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Borax Lake Chub

 

Borax Lake Chub Borax Lake chub Gila boraxobius is represented by a single population that inhabits a 4.1 hectare geothermally-heated alkaline lake in Harney County, Oregon. This species was listed as endangered under the federal Endangered Species Act in 1982. In 2005, the Oregon Department of Fish and Wildlife's Native Fish Investigations Project initiated a study to 1) monitor population abundance of Borax Lake chub, 2) evaluate ways to reduce handling of Borax Lake chub when monitoring population abundance both by modifying previous mark-recapture protocols and by developing snorkeling survey protocols to use as an alternative to mark-recapture estimates, 3) monitor habitat conditions, and 4) develop a long-term monitoring strategy.

The Borax Lake chub is a small minnow endemic to Borax Lake and adjacent wetlands in Oregon's Alvord Basin (Williams and Bond 1980). Borax Lake is a natural lake, perched 10 meters above the desert floor on sinter deposits, which is fed almost exclusively by thermal groundwater.

Borax Lake Population abundance estimates obtained in 1986-1996 indicated a fluctuating population ranging from approximately 4,100 and 37,000 fish. Recent estimates have ranged between approximately 8,200 and 25,500 chub (Figure 1). The basis for the Borax Lake chub's listed status was not population size, but the security of a very limited, unique, isolated, and vulnerable habitat. Aging data suggests that the Borax Lake chub population consists primarily of age 1 fish, with few age 2 and older fish present. Because Borax Lake chub are only found in one location and the population is apparently dominated by a single year-class of adults, the species has a high inherent risk of extinction.

Figure 1.  Borax Lake chub population abundance estimates from 1986 through 1997 and from 2005 through 2010.  Horizontal bars represent 95% confidence limits.  In 1986-1990 (solid symbols), only the perimeter of the lake was trapped.  After 1990 (open symbols), the entire lake was trapped.  Estimates are not directly comparable across these time periods.

Numerous recovery measures implemented since listing have improved the conservation status of Borax Lake chub and protection of its habitat. When the species was listed, critical habitat was designated on 259 hectares of land surrounding the lake, including 129 hectares of public lands and two 65-hectare parcels of private land. In 1983, the U.S. Bureau of Land Management designated the public land as an Area of Critical Environmental Concern.  The Nature Conservancy began leasing the private lands in 1983 and purchased them in 1993, bringing the entire critical habitat into public or conservation ownership.  The Nature Conservancy ended water diversion from the lake for irrigation and livestock grazing within the critical habitat. Passage of the Steens Mountain Cooperative Management and Protection Act of 2000 removed the public BLM lands from mineral and geothermal development within a majority of the basin. In addition, detailed studies of the chub and theri habitat have added substantially to our knowledge of basic Borax chub biology and the Borax Lake ecosystem. However, three primary threats remain.  These include the threat to the fragile lake shoreline, wetlands, and soils from a recent increase in recreational use around the lake (particularly off-road vehicle usage), the threat of introduction of nonnative species, and potential negative impacts to the aquifer from geothermal groundwater withdrawal if groundwater pumping were to occur on private lands outside the protected areas. This potential threat resurfaced in 2009, when Pueblo Valley Geothermal proposed a geothermal enery project on private property within 5 km of Borax Lake.

Annual Reports and Publications:

Scheerer, P. D., B. L. Bangs, S. Clements, and J. T. Peterson. 2012. 2012 Borax Lake chub investigations. USFWS contract 13420-08-J814 and BLM contract L10AC20301, Annual Progress Report, Corvallis.

Scheerer, P. D. and B.L. Bangs. 2011. 2011 Borax Lake Chub Investigations. Oregon Department of Fish and Wildlife, USFWS contract 13420-08-J814, and BLM contract L07PX02726, Annual Progress Report, Salem.

Scheerer, P. D. and S. E. Jacobs. 2010. 2010 Borax Lake Chub Investigations. Oregon Department of Fish and Wildlife, USFWS contract 13420-08-J814, and BLM contract L07PX02726, Annual Progress Report, Salem.

Scheerer, P. D. and S. E. Jacobs. 2009. 2009 Borax Lake Chub Investigations. Oregon Department of Fish and Wildlife, USFWS contract 13420-08-J814, and BLM contract L07PX02726, Annual Progress Report, Salem.

Scheerer, P. D. and S. E. Jacobs. 2008. 2008 Borax Lake Chub Investigations. Oregon Department of Fish and Wildlife, USFWS contract 13420-08-J814, Annual Progress Report, Salem.

Scheerer, P. D. and S. E. Jacobs. 2007. 2007 Borax Lake Chub Investigations. , Fish Research Project E-2-41, USFWS contract 134206M085, and BLM contract HAP074439, Annual Progress Report, Corvallis.

Scheerer, P. D. and S. E. Jacobs. 2006. 2006 Borax Lake Chub Investigations. Oregon Department of Fish and Wildlife, Fish Research Projects E-2-40, E-2-40 Supplement, and The Nature Conservancy, Annual Progress Report, Corvallis.

Scheerer, P.D. and S.E. Jacobs. 2005. Borax Lake Chub population assessment and monitoring strategy.  Oregon Department of Fish and Wildlife, Fish Research Project 134204M129 Annual Progress Report, Corvallis.

 

 

Send comments or questions regarding this webpage to  Shaun.Clements@oregonstate.edu