Bob Maindelle Guide Lines Sept. 17

Temple police Chief Floyd Mitchell displays a “pygmy” hybrid striped bass he landed while fishing with Bob Maindelle’s Holding the Line Guide Service on Belton Lake on May 2. TPWD has begun investigating the cause of the hybrid striped bass deformities.

Courtesy | Holding the Line Guide Service

As a fishing guide, the next best thing to actually being on the water is having trustworthy peers who are willing to share with me their successes and failures, as I do with them, so as to try to stay in touch with what the fish are doing day to day and week to week.

It was during this process of networking with two other skilled, credible anglers last spring that I began to realize something might be amiss with a portion of the hybrid striped bass population in Belton Lake.

In comparing notes with fellow guide Jason Weisberg of Round Rock and fellow multi-species angler Bill Pasko of Belton, I realized all three of us were beginning to see oddly-shaped hybrid striped bass routinely show up in our catch.

These fish looked like a normal hybrid striped bass that had been compacted down to just 13 or 14 inches in length with most of the “compaction” showing at mid-body, right around the dorsal fin on both the back and in the belly.

As we spoke by phone about these mystery fish, we began referring to them as “pygmies” for brevity’s sake.

One morning in mid-March, my concern peaked when, while fishing with clients out on the main basin of Belton Lake, our catch of over 40 hybrid striped bass included 14 of these “pygmies.”

I decided to reach out to John Tibbs about the matter.

Tibbs is the Inland Fisheries Supervisor for the Texas Parks and Wildlife Division’s Waco District. Tibbs has long been a real ally of recreational and professional fishermen alike, and oversees the stocking of hybrid striped bass into many Central Texas reservoirs, Belton  included.

Characteristically, Tibbs did more listening than speaking, then began to take action.

Tibbs, when presented with some photographic evidence of the issue, immediately went to work to investigate the cause of the deformities anglers had begun to witness.

When Tibbs approached me about providing samples of fish, I responded by letting him know that 100 percent of the “pygmies” I had captured were below the legal length limit of 18 inches.

Tibbs went to bat for Belton anglers at this point by applying for and obtaining a special permit allowing for limited possession of deformed, undersized hybrid striper strictly for the purposes of investigating this issue.

From April 21 through June 14, 14 more “pygmies” were captured for this investigation. Each was tagged and bagged, each had a piece of its anal fin snipped off and preserved in ethanol, and each was frozen whole to allow for future physical and genetic measurements to be made.

Recently, the results from the initial study of those 14 fish came back. Tibbs summarized the initial findings and expressed his plans to continue looking at this issue when the routinely scheduled future samplings are made on Belton Lake.

First, Tibbs indicated that all 14 fish were Palmetto strain hybrid striped bass; 11 of the 14 were stocked in 2015. This means all 14 fish were the result of male white bass milt fertilizing female striped bass eggs. Next, all 11 of the 2015 “pygmies” were produced at the TPWD’s A.E. Woods fish hatchery in San Marcos, and all 11 of the fish stocked in 2015 were produced in the same vat.

Initially, there was some suspicion that back-crossing had taken place, which would have involved a hybrid striped bass successfully spawning with a “full-blooded” white bass in the wild. This was not the case.

TPWD geneticist Dijar Lutz-Carillo, the man responsible for the genetic study on these 14 sample fish said, when asked to speculate about the cause of the deformities, “It really could be any number of things ranging from the extremes of normal phenotypic variation to outlier deformities due to water quality parameters (e.g., dissolved oxygen, ammonium, metals, etc.) or epigenetic modifications associated with gametogenesis or development.”

Tibbs noted that the hybrid stripers stocked in Belton in 2015 (the stocking from which 11 of the 14 sampled fish had come) were stocked as fry versus being stocked as fingerlings. As small as the fry are when they are stocked, it would be nearly impossible to tell at the time of stocking if individual fry had been injured in any way during handling, transport, and/or transfer, given that several hundred thousand such fry are stocked at a given time.

At this time there has not been a single or multiple causes identified for the deformities seen in these Belton Lake hybrid, but the body of evidence about these fish is growing thanks to cooperation between anglers and the TPWD.

Tibbs said he “… doesn’t expect this issue to significantly affect availability of legal-sized hybrids to anglers but will keep a close eye on this issue in future surveys.”

There will be more to follow on this topic as routine surveys are performed on the lake, and I will endeavor to keep the angling public aware of any development via this column.

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