Gene Jarka stumbled into big.
He was “perusing some of the lake reports” on ifishillinois.org when he “stumbled across this information from the 2023 stocking” of 432 8- to 10-inch alligator gar at Hennepin-Hopper lakes.
I’ll listen to anyone slinging “peruse.”
I guessed that was as far north as alligator gar have been. Hennepin-Hopper (a favorite of both Jarka and myself) is at The Wetlands Initiative’s innovative restoration south of Hennepin on the Illinois River.
“The Hennepin-Hopper site is the farthest north that the IDNR has stocked alligator gar,” emailed Illinois Department of Natural Resources fisheries biologist Rob Hilsabeck, involved with the reintroduction of alligator gar in Illinois since the beginning.
Solomon David, assistant professor of aquatic ecology at the University of Minnesota and fearless leader of GarLab (solomondavid.net), said it was as far north as they have been reintroduced in the United States.
“Historically the best guess is the Peoria/Pekin area on the Illinois River as the northern extent of their range,” Hilsabeck emailed. “However in modern times, the IDNR has documented an 15-inch long alligator gar from the West Branch of the DuPage River below the Fawell Dam in Naperville by an angler catch in 2021.”
Jon Reith caught that while bass fishing in late September (Sun-Times, Oct. 6, 2021).
“And in 2017, the IDNR Asian Carp crew collected a 45-inch long fish from the Starved Rock Pool in the Illinois River,” Hilsabeck continued. “Both of these fish were returned back alive to the locations of capture. We guess the DuPage River fish was an aquarium release, and the Starved Rock Pool fish migrated from one of our early Illinois River stockings?”
Before 1977, alligator were unregulated in Illinois. Then, as the “IDNR Fish Species Management Plan for Alligator Gar (Atractosteus spatula) in Illinois” notes, “From 1977 to 1994, the species was listed as a state-threatened fish under the Illinois Threatened and Endangered Species Act. In 1994, the alligator gar was delisted and considered to be extirpated.”
The U.S. Fish and Wildlife Service began a multi-state effort to reintroduce alligator gar in the 1990s. Illinois became involved in 2010. Before reintroduction began, the last known alligator gar, about 7 feet in length and weighing about 130 pounds, in Illinois was caught in 1966 from the Cache-Mississippi Diversion Channel in Alexander County.
FWS describes alligator gar as “one of the largest freshwater fish in North America. They are also sometimes referred to as a living fossil because scientist can trace them back 100 million years in the fossil record.”
The IDNR notes alligator gar are the biggest fish native to Illinois, where there are three other gar: longnose, shortnose and spotted.
Make that really big. The International Game Fish Association’s recently approved all-tackle record is 128.37 kilograms (283 pounds) for an alligator gar 8 feet, 4 inches long, caught by Arthur Weston on Sept. 2, 2023, from Sam Rayburn Lake in Texas.
Alligator gar grow fast, too, even in northern climates.
“In 2023, the largest alligator gar collected by the IDNR from Powerton Lake [near Pekin] was right at 60 inches in length and 60 pounds,” Hilsabeck emailed. “On Aug. 1, 2023, eight alligator gar were collected by IDNR Fisheries from the intake canal at Powerton Lake. Five of these fish were 14 years old, and they were stocked and PIT tagged as 2-year-old fish on June 9, 2011, into Powerton Lake. On Aug. 1, 2023, they had an average length of 1,509 millimeters (59.4 inches) and 26,960 grams (59.4 pounds) each.”
The Hennepin-Hopper stocking is real-time, real-life use of climate data.
Hilsabeck pointed to a master’s thesis by Jory Bartnicki, “Thermal Tolerance of Alligator Gar (Atractosteus spatula),” for Jackson College of Graduate Studies at the University of Central Oklahoma.
One conclusion took into account variability of climate change and how it might impact expansion of the range of alligator gar: “Reproduction and survival of larval alligator gar at the northern edge of its range may be aided by a warming climate, however yearly recruitment may be impacted by extreme temperature fluctuations and other ancillary effects beyond temperature (Ficke, Myrick & Hansen, 2007). Results from this study can be applied to future studies aimed at conservation and management of alligator gar. For example, our findings may aid in delineating the potential northern extent of alligator gar distribution given current and projected climate data.”
“Potentially this centroid location may shift from central Louisiana to South Central Illinois!” Hilsabeck emailed. “Our current IDNR Fisheries stocking evaluation methodology for alligator gar looks at multiple factors such as preferred habitat, forage base and research potential.”
Hennepin-Hopper fits all three.
