May 2006

Stocking Up

Hatchery-raised fish keep rods bowed all over Texas.

By Larry D. Hodge

Around April 15 every year, dozens of Texas Parks and Wildlife Department Inland Fisheries biologists and technicians gather beside the Trinity River at the foot of Lake Livingston Dam to do a little fishing.

Actually, they do a lot of fishing — electrofishing for striped bass to be used for spawning fry for stocking into reservoirs across Texas. Plunging into the raging waters of the tailrace, biologists use long-handled nets to scoop up trophy-sized fish as they float to the surface, temporarily stunned by electricity. In mid-April the big females bulge with up to a million eggs each, and the males are full of milt.

Biologists examine a sample of eggs from each female collected and estimate when the eggs will be mature. Fish with eggs that will mature within 24 hours or so are tagged, numbered and loaded into fish trailers bound for the A. E. Wood, Possum Kingdom and Dundee fish hatcheries.

At the hatcheries, biologists and technicians work around the clock until all the fish are spawned. They check the fish hourly and strip eggs ready for spawning into a bucket, at the same time adding milt from a male and stirring the mixture with a turkey feather, which helps prevent the eggs from getting damaged. Fertilized eggs are enumerated and placed into hatching jars, where they hatch about 48 hours later. The fry are raised to fingerling size — about 1.5 inches long — in hatchery ponds before being stocked into lakes across the state. In 2005 TPWD stocked about 7.2 million striped bass and hybrid striped bass (palmetto bass, the result of crossing a male white bass with a female striped bass).

The striped bass stocking program illustrates just one of the reasons TPWD stocks fish: to increase the diversity of species found in a particular body of water. Stocking is also used to (1) start populations in new or renovated waters, (2) supplement populations with insufficient natural reproduction, (3) restore populations reduced by catastrophe, (4) provide catchable-size fish in community fishing lakes, (5) enhance the genetic makeup of a population, and (6) take advantage of improved habitat resulting from increased water levels in reservoirs. In all, TPWD stocks about 21 million fish of various species into fresh water each year.

When a truckload of fish hits the water, that’s merely the last step in a long, carefully planned process. District biologists use electrofishing, gill netting and creel surveys to assess the status and use of fish populations in reservoirs they manage. If a reservoir’s fish population (and, ultimately, fishing) can be improved by stocking, they then prepare stocking proposals requesting specific numbers of particular species for that reservoir. A review process at regional and state levels sets a stocking priority for each reservoir, since hatcheries are usually unable to supply enough fish to meet all the requests.

In Texas, lakes sometimes remain low for a long period of time or go completely dry. When such lakes rise, so does their priority for stocking. New or renovated reservoirs also generally go to the top of the list. Thus, West Texas reservoirs rebounding from a decade-long drought were first in line to receive fish in 2005. Lakes impacted by golden alga kills are also restocked when conditions improve. Community fishing lakes, which provide close-to-home fishing for urban Texans, also rank high on the stocking list.

“Our goal is to use stocking to complement the other management tools we have — regulations and habitat manipulation — to make fishing as good as we can make it in Texas,” says Bill Provine, management and research chief for TPWD’s Inland Fisheries Division.

Without stocking, Texas anglers would not enjoy what is arguably the best fishing in the nation, particularly for largemouth bass.

Florida largemouth bass, striped bass and smallmouth bass are not native to Texas. Yet all three species are very popular with anglers. How they got here, and why, is a tale of a growing state with few natural lakes and several semiarid regions.

“Two hundred years ago Texas had 191,000 miles of streams and rivers flowing unimpeded to the Gulf of Mexico — and one natural lake,” says Provine. “Today, there are more than 800 impoundments and few unregulated stretches of river. Reservoir construction increased the amount of aquatic habitat in the state while dramatically changing most of the original habitat. Consequently, TPWD had to develop a fisheries program based almost entirely on environments alien to native fish populations. TPWD has used hatchery-raised fish to meet the challenges of these altered systems while diversifying fishing opportunities.”

