Joe Castle decided to celebrate his “leap year birthday” on Feb. 29, 2020, with a fishing trip to Lake Nacogdoches.

When he reeled in a whopping 15.34-pound largemouth bass on a Senko wacky rig, his catch proved to be a legacy in more ways than one.

“My initial reaction was that it was a double-digit bass, but when I put it on the scale and realized just how big it was I about fell over,” Castle says.

First, his catch qualified to be a part of the top Legacy Class of the Texas Parks and Wildlife Department's (TPWD) Toyota ShareLunker big-bass program. Second, his bass turned out to be a member of the ShareLunker family tree, with ancestors that were ShareLunkers themselves.

TPWD launched the Toyota ShareLunker program in 1986 as a way to enhance bass fishing in Texas. The program encourages anglers to share their biggest catches for use in TPWD's breeding and stocking program. From its inception, starting with just one fish, a giant bass named Ethel (see opening spread), the program has grown into a nationally recognized initiative that draws anglers to Texas from across the United States and the world. These anglers are in pursuit of largemouth bass and the dream “catch of a lifetime.”

The incredible Legacy Class ShareLunkers - any largemouth bass weighing 13 pounds or more, and caught between Jan. 1 and March 31 each year - grab headlines, but there is another amazing aspect of the program below the surface. It's the driving force of science that makes exciting catches like Castle's possible.

Florida to Texas

Largemouth bass are native to Texas and adapted to live in streams and rivers. A close cousin, referred to as Florida largemouth bass or Florida bass, is native to natural lakes found in peninsular Florida. Florida bass were introduced to Texas in the 1970s.

A severe drought in the 1950s led to construction of new reservoirs in the 1960s and '70s. In 1971, Inland Fisheries Division Director Bob Kemp decided to bring in pure Florida bass to take advantage of all the new habitat created by these reservoirs that mirrored the natural lakes of Florida. These bass were perfect for the brand-new environments.

The fish, acquired directly from Florida, were stocked first in a few private lakes as a test run. They flourished. In 1974, TPWD made the official switch and used pure Florida bass as broodfish for stocking Texas' public waters.

The Florida bass genes, through TPWD's hatchery propagation and stocking efforts, worked their way into reservoir bass populations, and, lo and behold, the fish got bigger and bigger. The state record at the time was a 13.5-pound largemouth bass caught in 1943. That record held until 1980, when a 14.1-pound catch set a new bar. The record was then broken multiple times leading up to Barry St. Clair's 18.18-pound tank (ShareLunker 105) from Lake Fork in 1992. St. Clair's fish still holds the state record, but is a potential new state record swimming in a reservoir at this very moment?

Fish Genetics

Over the years, fisheries biologists at TPWD have been using scientific approaches to better understand why some bass grow larger and how the agency can use this information to grow even bigger bass.

Each year, TPWD fisheries biologists sample fish populations in reservoirs, and the samples have revealed that most bass are hybrids - fish that are a combination of northern largemouth and Florida largemouth bass. Only a small portion of the fish are purely Florida or purely northern.

When Dijar Lutz-Carillo started his job as a geneticist for TPWD in 2004, one of the first things he helped develop was a genetic marker panel for identifying these species and their hybrids.

“We started applying those markers to all the big fish that were coming in,” says Lutz-Carrillo. “What we saw was that even though the populations of these reservoirs were almost all hybrids, nearly half of the really big fish that were tested were Florida largemouth bass. The other half were hybrids, and of those, almost all of them had most of their genome derived from the lineage of the Florida largemouth bass.”

In other words, Florida largemouth bass were a small percentage of the fish in the population but a large percentage of the big fish being turned in through the ShareLunker program.

With this new knowledge in hand, TPWD began to prioritize spawning big fish that were purely Florida largemouth bass. Male offspring from the big fish were kept as broodfish to spawn with Legacy Class ShareLunker bass loaned by anglers (these are always females). This was the first step in the process toward what now has become the landmark Lone Star Bass program (which we'll dive into more in a bit).

TPWD Inland Fisheries Division biologists are now taking the next step in their genetic exploration.

