Why Is DEEP Removing Triploid Grass Carp from Candlewood Lake and Squantz Pond?
Sterile Triploid Grass Carp were stocked into Candlewood Lake in 2015 and 2017 to control invasive Eurasian Watermilfoil. However, during 2022, the coverage of all submerged aquatic vegetation in Candlewood Lake dramatically declined to the point that it was largely absent from the lake. Submerged aquatic vegetation is an important habitat that supports healthy fisheries and water quality. It is the position of the DEEP Fisheries Division that active removal of grass carp from the lake is necessary for the submerged aquatic plant community in Candlewood Lake to recover to desirable levels in a timeframe that minimizes adverse effects to fisheries resources and lake stakeholders. Relying on natural mortality alone, it could take upwards of 20 years for the carp population to decline to levels that allow for the recovery of the aquatic plant community. It is the position of the Fisheries Division that such an extended timeframe is unacceptable as it would negatively impact fisheries resources and lake stakeholders. Consequently, the direct removal of grass carp from Candlewood Lake is necessary.
In May 2023, CT DEEP Fisheries staff conducted a pilot Triploid Grass Carp removal program over the course of 3 days, using a combination of boat-based electrofishing and large mesh gill nets. During the 3-day pilot program, a total of 118 grass carp were removed from Candlewood Lake. Building on that successful pilot program, removal efforts continued in 2024 and the Fisheries Division has since removed a total of 460 Triploid Grass Carp.
Grass carp removals are planned for the 2025 season and will continue until vegetation recovery is observed. Based on an analysis of a similar lake that experienced vegetation loss due to grass carp and subsequent recovery, there is potential that vegetation recovery could be achieved with the removal of an additional 100-600 carp. It is important to note that there is a level of uncertainty in these estimates and decisions related to additional carp removals will ultimately be guided by conditions observed in the lake. Once enough carp have been removed for vegetation recovery to begin, there is evidence that vegetation could fully recover within 3 years.
The CT DEEP Fisheries Division is enlisting the help of anglers to remove Triploid Grass Carp from Candlewood Lake and Squantz Pond (which is connected to Candlewood Lake and stocked with Grass Carp in 2017). Removal via angling represents a unique opportunity for anglers to target Grass Carp and directly support science-based fisheries management. Bow and Arrow fishing, while currently legal for Common Carp, is not currently an allowed method for Triploid Grass Carp. If you would like to participate, please use the following links to register as a volunteer angler, report your catch, or view the submitted catches to-date on our public dashboard.
Register as a Volunteer Angler
Tactics and Tips to Catch Grass Carp
Please contact the Fisheries Division with any questions.
Phone: 860-424-FISH (3474)
E-mail: deep.inland.fisheries@ct.gov
Content last updated in April 2025.