Texas Parks and Wildlife Department Attempts to Repeat Red Drum Enhancement Success

The Texas Parks and Wildlife Department (TPWD) recently reported the release of 750 hatchery-reared southern flounder into Texas coastal waters. This initial stocking “… like the initial redfish release three decades ago, it harkens a new age of coastal fisheries conservation.” Wow! Is this really what they want?

A bit of history
In response to declining red drum stocks in Texas coastal waters, TPWD began releasing hatchery-reared red drum into Texas coastal waters in the early 1980s. These efforts expanded over the years and TPWD now operates two hatcheries dedicated to production of red drum for release into Texas coastal waters.

In the early 1990’s TPWD began attempts to estimate the contribution of hatchery-released fish to red drum stocks in Texas waters. Initially, TPWD compared lengths of hatchery-released fish (smaller) with those of wild-bred fish (larger) captured in seine samples and found that hatchery-released fish represented up to 20% of the fish in their seine samples. I reviewed the original reports of these studies several years ago, when I worked for TPWD. Among all the bays studied, over a period of several years, the most common proportion of hatchery-reared fish in TPWD seine samples was 0%. Occasionally, hatchery fish were captured and in one instance, in the Upper Laguna Madre, when TPWD sampled the exact area in which hatchery fish had been released one month earlier, they found that 20% of the sample consisted of hatchery-released fish. These results were optimistically, but correctly, reported as evidence that up to 20% of red drum in TPWD samples were hatchery-released fish.

Within days, these results were misreported in the popular media as demonstration that 20% of the Texas red drum population was composed of hatchery-released fish. Once this reporting error was committed, no one, not even TPWD, looked back on it. Twenty-percent it was.

Nevertheless, the red drum in TPWD seine samples were young fish and questions remained as to whether hatchery-released fish contributed to the adult population.

In 2000, TPWD geneticist Rocky Ward reported results of an assessment of the contribution of hatchery-released red drum to the adult stock. This involved use of hatchery-brood fish that were genetically “marked” by their possession an uncommon gene. Over 6000 red drum collected between 1993 and 1997 were collected in monitoring samples and during creel surveys from Texas bays. These fish were genetically examined and showed no evidence of any increase in the genetic marker. In a nutshell, stocking had little, if any, affect on abundance of adult red drum.

A more recent report, published last fall by Texas A&M geneticist John Gold and his colleagues (Karlsson et al. 2008), reported that 11 hatchery-released fish were among the 970 red drum in samples they collected from random locations within Aransas Bay. Similarly, 30 hatchery-released fish were present among 321 fish they collected from Galveston Bay. Karlsson et al. used techniques that allow them to identify the parents of individual fish, thus, their results suggest that hatchery-released red drum accounted for 1% (Aransas Bay) to 9% (Galveston Bay) of adult red drum in these two bays. Combining results for both bays, an estimated 3% of red drum are hatchery-released fish.

Many fishery biologists in Texas, and elsewhere, are skeptical of the contribution of hatcheries to Texas coastal red drum stocks. The studies cited above, and others, consistently have failed to provide evidence that coastal fish stocks have been significantly enhanced by hatchery-released fish. These results have only reinforced the skepticism of fishery biologists and certainly have does nothing to support the almost mythological 20% reported in the early 1990s. Further, many fishery biologists question whether hatchery-releases add to the population, or merely displace wild-bred fish.

In contrast, hatchery biologists actively promote hatchery-releases of red drum and argue that the above referenced studies prove that hatchery releases have enhanced the red drum population.

I’m sure these studies will continue, but for now, it looks as if two multimillion dollar hatcheries account for, perhaps, 3% of the Texas coastal red drum population. No matter which side of the argument you are on, those are some expensive fish.

References

Karlsson, S., E. Saillant, B. W. Bumguardner, R. R. Vega, and J. R. Gold. 2008. Genetic identification of hatchery-released red drum in Texas bays and estuaries. North American Journal of Fisheries Management 28:1294-1304.

Ward, R. 2000. Genetic marking of red drum. Federal Aid in Sport Fishing Restoration Act, Texas, F-36-R, Project 12. Texas Parks and Wildlife Department, Austin, Texas.