Ongoing research by the Florida Fish and Wildlife Conservation Commission (FWC), suggests that fishing beds for the Florida strain of largemouth bass has little, if any, impact on populations--- if those fish are not harvested.
Results "indicated that fish captured during the spawning period contributed significantly to fall recruitment, despite being removed from their nests," reported Nick Trippel and other biologists who participated in two projects.
They added, "Genetic analysis of over 3,249 Florida bass fall recruits collected over two years provided evidence that nest fishing may not significantly impact the number of adults contributing to reproduction or the average number of recruits produced per adult."
In this study, researchers set up hatchery ponds, each stocked with 10 pairs of mature Florida bass. For two years, half of the ponds were fished and the other half were not. If caught, fish were held for one hour and then released. Biologists snorkeled the ponds every other day to document the number of nests made and confirm that the nests in the fished ponds were being pressured.
After the spawn, the ponds were left alone until October, when they were drained and the number of young produced in each was counted. Using fin clips to obtain DNA, biologists determined the parental contribution from each pond.
Genetic results revealed that fish that were caught off nests still contributed as many juveniles to the recruited year class as did fish that were not caught, they reported. "These results reveal that fishing for nesting Florida Bass likely does not have any negative population level impacts."
In the other study, conducted on three lakes during the spring of 2012 and again in 2015, they observed nests that were randomly placed in three test groups: never fished, catch-and-immediate release, and catch and hold for one hour, before being released 1,000 meters down the shoreline.
"There were no statistical differences in nest success rates between the three treatment groups: 32 percent for controls, 27 percent for catch-and-release, and 27 percent for catch and hold," the biologists said. "Lake, male size, and brood stage were better predictors for nest success rates than angling treatments were. Nest success was higher for smaller males than larger males."
The length of the spawning season likely helps explain why fishing for bedding bass has little if any negative impact. Mike Allen, a fisheries expert at the University of Florida, reported graduate student Stephanie Shaw found the average male raises at least two broods a year.
"The long spawning season in the southern states makes this feasible," he said. "It's less likely that males can successfully raise more than one brood in the northern states, where total spawning duration may be only a period of two to three weeks."
Allen added that bass are not "total spawners," as are trout and salmon. Rather, they are "batch spawners," which means their eggs are spread over multiple spawning events yearly. "Genetic studies have confirmed that female bass spawn with multiple males across a given spawning season," he said.
Still, all of this is not to say that bed fishing could not have an negative impact on bass populations in some cases. "Bed fishing that involves a high harvest component may display results significantly different than this experiment (test ponds)," the FWC biologists said.
"However, we feel that results are applicable to bass fisheries around Florida, as the majority of bass being caught, 70 to 99 percent, are voluntarily released and harvest rates are less than 10 percent."
Additionally, they cautioned, the pond study was not designed to measure "deleterious impacts" that might be associated with fishing specifically for trophy bass.
"However, this study was designed to simulate a worst case scenario in which every nest created throughout the entire spawning season was vulnerable to angling. This is likely not the case in larger public waterbodies with higher habitat complexities."
And finally, here's a revelation that will not surprise many anglers who have been frustrated in their attempts to entice bedding bass: "We also saw that catch rates of Florida bass while on nests were lower than expected, suggesting that Florida bass are less vulnerable to angling than previously thought," the biologists said.