Achieving Recovery: Nonnative & Sportfish Management
|>||A Recovery Program member assists Provo City workers in moving thousands of migrating carp from the Provo River before irrigation demands cause water levels to drop too low for the fish to survive.|
Introduction of nonnative fish species into Utah Lake, which began in the late 1800s, has changed the lake's fish community dramatically. Thirteen native fish species originally occurred in Utah Lake. Of these thirteen species, only two are still present in Utah Lake today, the June sucker and the Utah sucker (Catostomus ardens), both with extremely low numbers.
At least 24 nonnative fish species have been introduced into Utah Lake and several of these have become established as self-sustaining populations. Those which have been particularly successful include the common carp (Cyprinus carpio), white bass (Morone chrysops), black bullhead (Ameriurus melas), channel catfish (Ictalurus punctatus), largemouth bass (Micropterus salmoides), and walleye (Sander vitreus).
The establishment of nonnative fish in Utah Lake has contributed to the demise of native fish species and to the endangered status of June sucker, likely through predation, competitive interactions, and habitat alteration. Common carp, a nonnative fish introduced in the late 1880's, contribute to all three of these affects in Utah Lake.
By reducing and controlling the numbers of nonnative fish, the lake's ecosystem will become more balanced to support a more diverse aquatic community that will benefit the remaining native fish species. By actively managing the fish community, problems brought on by over fishing certain species, ecosystem imbalances and disproportionate fish biomass ratios can be avoided. The Utah Division of Wildlife Resources has authority for managing Utah Lake's fishery. Current fishing regulations for Utah Lake protect some large-bodied, predatory gamefish such as walleye and bass. Historically, Bonneville cutthroat trout were the natural fish predator in the system.
|>||The establishment of nonnative fish in Utah Lake has contributed to the demise of native fish species and to the endangered status of June sucker, likely through predation, competitive interactions, and habitat alteration.|
At this point, scientists are uncertain about what combination of species would contribute to maintaining a healthy and balanced aquatic community in Utah Lake that fosters the recovery of June sucker. Originally the lake supported Bonneville cutthroat trout as the top predator. However, because of changes in habitat, it is uncertain if Bonneville cutthroat trout could survive in the lake today. Research regarding options will provide insights that can be applied to the long-term management of Utah Lake aquatic community.
In Utah Lake, the reduction and control of common carp represents a significant challenge. Common carp have a competitive advantage over native fish, including the endangered June sucker. In the most recent lake-wide survey conducted, common carp represented an overwhelming 91 percent biomass in the lake. Common carp in Utah Lake are a destructive force within the energy network of the lake's ecosystem and cause conditions that promote their survival over other species. Total elimination of carp from such a large lake system is not feasible at this time. However, studies have shown that benefits to shallow lake systems can often be achieved with a 75 percent reduction in bottom-feeding fish populations as long as the reduced numbers can be maintained.