Lacking adequate numbers of predators, the new reservoirs tended to become overpopulated with forage fish and undesirable species. For a time fisheries managers tried controlling populations by removing unwanted fish, but that was expensive and did little to improve the quality of fishing. Introduction of new species was the next option. “We went through a laundry list of species from this and other countries to try to take advantage of this newly created habitat unlike any we had had in Texas,” Provine says. “We looked at Nile perch, peacock bass, walleye, northern pike, muskellunge and corvina.” What was needed was a game fish adapted to large bodies of open water that would feed on the overabundant forage, primarily threadfin and gizzard shad.

Enter striped bass, a marine species that can survive and grow in fresh water. “In 1954, fisheries biologists in South Carolina discovered that striped bass could live in fresh water, when Santee Cooper Reservoir was closed,” says Roger McCabe, a now-retired TPWD fisheries biologist who headed the striped bass program in Texas for three decades. “We brought the first striped bass to Texas in 1967 and stocked them into Lakes Navarro Mills and Bardwell.” Stripers were later introduced into the Brazos, Trinity and Red River systems. Populations in 13 mainstream reservoirs are maintained through annual stockings. Oklahoma and Louisiana have stocked the border reservoirs Lake Texoma and Toledo Bend.

Like salmon, stripers are anadromous, meaning they live in saltwater but spawn in fresh water. Success depends on having water flowing in stream segments long enough to keep the eggs suspended until they hatch, about 48 hours. Some stretches of the Brazos, Trinity and Red have the right conditions, but only Lake Texoma has a self-sustaining striped bass population. For the other reservoirs in Texas, striped bass and hybrid striped bass must be produced in hatcheries. According to McCabe, Texas has the largest striped bass and hybrid striped bass stocking program in the nation.

Stripers feed primarily on shad in reservoirs and can eat gizzard shad that grow too large for largemouth bass to eat. In biologist-speak, stripers convert underutilized forage fish biomass into sport fish biomass. In angler-speak, stripers eat fish no one wants and grow into trophies everyone wants to catch. The current state record for striped bass stands at 53 pounds.

Stripers occupy a vacant niche in artificial environments, mainly open water in reservoirs. Anglers target them by finding schools of baitfish, either by using electronics or watching for birds feeding on baitfish pushed to the surface by predators.

The new reservoirs also had lots of shoreline habitat and submerged structure such as trees, humps, old roadbeds and brush piles. Anglers recognize these things as largemouth bass habitat.

“Most people don’t realize that Florida largemouth bass were introduced to Texas not just because they grow bigger, but also because they are adapted to living in large, open bodies of water,” says Phil Durocher, director of TPWD’s Inland Fisheries Division. Hatchery production began in 1972, and by 1979, Florida largemouths had been stocked into 91 reservoirs statewide.

“The influence of Florida largemouth bass has increased angler catches of trophy-sized bass,” Provine points out. “In 1990, there were only 64 public reservoirs in the state with largemouth bass records exceeding 9.9 pounds. By 2003 there were 154. The Texas state record for largemouth bass stood at a little more than 13 pounds from 1943 to 1980. The current record, 18.18 pounds, was set in 1992.”

It’s worth noting that those changes would probably not have happened at all without the introduction and stocking of Florida largemouths.

It’s also worth noting that stockings of Florida largemouth bass have been carried out evenly across the state. Every part of the state has received Florida largemouth stockings almost exactly equal to its share of surface waters. Almost every place you go, you can catch Florida largemouth bass.

Catching fish is what other TPWD fishing programs are all about, and stocking makes those programs possible. Rainbow trout are stocked in winter in 82 small lakes. For further information:

• Locations of community fishing lakes
• Dates and locations of fish stockings
• The Texas Urban Fishing program stocks fish at approximately two-week intervals from spring through early fall.

“Intensive work with hatchery-raised fish in urban and state park impoundments may become emphasized even more as the Texas population continues to shift to urban areas,” says Provine. “Our present successes with propagated fishes demonstrate that put-and-take and put-grow-and-take fisheries may be better able to withstand fishing pressure than fisheries relying on natural reproduction. If this is the case, the use of propagated fishes and the demands on our hatchery system in Texas are sure to increase.”

One way to meet the increased demands is to maximize the survival of the fish that are stocked. TPWD research studies have shown that as many as 22 percent of stocked fish are eaten by predators within hours after being stocked. That same research has shown how to minimize losses, either by stocking larger fish or protecting fingerlings for the first 24 hours. Both methods are prohibitively expensive at present, but biologists hope to overcome that obstacle someday.

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