Fisherfolk of Charlotte Harbor, Florida" by Robert F. Edic. Institute of Archaeology and Paleoenvironmental Studies, Univ of Florida, Gainesville, 1996. ISBN 1-881448-10-X. It is a book of oral histories taken by Mr. Edic of the old-timer fishermen and women of Charlotte Harbor. A portion of the book deals with red tide. It is obvious that the worst red tide any of them remembered was in 1947: 

" 1947 it wiped the grouper out. It just wiped them out, and they are just now [1990] starting to come back..-Tom Parkinson, commercial fisherman and guide 1914 - 1994.

"The fish were that high [knee deep] all along the beaches--on these island beaches--piled up dead." -Bill Hunter, 1907 - ? commercial fisherman, guide, net maker.

"The red tide wiped us out...there were so many dead fish would be running in there [in your boat] and just plowing the fish aside. There were just millions of them. Just as far offshore as you would go, you would be in them." -Bo Smith, 1929 - 1991, fisherman, sport-fishing guide.

Thanks to Robert Edic for compiling and publishing this priceless written work of oral histories.

The fishermen make some other observations about red tide as well. First they point out that as far as they know, red tide has always been around. Some of them heard stories of the red tide as told by their parents. Back then it was often referred to as "poison water." They also mention that it seems to be happening more frequently now than it did in years past. One cannot ignore first hand observations from the people that spend their lives out on the water.

In the guest column in the July 27, 2005 Anna Maria Island Sun, Elizabeth Moss of Anna Maria wrote about the 1947 red tide: "The high tide started bringing in tangled masses of eels and thousands of small dead fish. Not knowing what to think, we neighbors gathered shovels and rakes and dug trenches and raked in the slimy eels and dead fish. ...Every day, more were washed in. I remember the odor of dead fish and the flies." According to Mrs. Moss, there was speculation at that time that the fish may have been killed by some poison gas bombs disposed of in the Gulf by the US Army. This was before Manatee County had any real experience with a major red tide.

I read an open letter to Jeb Bush, Governor of Florida, posted on a red tide oriented website, saying that the letter writer would not be bringing his family back to Florida because their vacation was not as enjoyable due to effects of the red tide. They were not warned or educated about the red tide and its effects. First, this is a completely understandable reaction. Florida does not do a good job of educating its visitors, possibly because of fears about the affects on tourism. So, many people get an unpleasant surprise. I would be ticked off too. But what people need to know is that Florida beaches aren't the only ones affected by red tide. Hawaiian Beaches, California Beaches, Mexico, and the Northeastern US Beaches all suffer periodically from red tide. In fact, some Northeastern US beaches were particularly hard hit this summer [2005]. Red tide happens in many countries around the world.

Copyright: David McRee,