“What we are studying now is if there are genetic markers that are indicative of a fish attaining a large size independent of its ancestry,” says Lutz-Carrillo. “The question is, what if we could identify what it was in the Florida bass genome — the specific genetic variation — that is contributing to those differential size effects? If you could identify those, then you could potentially include more hybrids in the Lone Star Bass spawning program, and it would allow you to identify fish with good size potential without having to wait 10 years to find out. You could test the fish when they are young and retain these fish for the program. It would eliminate the need to wait for a decade to make that determination.”

TPWD initially screened around 150 fish over 13 pounds and 150 fish that biologists thought would be good in a control group. The control group of fish are less than 13 pounds. They are standard-sized fish that were collected from Texas reservoirs or during the initial broodstock collections for the hatchery programs.

Researchers are in the process of screening them to determine if indeed there are specific genetic markers that can identify fish with big growth potential.

Lone Star Bass

Now it's time to talk about Lone Star Bass.

The Lone Star Bass program is the latest scientific advancement and a game changer for bass fishing in the state of Texas. In 2022, the Texas Parks and Wildlife Department began stocking Texas lakes with pure Florida strain largemouth bass bred exclusively from broodfish produced from Legacy Class (13-plus pound) entries into the ShareLunker program. This is in addition to the offspring that are produced from each year's Legacy Class fish.

Since 1986, approximately 1.8 million fingerlings from the spawning of Legacy Class ShareLunkers have been stocked back into public Texas lakes. The Lone Star Bass program now allows TPWD to stock 6 million to 8 million fingerlings with ShareLunker genetics across the state each year. The jump from 1.8 million over 40 years to 6 million to 8 million each year illustrates what a monumental step this is for TPWD and the ShareLunker program.

What Science has Shared

each year after the ShareLunker collection season, the data analysis provided by Lutz-Carrillo and his team reveals some incredible findings - mother and father relationships, siblings, cousins and other connections to previous ShareLunkers. We'll focus on one ShareLunker family tree that is truly remarkable.

“One of our most impressive genetic trees comes all the way back from ShareLunker 9,” says Natalie Goldstrohm, Toyota ShareLunker program coordinator. “We used her offspring as one of our very first male broodfish. We are discovering fish in this genetic tree year after year, and one thing that we feel is very important is at the bottom of the tree are multiple lake records.”

Let's jump in our time machine and venture back to 1988 where the tale begins. Angler Troy Johnson headed out to Gibbons Creek Reservoir (no longer a public water body) just east of Bryan/College Station on Jan. 15. Johnson reeled in Legacy Class ShareLunker No. 9 that day, which weighed 16.13 pounds and still holds the water-body record. Johnson's decision to share his fish with the fledgling ShareLunker program had a huge ripple effect.

ShareLunker 9's family tree includes five Legacy Class Lunkers. ShareLunker 566 weighed 13.07 pounds and was caught by angler Ryder Wicker on Feb. 10.

Anglers are Essential

The moral of the story is that these unique fish are made possible through the valued partnership with anglers who loan their fish and submit their catch information to the program.

“When an angler shares their Legacy Class ShareLunker, we take a small sample of the fish's fin and with that can determine its genetic makeup,” says Goldstrohm. “We can tell whether it's a Florida largemouth bass, a northern largemouth bass or a mix of the two. The genetic analyses that we run are also able to determine if the fish is a recapture, if it's a daughter or granddaughter of a previous ShareLunker, a sister, or has another relationship with a ShareLunker that has been entered into the program.”

Anglers who catch and loan a 13-plus pound lunker earn Legacy Class status and receive a catch kit filled with merchandise, VIP access to the Toyota ShareLunker Annual Awards event and a high-quality replica mount of their fish from Lake Fork Taxidermy. In 2018, the Toyota ShareLunker program was expanded to offer anglers three additional levels of participation for catching bass over 8 pounds or 24 inches in Texas public waters.

“We have always requested that the anglers turn in their DNA samples from their fish,” says Goldstrohm. “They can do that by taking three scales off their fish and sending those into our genetics lab. We can determine all the same information on their fish that we can on the Legacy Class bass. During the 2024 season, we began making a really big push to get these genetic samples from our anglers because of the move to Lone Star Bass.”

The expanded ShareLunker program will provide vital data to TPWD fisheries biologists, and TPWD and Texas anglers will continue to work together to create bigger, better bass in Texas. Suffice to say, the ShareLunker family tree is about to get a lot bigger.

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