THE SOUTHERN FLOUNDER (Paralicthys lethostigma) is an extremely important fish in Texas and along the Gulf Coast. It is revered by a hardcore contingent of flounder specialist anglers, appreciated by the angling masses and renowned for its quality on the dinner table.
And it is a species in trouble.
Since the 1980s, flounder have had many ups and downs with populations growing and shrinking and now reaching a point of great concern for fisheries managers from the East Coast to Austin.
“We’re seeing some disturbing trends in flounder stocks. The catch rates for Southern flounder from our gill net and trawl surveys are at the lowest levels recorded since 1982,” said Lance Robinson, Deputy Director of Coastal Fisheries for the Texas Parks & Wildlife Department (TPWD).
“The recruitment index (obtained from shoreline bag seine surveys) is also at historic lows. We’ve heard reports of pretty decent catches over the last couple of years, but this is not expected to last. The catches we’re seeing now are being driven by a decent recruitment class in 2015.”
Flounder fisheries are extremely complex to manage because of factors that do not apply to other gamefish such as speckled trout and redfish.
• Flounder are not legally recognized as a gamefish whereas redfish and speckled trout are. This means flounder are harvested commercially and can be pursued by means other than hook and line (gigging/bowfishing).
Fisheries managers have to keep an eye on rod and reel fisheries for specks and reds whereas flounder have three separate types of angling pressure: 1) Recreational Rod and Reel 2) Recreational Gigging 3) Commercial Gigging.
• Flounder are a bottom fish, and for years bycatch in shrimping trawls has been an issue. It is still problematic, but there has been a drastic decrease in shrimping pressure. Still, bycatch as juveniles and adults is an issue for flounder. Specks and reds are not immune to shrimping bycatch, but they are not a major incidental catch either.
• Flounder are hard to spawn in captivity. TPWD officials have come light years in the ability to stock flounder, but in comparison to the numbers of redfish and trout that hatchers produce annually, it is a minimal factor.
• Flounder spawn in the Gulf of Mexico. Speckled trout do most of their spawning inshore. Redfish spawn in the nearshore Gulf where the eggs and fry are easily transported by incoming tides into estuarine marsh.
Flounder are different in this regard.
“While they spend most of the year inshore feeding on invertebrates and smaller fish,” said Shane Bonnot, CCA Texas Advocacy Director, “adult southern flounder migrate to offshore waters each year during the late fall and early winter to depths of over 100 feet to spawn. Some flounder have been found at depths greater than 350 feet, releasing on average 45,000 eggs per pound body weight,”
One hundred feet of water can mean 12 miles out of Port Aransas, but in the Sabine area that can be 40 miles offshore. That’s a long trek for tiny flounder to make it back into bays.
“After the eggs are fertilized in the water column, they float to the surface and, dependent on the water temperature, will hatch after an approximate 48-hour incubation period,” Bonnot said.
This is where things get really tricky.
“From work done by the University of Texas Marine Science Institute, they’ve found there is a very narrow temperature range that larval flounder can survive within,” said Lance Robinson.
“The optimal temperature for survival is 18°C. If the temperature rises or falls by more than 2°C in either direction, within the first three weeks of hatching, larvae die. We also know that sex determination is temperature dependent with males being produced in warmer water and females in colder. Looking back over water temperature data collected with every sample we take, beginning in the mid-1970s we’ve been able to document that average water temperatures have increased along the Texas coast by about 2° C.”
Robinson said this issue is not unique to Texas.
“I’ve spoken to state biologists with Louisiana, Mississippi and Alabama who are also reporting significant reductions in this species in their waters. Our suspicion is that these declines are temperature related. As you know, flounder are very temperature dependent,” he said.
Fisheries managers and anglers cannot control the Gulf’s temperatures, but they can regulate various aspects of harvest.
“It is likely that we will never get back to the flounder abundance we observed in the 1980s, but we should do everything within our ability to prevent further declines,” Bonnot said.
“All options should be on the table, and it is time to answer the tough questions many have had for decades. Why have a commercial fishery for a species at the lowest end of its geographical range? What are the effects of the gigging fishery? Why just a 14-inch minimum size limit and why not raise it to 16 or 17 inches to ensure female flounder have two years to contribute to spawning biomass?”
With the current 14-inch minimum size limit, only 50 percent of the fish reach sexual maturity. Most would reach that level by 17 inches.
Other options could possibly include the following:
• Full spring closure to allow flounder to return from the Gulf undisturbed.
• Extension of current fall regulations (October to December?)
• Year-round two flounder bag limit
• Seasonal gigging closure during spring or summer
None of these have been proposed at the time of this writing, but they are the only real options if regulation changes are made.
There is no question that if regulation changes had not been made a decade earlier the fishery would be suffering to a greater extent. Killing more of the flounder that do make it into the bays is not a solution. Fewer flounder spawning means fewer flounder for anglers to catch.
This is an extremely challenging issue with tradition, commerce and science all playing a factor.
Let’s hope in the end, the southern flounder benefits from good decision-making and advocacy for a great species.
The Sea Center Texas hatchery team works toward replenishing the southern flounder population along the Texas coast.
—story by CHESTER MOORE