Kentucky Fish and Wildlife researchers say they have identified genetic markers tied to bigger native largemouth bass, a finding they believe could eventually help improve trophy bass potential in public waters across the state.
The discovery comes through the agency’s Thoroughbred Bass Program, a long-term effort aimed at selectively breeding Kentucky largemouth bass that carry those markers and stocking their offspring in lakes and other public waters.
Biologists in the Kentucky Department of Fish and Wildlife Resources’ Fisheries Division worked with the Center for Aquaculture Technologies on the study. According to the agency, the work marks a significant step in a decades-long challenge of trying to improve largemouth bass size potential in colder climates without relying on non-native fish.
“For more than 50 years, biologists have been trying to increase the size potential of largemouth bass,” Fisheries Division biologist Adam Martin said in a release. “In many states to our south, that effort involves stocking non-native Florida bass or first generation (F1) hybrids. Stocking Florida bass has increased bass size in many lakes in warmer climates, but despite other attempts, it hasn’t worked so far in areas colder than southern Tennessee.”
Martin said more northern states such as Kentucky have not had strong options for improving genetics until now.
The research involved a genome-wide association study using whole-genome sequencing. Fisheries staff collected fin clips from 300 largemouth bass from waters across Kentucky, including 150 fish weighing more than 5 pounds from 30 lakes and 150 slower-growing bass under 3.5 pounds taken from the same lakes. Officials said all samples were confirmed as pure largemouth bass before sequencing began.
Researchers then examined more than 3 million genetic markers per fish to identify markers commonly found in trophy bass but rare in smaller fish.
State officials said the findings now give biologists a way to screen broodfish for both genetic purity and desirable growth traits. Fish carrying the strongest combination of markers could then be bred in hatcheries, with their offspring eventually stocked into public waters.
Over time, those selectively bred fish could reproduce with wild bass and gradually spread the desired growth genetics through wild populations, Kentucky Fish and Wildlife said. The state plans to market fish produced through that effort under the name “Thoroughbred Bass.”
“This process is very similar to the traditional selective breeding programs used in agriculture for millennia,” Fisheries Division Assistant Director Jeff Ross said. “The only difference is that we are using genetic markers to pick which fish to breed. Most importantly, we can use bass caught right here in Kentucky - which preserves local adaptation and genetic integrity.”
Agency leaders said the program is intended as a long-term, science-based investment in Kentucky’s bass fisheries.
“The Thoroughbred Bass Program represents a science-driven, sustainable investment in Kentucky’s bass fisheries,” Fisheries Division Director Dave Dreves said. “By combining advanced genetics with traditional hatchery practices, we are working to ensure that future generations of anglers have the opportunity to continue to catch exceptional bass in Kentucky waters.”
Officials also said the program could help offset the effects of angling pressure, which some research suggests can influence fish genetics by disproportionately removing larger or more aggressive bass from a population. Introducing more fish with genetics tied to larger size could help strengthen those fisheries over time.
Despite the breakthrough, anglers will have to wait at least another year before the first selectively bred fish are produced.
Martin said the first production of Thoroughbred Bass had been anticipated for 2026, but the department is still waiting on manufacture of the screening panel needed to identify trophy markers in broodfish. Because bass spawn only once each year, that delay means the state will likely miss this year’s breeding window.
Biologists will instead spend the spring and summer collecting and testing hundreds of wild largemouth bass to prepare for 2027 production, according to the department. Additional trophy bass from around the state also will be tested to further verify the markers and determine which ones are most important.
Kentucky Fish and Wildlife said more information is available in the Thoroughbred Bass Program interim progress report posted on its website.
