Guide

Shellfish: harvest areas, red tide and oyster season

Checked September 28, 2026 against the Texas Department of State Health Services: its Shellfish Harvest Area Status and Maps page, its status table of September 23, 2026, its twelve classification maps, and its pages on harmful algal blooms, the risks of eating shellfish and Vibrio vulnificus; and against Texas Parks and Wildlife’s recreational oyster regulations and red tide pages.

The shellfish tile shows what the Texas Department of State Health Services (DSHS) publishes: a dated table of which shellfish harvest areas on the Texas coast are open and which are closed, and why. DSHS numbers the areas TX 1 to TX 34 and draws them on twelve maps, one for each bay system. This page says which areas are your town’s, what the words mean, and what the table does not decide.

What the tile shows

DSHS’s status page links one PDF at a time, titled “Status of Shellfish Harvesting Areas on” a date. The tile reads that table. It has one row for each harvest area, with three things in it:

• Public Harvest Area Status: Open or Closed. This is the one the tile gives as your town’s answer.
• Private Oyster Area Status: the status of private oyster leases in that area, or n/a where there are none. The tile lists it in the full list of areas but does not use it as the town’s answer. A lease is not open water: Texas Parks and Wildlife says oysters “may only be taken from marked private leases with permission of the lessee.”
• Reason for Status, in DSHS’s words. On the table dated September 23, 2026, every public area was closed, and the reasons given were “Elevated Karenia Counts” and “Precautionary Karenia Closure”: red tide. Leases in TX 29, TX 30 and TX 32 were open that day while the public areas around them were closed.

For each town, the tile takes the harvest areas in that town’s bay system and shows their public status:

• OPEN: every one of those areas is open on the table.
• PARTLY OPEN: some are open and some are closed. The line under it names which.
• CLOSED: every one of those areas is closed, or the town’s water has no harvest area at all (see below).
• CHECK: DSHS’s table does not list any of the town’s areas that day. The tile does not guess.

Each area is listed with its number, its status and DSHS’s reason. Under that, one tap opens every harvest area on the coast. The date on the tile is the date on DSHS’s table, not the day you are reading it.

The status covers all molluscan shellfish, not oysters alone. DSHS says: “Molluscan shellfish are defined as oysters, clams, and mussels.”

How DSHS divides the coast

DSHS publishes a classification map for each of twelve bay systems. The current maps are dated November 1, 2025, and the Lower Laguna Madre map December 1, 2025, all under order number MR-1941. Each map names the harvest areas on it, and whether each is Approved or Conditionally Approved. The numbers skip: there is no TX 10, 17, 22, 23, 28 or 31 on the maps or the table.

The tile gives each town the bay system its water is in. Galveston, Port O’Connor and Port Isabel sit between two systems and read both.

Water with no harvest area

Sabine Lake, the Freeport Area and South Bay each have a map but no TX area on it. Baffin Bay and the upper Laguna Madre have no map of their own and no TX area. For the towns on that water, the tile says CLOSED and says why, because every map carries the same rule. In the words of the Freeport Area and Lower Laguna Madre maps: “All areas not specifically designated as Restricted and Approved are classified as Prohibited and are closed to the harvesting of molluscan shellfish.” The other maps word it slightly differently, and the status page puts it for the whole state: all coastal and inland waters not specifically designated Approved, Conditionally Approved, Prohibited or Restricted are classified as Prohibited. “Those are closed to molluscan shellfish harvesting.”

The maps also name some of this water directly. The Sabine Lake map says Sabine Lake and its tributaries “are closed to the harvesting of molluscan shellfish,” and that Keith Lake is closed too. The South Bay map lists “All of South Bay” as Restricted. The Corpus Christi and Nueces Bays map lists the Laguna Madre south of a line from Demit Point to Padre Island as Restricted, and the Lower Laguna Madre map lists “All areas of the Laguna Madre north of the Port Mansfield Channel” as Restricted. None of it is open to harvest.

What the four classifications mean

DSHS classifies all shellfish water as Approved, Conditionally Approved, Restricted or Prohibited. These are fixed on the maps. Open and closed are the day-to-day status of the Approved and Conditionally Approved areas.

DSHS says restricted and prohibited areas “are classified based on levels of fecal pollution, human pathogens, or contaminants.” The maps also mark smaller prohibited and restricted areas inside the bays, such as residential subdivision channels and harbours, and the water within 50 yards of recreational cabins and houseboats. An area that is open on the table does not open those.

Why an area closes

DSHS says it can change the status of harvest areas “at any time,” and lists high rainfall and runoff, flooding, hurricanes and other extreme weather, major spills, harmful algal blooms, and the failure or poor operation of wastewater treatment facilities. It may also close areas “due to shellfish resource concerns or enforcement issues.”

Red tide

Red tide on this coast is a bloom of Karenia brevis, a microscopic alga. DSHS says it is the one that usually makes the red tides in the Gulf, and that it produces toxins called brevetoxins, which give people neurotoxic shellfish poisoning (NSP) if they eat molluscan shellfish (oysters, clams and mussels) that fed on it. “Karenia” in the reason column of DSHS’s table means this.

