On Wednesday evening, a crew of fisheries biologists from the Texas Parks and Wildlife Department’s regional office in Waco, led by John Tibbs, the Inland Fisheries Supervisor for the Waco District, stocked 633,920 hybrid striped bass fry into Belton Lake near the Leona Park boat ramp.
WHAT IS A HYBRID?
Hybrid striped bass are a man-made cross between full-blooded striped bass and full-blooded white bass. When a female striped bass and a male white bass are crossed, the resulting hybrid is called a Palmetto strain hybrid. When a female white bass and a male striped bass are crossed, the resulting hybrid is called a Sunshine strain hybrid.
All of this year’s hybrid placed into Belton Lake were Palmetto strain hybrid.
Just one day after hatching, and with a length of just a few millimeters, some 50,000 of these fry would be required to fill an average-sized coffee mug. These dainty creatures do not even look like fish quite yet, as they still have their yolk sacs attached to provide nourishment until they begin feeding on naturally occurring phytoplankton and zooplankton.
If all goes well, some small percentage of these fish will reach 18 inches and about 3 pounds by this time in 2021. Although these fry have a long way to go, the process of just getting them to the point of being ready for stocking requires much behind-the-scenes work on the part of Tibbs and his co-workers.
NATURE THROWS A CURVE
In a normal year, during the month of April, Tibbs and his crew drive to the tailrace of the Lake Livingston dam and use electro-fishing tactics to collect large, egg-laden female striped bass. Other teams collect white bass milt (fish semen) from fish primarily in east Texas rivers. Hormone injections are administered to the female striped bass to induce them to release their eggs.
The eggs are fertilized with milt in a hatchery setting and then the fertilized eggs are placed in specialized jars to keep them aerated and circulated, thus preventing the eggs from adhering to the jars and suffocating.
This was not a normal year, however. When Tibbs and crew went to the Livingston dam the week before their intended collection effort, all was well. There were stripers present and egg development appeared to be on track. The following week, flooding conditions in the Trinity River watershed made it impossible to access the river at the ideal time.
By the time the flow reached safe levels, most of the female stripers had released their eggs. This forced TPWD into Plan B, which was to use captive striped bass as the source of eggs for this year’s hybrid crop.
According to Tibbs, this went extremely well, with a relatively small number of captive fish providing over 5 million eggs. Once egg and milt collection was completed, hatchery personnel fulfilled their roles in fertilizing the eggs and then sustaining the resulting organisms. Tibbs and his crew then awaited communication from the hatchery that his region’s portion of the fry were ready for stocking.
For a number of years now, Tibbs’ office has been evaluating the relative efficiency involved in stocking high numbers of inexpensive fry versus lower numbers of much more expensive, but larger, fingerlings.
MAKING A GOOD THING BETTER
Fry are but a few millimeters long and require little care after hatching, as they can be stocked almost immediately thereafter. Fry are able to be transported by the thousands in small boxes by passenger vehicle. Fingerlings, on the other hand, are grown out to two inches in length and therefore must be transferred to a growout pond, then fed, then re-collected, then transported in specialized, aerated tanker trucks.
Thus far, the research has revealed that for much less cost, 10 times as many fry can be produced versus fingerlings. When these fry are stocked, it yields four times the amount of mature, legal-sized hybrid striped bass approximately three years later.
With that understood, Tibbs’ office is now investigating the ideal number of fry to stock. Belton is slated to receive a full stocking of 1.2 million fry in odd years and 600,000 fry in even years. Data will continue to be collected to see which of the stockings is more efficient in terms of fish reaching catchable sizes.
IN THEY GO
The fry Tibbs and his crew stocked Wednesday were just one day old. They were double-bagged in a few gallons of well-oxygenated water, then placed in insulating, protective foam boxes early in the morning at Dundee Fish Hatchery and then transported by vehicle to Belton.
The boxes of fry were placed aboard a TPWD work boat and taken out onto the lake.
The bags containing the water and fry were removed from the foam boxes and placed afloat in the water to let the bag water temperature equilibrate with the temperature of the lake water. This process normally takes 10 to 30 minutes.
Once the temperature of the water in the bags reaches that of the lake, each bag is manually emptied and the small, grey ‘cloud’ of fry instinctively dive for deeper water, away from the bright surface waters.
They are released in the upper part of the Leon Branch near the Highway 36 bridge due to higher levels of phytoplankton and zooplankton in the water compared to the main lake. This gives the fry a good start to life and has resulted in an excellent hybrid striped bass population in Belton.
From that location they grow up and spread throughout the lake.