Arkansas Study Looking at Stocking Contribution of Advanced Fingerling Largemouths

HOT SPRINGS – Fisheries biologists with Arkansas Game and Fish Commission are always interested in evaluating how stocking programs are working in the many waterways of The Natural State, all while working to get the agency, the resource, and the people of Arkansas a good return on its investment.

One way AGFC hatcheries are improving both largemouth and Florida bass production is by rearing advanced fingerlings to stock in area lakes. In the past, hatchery staff have reared bass to fingerling size, about 1½ to 2 inches, and released them in lakes in AGFC’s stocking program. Hatchery staff have been researching and evaluating different techniques to rear bass to approximately 4 inches for a pilot study. When these advanced fingerlings reach about 4 inches, they are branded with liquid nitrogen to create an identifiable mark and then taken to study lakes as part of an ongoing research project with the AGFC Black Bass Program.

Dennis Fendley, hatchery biologist at AGFC’s Andrew Hulsey Fish Hatchery, said “When a bass reaches approximately 2 inches in length, its diet shifts from eating insects to feeding on fish, and that often means dining on their smaller cohort. In a production setting this increased cannibalism leads to a reduction in numbers of fish available for stocking. This is the same trend seen with walleyes, stripers and other predatory fish.”

A pilot study for rearing 4-inch advanced fingerlings is underway for largemouth and Florida bass at multiple AGFC fish culture facilities. At these culture facilities hatchery staff are evaluating how different feeding regimes and food sources affect the growth rate of bass fingerlings. With the assistance of the hatchery staff working to increase the size of stocked bass biologists hope to increase the survival rate of stocked fish against bigger bass and other predators within the system. A larger fish, in theory, has a better chance of survival.

According to Colton Dennis, AGFC Black Bass Program coordinator, “When you stock bass fingerlings that are 1-2 inches long, a 15 percent survival rate is considered a success. One question we are trying to answer is, ‘can a better survival rate be obtained by stocking fewer but larger bass?’ The biologists also have to determine if the value of the stocking contribution outweighs the cost of rearing a larger fingerling.”

Fendley says it’s not just a matter of food.

“It costs more to feed advanced fingerlings, and it takes more pond space that could be used for more production of smaller fingerlings so there is a trade-off.” Fendley stated “The hatchery can rear larger fingerlings to meet the needs, but you can potentially only rear 80,000 to 100,000 advanced 4-inch fingerlings in the acres where a million 2-inch fingerlings were reared, increase quality but decrease quantity.”

Jeff Buckingham, AGFC Black Bass Program biologist, has designed a pilot study for the program to evaluate the stocking contribution of the stocked branded fish in selected study lakes.

“Biologists will start sampling the study lakes approximately one month after stocking,” Buckingham said. “Bass will be collected and examined for the identifying brand, add an additional identifying mark, and then release them back into the lake. The additional identification mark will serve to identify fish that have already been collected at least once during sampling to avoid those fish being counted more than once in the study. Sampling will continue until the spring approximately every 30 days to search for branded fish in the study lakes.

“During sampling if we collect and release 100 bass from a study lake and 10 have a brand then that’s a 10 percent survival rate. If it’s 20 fish? That’s even better,” Buckingham said. “The overall goal is to provide a bigger bang for our buck for both the resource and the people of Arkansas.

Sampling data of the study lakes stocked with the 4-inch advanced fingerlings will also be shared with AGFC fisheries pathologist. Ongoing genetic testing of bass fin clips will provide agency staff a better evaluation of the success rate of Florida bass stockings and how Florida bass coexist with native largemouth bass in Arkansas lakes such as Millwood, DeGray, Ouachita, Columbia, Chicot, Atkins and SWEPCO. Dennis says there are a lot of moving parts in the pilot study, and will take a combined effort of hatchery staff and field biologists to pull it off.

“We are evaluating a lot of different strategies with our bass right now,” Dennis said. “Everything from how we rear bass on our hatcheries, to the effectiveness of our stocking programs, and evaluating a couple of different things on stocked fish once they get recruited into a lake.”

The branded advanced fingerlings are being stocked in different study lakes around the state. Branded Largemouth Bass in the study are being stocked into Lake Frierson and Craighead Forest Lake, while branded Florida Bass are being stocked into Gurdon Lake and Dr. Lester Sitzes III Bois D’Arc Lake.