The success of a stock enhancement program depends on the survival of stocked fish after release hatchery produced southern flounder paralichthys lethostigma have a high incidence of malpigmentation…

Federal Formula Grant Award Summary

The Texas Parks and Wildlife Department (TPWD) received a $153,350 Formula Grant award from the U.S. Fish and Wildlife Service (USFWS) under the State Wildlife Grants (SWG) Program (CFDA 15.634), effective November 1, 2025 through October 31, 2026. This award funds research to determine the relationship between lighting intensity and malpigmentation in hatchery-reared southern flounder (Paralichthys lethostigma), a species of conservation concern included in Texas' Wildlife Action Plan. Southern flounder stock enhancement programs suffer reduced survival rates due to high malpigmentation incidence in hatchery-produced fish, which increases predation vulnerability. While previous research demonstrated that enriched larval diets reduced malpigmentation rates at TPWD's Marine Development Center in Corpus Christi, significant malpigmentation persisted, suggesting that hatchery lighting conditions play a substantial role in the condition's etiology.

The project deliverables include rigorous laboratory and field testing to establish a reaction norm—the quantitative relationship between lighting intensity and malpigmentation rates—across a range of light conditions observed in both controlled laboratory settings and TPWD hatcheries. Additionally, the research will employ transcriptome sequencing analysis of larvae raised under high and low light intensities to elucidate the underlying biological mechanisms. By establishing this relationship, TPWD hatcheries will gain evidence-based guidance for optimizing lighting conditions to minimize malpigmentation while balancing operational considerations related to larval feeding success and broader hatchery operations. The University of Texas at Austin serves as a sub-grantee, contributing specialized research and laboratory capabilities through its Fisheries and Mariculture Laboratory (FAML) for this conservation research initiative.

The success of a stock enhancement program depends on the survival of stocked fish after release hatchery produced southern flounder paralichthys lethostigma have a high incidence of malpigmentation which almost certainly makes them more vulnerable to predators studies indicate that malpigmentation results from the interaction of multiple genetic and environmental factors including larval nutrition and rearing conditions zhang ET AL 2022 our previous laboratory experiments showed that a diet of artemia enriched with polyunsaturated fatty acids FED during rearing reduced malpigmentation rates implementation of the enriched diet at the tpwd marine development center in corpus christi resulted in a reduced malpigmentation rate 20 compared to the prior year when the diet was not enriched 27 however our laboratory pigmentation rate 5 was still much lower than the dietimproved hatchery rate suggesting that one or more other factors in the hatchery contributed to higher malpigmentation rates preliminary data gathered from the tpwd hatchery in corpus christi and the university of texas marine science institutes fisheries and mariculture laboratory faml strongly suggest that hatchery lighting intensity plays a large role in determining malpigmentation rates in southern flounder the proposed project will rigorously test the relationship between lighting intensity and malpigmentation rate in juvenile southern flounder by raising larvae in a range of light intensities observed in the laboratory and tpwd hatchery the goal of the research is to establish the reaction norm between malpigmentation rate and lighting intensity so that tpwd hatcheries can make informed decisions about optimizing lighting intensity to balance the desired reduction in malpigmentation with other considerations related to lighting larval feeding success hatchery operations etc we further aim to apply transcriptome sequencing of larvae raised under high and low light intensities to understand the mechanism through which lighting intensity affects malpigmentation and which developmental periods are critical for this effect