Least Chub Candidate Conservation

Least Chub Candidate Conservation

Jim Muck

The least chub (Iotichthys phlegethontis) is a small minnow endemic to the Bonneville Basin of Utah. Historically, it was widely distributed in freshwater ponds, swamps, springs, and tributaries around the Great Salt Lake, Utah Lake, and Sevier Lake. Populations were also abundant in springs within the Snake and Utah valleys.

A decline in the distribution and abundance of the least chub was first noted in the 1940’s and 1950’s. Habitat loss and degradation have been identified as major causes for this downturn. Livestock trampling and grazing along streams and spring complexes reduced or eliminated least chub habitat due to impacts on water quality and riparian vegetation. Other threats to the least chub include nonnative fishes, water diversions, and environmental damage due to mining and oil and gas development.

Surveys indicate that where nonnative fishes were introduced, few if any least chub remain. Introduced game fishes such as largemouth bass (Micropterus salmoides), rainbow trout (Oncorhynchus mykiss), common carp (Cyprinus carpio), and brook trout (Salvelinus fontinalis) are predators historically stocked into least chub habitat. Other nonnative fishes, including the mosquitofish (Gambusia affinis), rainwater killifish (Lucania parva), and plains killifish (Fundulus zebrinis), have been introduced into least chub habitats as well. These fish are potential competitors with the least chub because of similarities in their diets.

Since 1980, the Fish and Wildlife Service (FWS) has conducted periodic reviews of the least chub’s status. Based on its reduced range, the lower population numbers, and the continued threats to the species’ survival, we proposed in 1995 to list the least chub as an endangered species and to designate critical habitat. The known distribution at the time was limited to five spring complexes in a small desert area known as Snake Valley.

Due to the listing moratorium imposed by Congress in 1995, further action on the least chub proposal was postponed. The moratorium (which lasted about one year) and a recission of $1.5 million in listing funds resulted in a serious backlog of species proposed for listing. During the moratorium, the FWS, Utah Department of Natural Resources, Bureau of Land Management (BLM), Bureau of Reclamation, Utah Reclamation and Mitigation Conservation Commission, Confederated Tribes of the Goshute Reservation, and Central Utah Water Conservancy District developed a Conservation Agreement for the least chub in Utah. The goal is to ensure the long-term survival of the least chub within its historic range and assist in the development of rangewide conservation efforts. The last signature to the agreement was obtained on April 2, 1998.

Since the proposal to list the least chub and the development of the agreement, numerous conservation actions have been implemented. Extensive surveys throughout least chub habitat have identified populations in three additional locations: Lucin Pond in Box Elder County, a spring complex in Juab County, and a spring complex in the Sevier River drainage in Mills Valley, Sevier County. The Lucin Pond population resulted from a 1989 least chub introduction effort that earlier was thought to have failed. Additionally, least chub were introduced in 1998 into two springs at the Fish Springs National Wildlife Refuge in an attempt to establish additional populations within the species’ historic range. Nonnative species in these springs were removed the previous year.

The BLM has conducted a variety of habitat protection and enhancement activities for the least chub. In 1995, it constructed a cattle exclosure at the Gandy Salt Marsh Complex in Snake Valley. It then entered into an agreement with a private landowner to fund an additional cattle exclosure and a small dam to control water releases into occupied least chub habitat. The BLM has also conducted several studies on the species’ habitat needs.

The Utah Reclamation Mitigation and Conservation Commission has purchased 85.5 acres (35 hectares) of wetland habitat occupied by least chub. Negotiations are underway to acquire either a conservation easement or fee title for an additional 20 acres (8 ha) of land to protect other sensitive habitat. The State of Utah is in discussions with local county governments to agree on ways to protect occupied least chub habitats on private land.

Additional conservation measures planned or already implemented include a change in the State of Utah’s policy on fish stocking, development of a warm water fish hatchery to promote range expansion of native aquatic species, genetic analysis of all known least chub populations, and use of aerial photography to identify potential survey and reintroduction sites within historic least chub habitat. The genetic analysis will provide information for developing broodstock for the planned hatchery and for reintroduction.

Based on the progress we have made in carrying out the conservation measures identified in the agreement, the least chub’s decline has been replaced with population increases and an extension of the current known range. The improved status and the commitments made by signatories to the Conservation Agreement led the FWS to withdraw the listing proposal on July 29, 1999. It seems clear that the continuing conservation efforts will ensure healthy least chub populations and habitat for the future.

Jim Muck is a Fish and Wildlife Biologist with the FWS Utah Ecological Services Field Office in Salt Lake City.

COPYRIGHT 1999 U.S. Fish & Wildlife Service

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