Flounder season is back: Know the issues facing this sportfish species — past, present and future

Each year, Texas pauses flounder fishing from November 1 to December 14 to give these unique fish a chance to spawn offshore. When the season reopens on December 15, anglers get excited, which poses a great opportunity to brush up on what makes Southern Flounder so fascinating and what is affecting them today.

With popularity comes challenges, and it’s important to note that this Texas favorite has faced long-term population declines for those aiming to make this catch. Scientists across the coast are working to understand what’s happening, including research supported through Texas Sea Grant. In the following article, we provide background on this species, look back at related research previously supported by Texas Sea Grant and introduce a recent discovery from Dr. Lee Fuiman at the University of Texas Marine Science Institute involving a surprising pigmentation issue in young flounder.

With the proper knowledge, Texans can band together to help keep this popular species thriving in the water, on plates and in sport for generations to come.

Meet the southern flounder – a Texas staple

Southern flounder have long been a staple of coastal life in Texas – popular among recreational anglers, nighttime giggers and seafood lovers alike. They’re the largest flounders found in the Gulf of America and a favorite on dinner tables, whether fried, baked, broiled, or even stuffed with crab.

Part of what makes flounder so unique is their appearance. They start life looking like a typical larval fish, with an eye on each side of the head. As they grow, their right eye migrates to the left side. Their upper side darkens with blotches and spots, while their underside remains pale. This shape and coloring allow them to blend into the seafloor, reducing their visibility to both predators and prey.

In addition to this adaptive biology, flounder are also known to be resilient in nature. They tolerate a wide range of temperatures and salinities and settle in habitats with soft bottoms, jetties, or oyster reefs. Females grow much larger than males – often reaching 25 inches – so most legally harvested flounder are female, a detail that underscores why careful management matters.

Management and migration

The Texas Parks and Wildlife Department (TPWD) has managed Texas flounder populations and the flounder fishery for decades. Fisheries management is the science-based practice of regulating fishing activities to ensure that fisheries resources remain healthy, productive, and sustainable over time. This may involve setting rules that limit how many fish can be caught, which gear types can be used, and when and where fishing is allowed.

Beginning in the 1980s, TPWD implemented major conservation measures, including banning commercial netting for flounder and establishing minimum size limits and daily bag limits for recreational anglers and commercial fishermen. These actions reduced overharvest and helped stabilize and rebuild flounder populations.

The current seasonal closure from November 1 to December 14 is designed to protect flounder during their annual spawning migration, when large numbers of fish move from Texas’ protected bays and estuaries toward offshore spawning grounds. As they make their way to the Gulf via coastal passes, the flounder are especially vulnerable to anglers fishing in these areas. 

Why have populations declined?

Despite management efforts, Southern Flounder populations have been declining throughout the Gulf in recent years. Research points to several interacting factors driving this decline, including increased fishing pressure, water temperature changes and habitat loss, particularly in estuarine environments that are critical for juvenile development. Scientists are also reassessing whether existing seasonal closures still align with the species’ biology, as water temperature changes alter migration timing and environmental cues.

Recognizing the importance of adaptive management as these conditions continue to evolve, researchers are working to improve estimates of total fishing pressure and survival. One notable example is a Texas Sea Grant–funded project led by Dr. Greg Stunz at the Harte Research Institute, which explored the use of social media to better quantify recreational flounder harvest and effort.

Traditional daytime creel surveys often fail to capture the high levels of nighttime gigging—a popular method in which anglers spear flounder after dark—resulting in significant underestimation of total catch. To address this gap, the research team analyzed 2.6 years of photographs from guided nighttime flounder gigging trips posted on Facebook. Their analysis revealed large party sizes, substantial trip-level harvests, and peak fishing activity during summer months, well outside the traditional flounder season.

When nighttime gigging data were combined with existing daytime recreational and commercial harvest estimates, the results nearly doubled the estimated total annual harvest. These findings underscore the magnitude of fishing pressure on Texas’ southern flounder populations and demonstrate the value of nontraditional data sources, such as social media, for monitoring fisheries that are difficult to assess using conventional survey methods.

Emerging issue: malpigmentation in hatchery-reared flounder

One intriguing discovery in flounder science is a pigmentation anomaly affecting hatchery-reared juveniles. Texas Sea Grant spoke with Dr. Lee Fuiman, director of the Fisheries and Mariculture Laboratory at the University of Texas Marine Science Institute, about his findings on this emerging issue.

Dr. Fuiman noted that, while malpigmentation is rarely spotted in wild flounder at this stage, which likely could be attributed to affected juveniles being eaten quickly, it is more noticeable in hatchery-raised fish. Because survival depends on proper camouflage, understanding and reducing malpigmentation is essential for the species’ long-term sustainability.

“Southern flounder are ambush predators that lie motionless on the bottom and wait for shrimp or small fish to approach,” Fuiman explained. “Their prey come close because they can’t see the flounder — the pigmentation on the eyed side blends in with the surroundings. That same camouflage also protects flounder from predators, especially when they are very small. Without proper pigmentation, flounder can’t hide, can’t feed effectively and are unlikely to survive in the wild.”

Malpigmentation appears in two forms: dark patches on the white underside, which mostly affect marketability, and pseudoalbinism – when the normally dark upper side turns white – leaving fish unable to camouflage and making survival unlikely.

In 2023–2024, TPWD staff collaborated with Dr. Fuiman’s team and found malpigmentation rates as high as 28% in some hatchery runs, compared with just 8% in lab settings. Follow-up research showed diet was a major factor: adjusting the TPWD hatchery diet reduced malpigmentation from 28% to about 18%.

Since diet doesn’t explain all cases, Dr. Fuiman notes that researchers are now investigating environmental factors. Gene expression studies have already identified markers that distinguish normal from malpigmented fish before pigmentation appears, and a larger molecular study of over 10,000 genes is underway.

Looking ahead, Dr. Fuiman’s team is exploring whether environmental changes could increase malpigmentation in the wild, potentially raising early-life mortality. Meanwhile, this work has already improved Texas’ hatchery stock enhancement program and is informing similar efforts in North Carolina and Alabama, helping ensure healthier flounder populations for the future.

What comes next?

Researchers like Dr. Fuiman, along with teams studying population trends, are working to understand how all these pieces fit together: physiology, habitat, sea temperature, fishing pressure and more. Their findings will help forecast what flounder populations may look like in the decades ahead.

Flounder play a big role in Texas’ coastal culture, and their future depends on continued research, responsible harvest and informed communities. As anglers head back out onto the water this season, staying aware of the past, present and emerging issues surrounding this species can help ensure that flounder remain a Texas tradition for generations to come.

References

• Stunz, G. W., et al. (2024). Shining Light on Harvest and Effort for the Recreational Flounder Gig Fishery in Texas (2022–2024). Texas Sea Grant and Harte Research Institute.
• Southern Flounder species information and life history — Texas Parks & Wildlife Department. Texas Parks & Wildlife
• Flounder bag and length limits — Texas Parks & Wildlife Department Outdoor Annual (2025–26). Texas Parks & Wildlife

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About Texas Sea Grant

Texas Sea Grant is a unique partnership that unites the resources of the federal government, the State of Texas and universities across the state to create knowledge, tools, products and services that benefit the economy, the environment and the citizens of Texas. It is administered through the National Oceanic and Atmospheric Administration and is one of 34 university-based Sea Grant Programs around the country. Texas Sea Grant is a non-academic research center at Texas A&M University. The program’s mission is to improve the understanding, wise use and stewardship of Texas coastal and marine resources.