18 / OutdoorIllinois January 2007

Many of the 31 fishspecies in Illinois listedas endangered orthreatened are speciesadapted and depen-

dent on the slack-water habitats onceprovided by backwater lakes, wetlands,swamps and meandering streams. Asthese habitats were destroyed for devel-opment and agriculture, the fishesdependent on them declined—or disap-peared completely.

The adaptations to life in water withlittle or no current may also save themfrom extirpation (extinction at the locallevel) as biologists are establishing pop-ulations in aquatic refuges in ponds andsmall lakes. The aquatic refuge practicehas been used successfully across thenation for many years, with the desertpupfish aquatic refuge project drawingbroad news coverage.

In Illinois, the first aquatic refuge forendangered and threatened fish specieswas established in Lake County in the1990s by Integrated Lakes Management.Four fish species from natural glaciallakes of northeastern Illinois werestocked into an urban detention pond at a

subdivision in Grayslake. The blackchinshiners (Notropis heterodon), blacknoseshiners (N. heterolepis), Iowa darters(Etheostoma exile) and banded killifish(Fundulus diaphanus) have reportedlythrived in the detention pond, ensuringtheir continued existence in the state.

In 2004, a cooperative effort betweena University of Illinois Restoration Ecologyclass and the Department of NaturalResources Division of Fisheries was initi-ated to establish an aquatic refuge forrare fish species of the Sangamon Riverbasin. The 1.3-acre Mansion Pond atAllerton Park (Piatt County) was drainedin the spring of 2004 and all fish removed.After minor repairs, landscaping, and re-filling of the pond, lake chubsucker(Erimyzon sucetta) from Crane Creek inthe Lower Sangamon River basin werestocked. Two additional species, the star-head topminnow (F. dispar) and ironcolorshiner (N. chalybaeus), both state-threat-ened, were released in the spring of 2005.Successful spawning was observed in2005. A U.S. Fish and Wildlife Servicegrant is supporting management of aquat-ic vegetation in the pond.

Future planned stockings of addition-al rare fish species from the Sangamon

River basin include obscure speciessuch as the redspotted sunfish (Lepomisminiatus) and mud darter (E. asprigene).As additional species are added, pondmanagement becomes tricky as allspecies need to co-exist and prosper.One dominant and destructive speciescould eliminate the other species fromthe small pond.

Genetic diversity is another issue tocontend with. A sizable population witha large number of adults needs to beestablished to help maintain a high levelof genetic diversity—a population ofclosely related, inbreeding individuals isnot desirable in the refuge or in the wild.

Aquatic refuges are not the ideal situ-ation for maintaining biological diversity inour rivers and lakes, but simply an insur-ance plan to save species from beinglost. As lost habitats are restored throughconservation efforts by the state and fed-eral governments and conservation orga-nizations, fish reared in refuge popula-tions can once again populate our back-water lakes, wetlands and streams.

—Trent Thomas, Region 3 StreamsBiologist, DNR Division of Fisheries

Aquatic RefugesPhotos By Trent Thomas

Multiple organizations work toward developing refuges asa tool in managing rare fish species.

Starhead topminnow (Fundulus dispar)Starhead topminnow (Fundulus dispar)

Mansion pond aquatic refugeMansion pond aquatic refuge