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Frequently Asked Questions

What is red tide?

Red tide is a naturally-occurring, higher-than-normal concentration of the microscopic algae Karenia brevis (formerly Gymnodinium breve).

This algae produces a toxin (brevetoxin) that affects the central nervous system of fish so that they are paralyzed and cannot breathe. As a result, red tide blooms often result in dead fish washing up on Gulf beaches. When red tide algae reproduce in dense concentrations or "blooms," they are visible as discolored patches of ocean water, often reddish in color.

What causes red tide?

Red tide is a natural phenomenon not caused by human beings. When temperature, salinity, and nutrients reach certain levels, a massive increase in Karenia brevis algae occurs. No one knows the exact combination of factors that causes red tide, but some experts believe high temperatures combined with a lack of wind and rainfall are usually at the root of red tide blooms. There are no known ways that humans can control it, but many scientists around the world are studying red tide at present. It's important to remember that red tide has happened before, and the Texas marine environment has always recovered.

How, when and where do red tide blooms start?

Texas red tides have occurred from August through February. They typically begin in the Gulf of Mexico. Currents and winds then transport blooms toward shore. The blooms mainly come up along Gulf beaches, and less frequently into bays and estuaries.

Where is the red tide on the Texas coast right now?

It's almost impossible to say exactly where the red tide is at any given moment, because blooms constantly expand and contract and move around in response to winds and tides. It's important to realize that red tides are typically isolated patches that don't blanket every stretch of beach. They often concentrate around wind- or tide-protected areas like man-made jetties.

How can I get the latest information on the current red tide?

Red tide updates appear on the Current Status page of the TPWD web site and on the Coastal Fisheries Facebook page. Texas Parks and Wildlife has also set up a menu item on its main toll-free information line to provide regularly updated reports on the current red tide event. Call 1-800-792-1112, press 4 for fishing, then 2 for red tide information.

Should I consider postponing a trip to the coast right now?

Red tide is an isolated, patchy phenomenon that does not blanket every stretch of beach. On any given day, there are generally miles of good beach and clean water for beach-goers and anglers to enjoy. However, we encourage all travelers to heed the advice of the Texas Department of State Health Services, and draw their own conclusions, since different people have different comfort levels with these kinds of situations.

Is it safe to eat fish that I catch in or near the red tide?

It's usually okay to eat fish, crabs and shrimp during a red tide bloom because the toxin is not absorbed into the fleshy tissues of these animals. This advice from the Texas Department of State Health Services is based on the assumption that only the "edible" portions are being consumed (the fillet or muscle). Keep in mind that you should never eat fish found sick or dead, whether or not they are caught during a red tide.

Why doesn't the state post signs on the beach warning the public about red tide?

The eye and throat irritation caused by red tide results from high concentrations of the algae and rough surf. These conditions cause the red tide's irritant to become suspended in the air in the salt spray. There is typically little or no irritation when surf conditions are relatively calm. In most red tides in Texas, these conditions vary a lot within the space of days or even hours. As a result, the same part of the beach may have irritating conditions in the morning and those conditions may be gone by afternoon. On a calm day, even with red tide in the surf zone, many people can enjoy the beach since exposure to the irritant would be limited during those calm conditions. The best advice for beach visitors is that if they feel the effects in one area, leave that area and try another one. Some local authorities will post signs on beaches that they manage. Be aware of all beach warnings when visiting the beach.

Is it safe to eat oysters during a red tide?

Oysters and other shellfish such as clams, mussels, whelks and scallops can accumulate red tide toxins in their tissues. People that eat oysters or other shellfish containing red tide toxins may become seriously ill with neurotoxic shellfish poisoning (NSP). Once a red tide appears to be over, toxins can remain in the oysters for weeks to months. For this reason, the Texas Department of State Health Services (TDSHS) closely monitors oyster growing areas for the presence of red tide and red tide toxins. TDSHS has the authority to close shellfish harvesting areas during and after a red tide. Oysters you buy from a restaurant or certified shellfish dealer should not have red tide toxins in them because of the TDSHS’s monitoring program. There are, however, other risks associated with bacteria and other contaminants in raw oysters. For more information about consuming oysters, consult a physician or health authorities such as TDSHS. To find more information on Vibrio vulnificus, which may be contracted by eating raw oysters, please refer to the TDSHS Vibrio Fact Sheet (PDF).

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Additional Information

The Texas Parks and Wildlife Department and the Texas Department of State Health Services investigate reports of possible red tide along the coast and in the bays.

Three common signs of a red tide bloom are:

From the Centers for Disease Control:
The human health effects associated with eating brevetoxin-tainted shellfish are well documented. However, scientists know little about how other types of environmental exposures to brevetoxin—such as breathing the air near red tides or swimming in red tides—may affect humans. Anecdotal evidence suggests that people who swim among brevetoxins or inhale brevetoxins dispersed in the air may experience irritation of the eyes, nose, and throat, as well as coughing, wheezing, and shortness of breath. Additional evidence suggests that people with existing respiratory illness, such as asthma, may experience these symptoms more severely.

To report sightings of red tide during normal business hours, call your local TPWD office. Outside of normal business hours you may call TPWD’s 24-hour communications center at 512-389-4848.

Current information about shellfish closures can be obtained by contacting the Seafood Safety Division of the Texas Department of State Health Services at 1 (800) 685-0361. The Texas Parks and Wildlife Department and the Texas Department of State Health Services investigate reports of possible red tide along the coast and in the bays.