A fish biologist at Utah State University told a symposium audience that carp-removal efforts in Utah Lake have produced visible ecological improvements but have not yet translated into measurable water-quality gains.

"Carp are very detrimental to the ecosystem and native fish, as they have this destructive benthic feeding behavior, which stirs up sediments and uproots vegetation," the presenter said, summarizing why managers began removal efforts in 2009.

The presenter said monitoring results through 2024 show a substantial decline in carp biomass, with the lowest biomass observed roughly between 2017 and 2019 and a modest uptick afterward. The reductions have coincided with an increase in the number of aquatic-vegetation species found along shoreline sampling sites and with higher abundance of preferred prey — zooplankton and aquatic insects — which in turn has improved the body condition of June sucker and sport fish.

"We've gone from a few 100 in the late 19 hundreds or 19 nineties to tens of thousands today," the presenter said of adult June sucker counts, while noting that young-of-year individuals remain scarce, a pattern the presenter linked to poor water quality and low densities of submerged aquatic vegetation that juvenile fish use for refuge.

Despite the positive biological signals, the presenter said the team has not observed a decline in in-lake nutrient concentrations (total phosphorus) or an increase in submerged-vegetation density. "We have not seen a decrease in nutrients in the lake," the presenter said, adding that the team has removed "many tons of total phosphorus" via carp removal but that external nutrient inputs likely explain the persistent concentrations; the exact mass removed was not specified.

The presenter identified three major challenges to restoring a clearer, vegetation-dominated lake: suppressing carp populations further and maintaining low biomass, reducing watershed and wastewater nutrient inputs, and addressing large lake-level fluctuations that make it difficult for submerged vegetation to persist. On the suppression target, the presenter said the horizontal line on their plot "is based off of recommendations from the literature" and that the program approached but did not quite reach that goal.

The talk stressed that wastewater-treatment improvements may help but are not the sole solution. The presenter argued that combining continued carp removal with active reductions in nutrient inputs is the most promising path to improve water quality and aquatic vegetation, while acknowledging that lake-level management is constrained by storage needs, costs and climate variability.

No formal policy decisions or votes were announced during the presentation. The presenter said undergraduate research (a thesis by student Matt Cutler) will investigate whether the rate or timing of lake-level changes matters more than absolute level for vegetation recovery. The presenter closed by acknowledging support from the June Sucker Recovery Program, the Utah Division of Water Quality, the Division of Wildlife, the local water conservancy district and Utah Lake Authority staff.

The research team said sampling and analysis will continue; the results presented covered 2009 through 2024 and will inform managers weighing additional carp-suppression strategies and watershed nutrient controls.