• You cannot tell by looking. DSHS says oysters, clams and mussels “may appear perfectly healthy” while carrying the toxin, and that shellfish can become toxic when K. brevis is at lower concentrations than the ones that discolour the water.
• It lasts after the bloom. DSHS says the toxin “is only slowly cleared from shellfish after the red tide disappears,” so shellfish caught “during (or even months after) a red tide” can cause NSP. Texas Parks and Wildlife says toxins can remain in oysters “for weeks to months” once a red tide appears to be over. That is why an area can stay closed after the water looks clear.
• Cooking does not destroy it. DSHS calls the brevetoxins “heat-stable” and says cooking will not eliminate the toxin.
• DSHS closes the bays. In its words: “We would close harvesting to any Texas bays with K. brevis bloom.”

DSHS says NSP symptoms usually start within three hours of eating contaminated shellfish, and anywhere from 15 minutes to 18 hours. The first complaints are typically abdominal pain, nausea, vomiting and diarrhoea, with tingling that starts around the mouth and spreads. DSHS calls NSP a relatively mild illness that usually passes in less than 24 hours, and says there is no specific antitoxin.

DSHS says fish, shrimp and crabs do not concentrate the toxin and are safe to eat “if they are caught alive and acting normal,” but never anything that washed ashore sick or dead or was found floating. Shellfish sold legally in markets and restaurants “also should be safe to eat,” because they come from areas the bloom did not affect.

Texas Parks and Wildlife and DSHS both investigate reports of possible red tide. To report one, Texas Parks and Wildlife asks you to call your local office in business hours, or its 24-hour communications center at 512-389-4848.

Raw oysters and Vibrio

An open area is not a promise about bacteria. DSHS says Vibrio vulnificus lives naturally in marine and estuarine water and can infect shellfish, “especially oysters.” It is caught by eating raw, undercooked or contaminated shellfish, or through a wound exposed to sea, bay or brackish water. DSHS says people with underlying medical conditions, “especially liver disease,” may be at increased risk of infection and serious complications, and that the risk is higher in the warmer months. Texas Parks and Wildlife’s red tide FAQ says the same: oysters from a restaurant or certified dealer should be free of red tide toxins, but there are “other risks associated with bacteria and other contaminants in raw oysters.”

DSHS advises against handling raw seafood with an open wound, and says to wear gloves when you do handle it.

Oyster season is a separate question

DSHS decides whether water is safe to harvest. Texas Parks and Wildlife sets the recreational oyster rules: DSHS’s own page says TPWD is responsible for them, “e.g., seasons and length and possession limits.” Out of season, oysters may not be taken even from an open area, and an open season does not open a closed one. The tile shows DSHS’s answer only.

Texas Parks and Wildlife’s recreational oyster regulations set the season, the size, the limit and the gear, and say oysters “may be taken only from waters approved by the Texas Department of State Health Services.” They also close some minor bays to oyster harvest whatever DSHS says of them, and a strip along the shoreline of approved areas. This page does not repeat the numbers, because they are Texas Parks and Wildlife’s to change.

Read its page before you go.

Before you harvest

• Check the table on the day. Read the date on the tile. DSHS says the status of harvest areas may change every day. For the latest, DSHS’s 24-hour, in-state only, toll-free number is 1-800-685-0361. Its Seafood and Aquatic Life Group is on 512-834-6757.
• Carry the map. DSHS says you should have a current classification map before harvesting, to find the approved and conditionally approved areas. The maps are on its status page, and its Texas Shellfish Harvest Area Viewer shows the harvest areas, their boundary markers and the private oyster leases.
• Know which area you are in. The areas are bounded by shellfish markers, channel markers and points of land described on the maps. Water outside a TX area is prohibited.
• Check the season and the rules with Texas Parks and Wildlife.
• Do not rely on cooking to make shellfish from a closed area safe.

Sources

• Texas Department of State Health Services, Shellfish Harvest Area Status and Maps — the status table and its PDF, the reasons DSHS changes an area’s status, TPWD’s responsibility for seasons and limits, the rule that shellfish come only from approved or conditionally approved areas, the statewide prohibited rule, the twelve maps, the Harvest Area Viewer, and the 24-hour number
• DSHS, Status of Shellfish Harvesting Areas on September 23, 2026 — the table the tile reads: public and private status and the reason for TX 1 to TX 34
• DSHS, Classification of Shellfish Harvesting Areas of Galveston Bay — TX 1 to TX 8, the definitions of Restricted and Conditionally Approved, the smaller prohibited areas, and the 1-800 number
• DSHS, Classification of Shellfish Harvesting Areas of the Freeport Area — the prohibited rule quoted above, on a map with no harvest area
• DSHS, Classification of Shellfish Harvesting Areas of the Lower Laguna Madre — TX 34, the same rule, and the Laguna Madre north of the Port Mansfield Channel as Restricted
• DSHS, Classification of Shellfish Harvesting Areas of Corpus Christi and Nueces Bays — TX 33 and the Restricted part of the upper Laguna Madre
• DSHS, Risks of Eating Shellfish — oysters, clams and mussels; the four classifications; why areas open and close; carrying a current map
• DSHS, Harmful Algal Blooms — Karenia brevis, neurotoxic shellfish poisoning and its symptoms, why cooking does not help, how long the toxin lasts, and which seafood is safe during a bloom
• DSHS, Vibrio vulnificus — how it is caught, who is most at risk, the warmer months, and handling raw seafood
• Texas Parks and Wildlife, Recreational Oyster Regulations — season, size, limit, gear, leases, closed minor bays, and harvest only from DSHS-approved waters
• Texas Parks and Wildlife, Red Tide FAQ — eating oysters during a red tide, how long toxins stay, raw oysters, and reporting a red tide