Tracking Flounder

Flounder research has been picking up steam at Texas A&M’s Harte Research Institute in Corpus Christi. In September and October their goal was to insert acoustic tracking devices in 65 flounder, to see where and when they move this autumn. Underwater listening posts in the Aransas area will record their movements, hopefully answering questions on how many of these fish actually leave the bays during winter.

“Each small, black acoustic transmitter was surgically implanted inside the fish,” says Matt Streich, assistant director and senior research scientist at the Institute. “These fish will also carry a small, visible yellow dart tag near the tail. If one is caught, it’s okay to either keep the fish or release it, that’s part of harvest data. If it carries that yellow tag, if you clean the fish, we would like the acoustic transmitter back. Then we can put it in another fish. We’re putting up flyers at some boat ramps, to alert the public.”

The reason? “Flounder are not looking good range-wise, from Texas to North Carolina,” says Streich. “All the state agencies show a decline. It could be a little overfishing, but the range part of it makes it more likely that climate effects are having an impact.”

“They have a temperature related, sex determinant when they’re 1-2 inches long, so there is concern that milder winter temps are causing it. If the water is warmer than 68°F, most flounder are males. Scientists are worried about masculinizing the population. The double whammy is that with the minimum size of 15 inches in Texas, almost all flounder harvested are females. [Male flounder are smaller.] You’re taking out females from the fishery while the climate is mostly creating males, so that’s a double hammer.”

A third, age-old problem was the annual November harvest, when female flounder migrate to the Gulf. They were hit hard, with a daily bag limit of 20 fish as recently as 1995, with people staying out after midnight (two calendar days) so they could each take 40 fish. They were removing females full of eggs that didn’t make it offshore to spawn that winter. I’ve only been on gig boats a few times out of Port O’Connor, but well remember cleaning fish the next morning in chilly weather, when every fish carried eggs.

Modern gig boats can cover miles of shoreline at night with minimal physical effort. That’s a sharp contrast from wading with a lantern the old fashioned way. Billy, who lived in Port O’Connor his entire life, and worked at Clark’s Marina bait store, told me that back in the day, they would drive a skiff to Matagorda Island and wade/tow it back to town, gigging the entire way on foot. They motored across deeper water. He says they often brought in 100 flounder.

Matt Streich continues: “We did a visual survey, looking for flounder from a boat around Packery Channel and Port Aransas during the last two years, to see if the flounder closure was effective. After they extended the harvest closure from November into the first two weeks of December, we wanted to see if that six-week span matched when these fish leave the bays. Although sometimes, water visibility was a problem.

“So, we made some 3D visual prints of flounder, and put those out in a certain area, and sent our people to check that shoreline. To see how many flounder they missed so we could adjust our counts, based on visibility. It looks like during the two years of our study, most of the fish in our counts increased in number until mid-December arrived, and then dropped off. So it looked like the closure was well-timed.

“There was a study in Galveston that showed 30 percent of their flounder didn’t migrate. And lots of gigging went on after Dec. 15. We definitely saw bigger fish (females) after that date.”

“Another project that will start next year is to mark how close these fish are to the inlets during autumn. We’ll be tagging flounder in the Land Cut to see if those fish are less likely to migrate offshore, than the Aransas fish. It’s a long ways from the Land Cut to the Gulf through either Mansfield’s jetties or Packery Channel.”

I inquired about the flounder population offshore, and the day I gigged a sackful from 2-6 pounds during August, at a depth of 96 feet, about 50 miles off Galveston. It was a rare day when the bottom wasn’t covered with a nepheloid layer, which is a fog bank far below the clear water. Just blue water to the bottom that day, and lots of flounder. They were magnified and the biggest, a six-pounder, looked like nine. When I fired the spear “it was just him and me,” as the old-timers used to say. Our struggle was covered up in a blinding cloud of silt.

“In August? That sounds like some flounder move offshore like redfish and never return,” Streich says. “We don’t have good data on that at all. It’s something we definitely need to get a better handle on. We’re putting in a proposal now to put small satellite tags on flounder offshore, hoping to put them on big ones and track them like cobia. Where they go along the continental shelf. Finding them out there in late summer is pretty interesting, it means they stayed out there. We don’t have good flounder genetic data, but maybe there’s a migrating bay population and then an offshore population.”

It sounds like they need to make some summer dives along the coast, spearing flounder around structure and then doing DNA tests, matching them against bay flounder. From what I’ve seen while diving, flounder are found at all offshore structures from 30 to 100 feet, regardless if they’re at oil rigs, sunken boat wrecks or snapper rocks. If divers can capture flounder way out in 150 feet of water, it would be interesting to see if they’re genetically different from shallow bay flounder. That’s a long migration, from the bays to 60-70 miles offshore between Galveston and Sabine Pass.

Perhaps a local spearfishing club will volunteer to gig flounder in the Gulf, and save the fish heads for DNA tests and to recover the ear (growth) stones.

“We’ve been saving fin clips from inshore flounder,” says Streich. “But I’d be interested in getting samples from offshore flounder, whether caught on hook and line or speared underwater. In case there is a difference between inshore and offshore flounder. Anything from 60-foot depths, out to deeper water. Our dive safety officer probably knows of a scuba club around Corpus, who might be interested.”

There are few production platforms still out there compared with a few years ago. Divers might have to dive a wreck or natural rock, hoping for clear bottom visibility, and prowl the sand around it watching for these fish. Interested divers should contact Streich beforehand, for instructions.

“If flounder in depths of 100 feet or more are related or unrelated to bay flounder, that alone would be interesting to know,” Streich says. “Be sure to record the depth and distance offshore these fish were taken from. With head samples we could age the fish. It would be interesting to know if flounder offshore average 3-5 years old, compared to mostly 0-2 years old in the bays. Measuring their length would be important information, too.”