Red Tide Information

Source: Florida Fish and Wildlife Conservation Commission

What is a Florida red tide?

A red tide is a higher-than-normal concentration of a microscopic alga (plant-like organisms). In Florida, the species that causes most red tides is Karenia brevis (K. brevis). This organism produces a toxin that can affect the central nervous system of fish. At high concentrations (called a bloom), the organisms may discolor the water a red or brown hue. The water can even remain its normal color during a bloom.

Is red tide a new phenomenon?
No. Red tides were documented in the southern Gulf of Mexico as far back as the 1700s and along Florida's Gulf coast in the 1840s.

Can red tides be predicted?
The occurrence of a red tide cannot be predicted, scientists can provide a 3.5 day forecast of where a bloom will move using wind and water current data. The effects of a red tide (e.g., dead fish and respiratory irritation in people) depend on the movement and concentration of the red tide microorganism at a given time. The effects also depend on wind speed and direction. It is important to realize that many people still enjoy the beaches during red tides. Respiratory irritation and dead fish are not always present.

Do red tides occur anywhere else?
Yes, many algae species cause red tides all over the world. Yet, the organism that causes Florida's red tide, K. brevis, is found almost exclusively in the Gulf of Mexico from Mexico to Florida. Florida red tides can be transported around the Gulf of Mexico as coastal waters move with winds and currents. Some red tides have even been carried by the Gulf Stream current into the Atlantic Ocean as far north as Delaware.

How is red tide related to respiratory irritation?
Some people may experience respiratory irritation (coughing, sneezing, and tearing) when the red tide organism is present along a coast and winds blow aerosolized toxins onshore. People with severe or chronic respiratory conditions (such as emphysema or asthma) are advised to avoid red tide areas. Generally, symptoms are temporary and disappear within hours.

How can I find out about current red tide conditions?
Mote’s Beach Conditions Reporting System provides beach conditions reports from select beaches in the Southwest coast of Florida and the Florida Panhandle. The Florida Fish and Wildlife Conservation Commission (FWC) reports red tide concentration levels throughout Florida here.

Is swimming okay?
Yes, for most people. However, in some people, red tide can cause skin irritation and burning eyes. Use common sense – if you are particularly susceptible to irritation from plant products, avoid red tide water. If you experience irritation, get out thoroughly wash off. Do not swim among dead fish because they can be associated with harmful bacteria.

What are some hints for visiting beaches during Florida red tides?

Check Mote's Beach Conditions Reporting for conditions at the beach you plan to visit. If you experience respiratory irritation, wear a mask, such as a painter’s mask, that covers the nose and mouth to filter out marine aerosol particles that contain the red tide toxins. If you are asthmatic or have chronic lung disease, be vigilant about taking your prescribed medicines daily. The state health department recommends that people with such diseases avoid beaches that are being affected by red tides. Always seek medical care if your symptoms worsen. For your home or motel room, keep your windows closed, the A/C on and check/change the unit's filter.

Is it okay to eat shellfish at a restaurant or purchase shellfish from a seafood market during a red tide? (Also known as commercially caught or store bought)
Yes. Store-bought and restaurant-served shellfish are safe to eat during a bloom because the shellfish industry is closely monitored by state agencies for shellfish safety. Commercially available shellfish are often not locally harvested and, if harvested locally, are tested for red tide toxins before they are sold. The Florida Department of Agriculture and Consumer Services closes shellfish harvest areas affected by Florida red tide.

Is it okay to eat recreationally harvested shellfish during a red tide?
No, recreational harvesting of bivalve mollusks such as hard clams, oysters and mussels from conditionally approved or approved shellfish harvesting areas is banned during red tide closures. These organisms should not be harvested and eaten. To determine whether or not harvesting of shellfish is permitted in an area, refer to the Florida Department of Agriculture and Consumer Services.

Is it okay to eat fish, crabs or shrimp during a red tide?
Yes, fish and shrimp can be eaten during a red tide because the toxin is not absorbed in the edible tissues of these animals. You can also eat crab but not the Tomalley. However, if a red tide is in the area, eating distressed or dead animals is discouraged because the reason for the animal’s strange behavior or death cannot be absolutely known. It could be something unrelated to red tide.

Is it okay to eat scallops during a red tide?
Yes, you can eat scallops during open harvest season as long as you only eat the muscle of the scallop. Do not eat whole animals.

Does cooking or freezing destroy the Florida red tide toxin?
No, cooking or freezing does not destroy the Florida red tide toxins.

Where can I get more health and safety information?