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<br />Transactions of the American. Fisheries Society 134:960-974, 2005 [.dlxtlCle?
<br />® Copyright by the American Fisheries Society 2005
<br />DOI: 10.1577/x04-090.1
<br />Development of a Bioenergetics Model for Humpback Chub and
<br />Evaluation of Water Temperature Changes in the Grand
<br />Canyon, Colorado River
<br />JAMES H. PETERSEN*
<br />U.S. Geological Survey, Western Fisheries Research Center, Columbia River Research
<br />Laboratory, 5501 Cook-Underwood Road, Cook, Washington 98605, USA
<br />CRAIG P. PAUKERTI
<br />U.S. Geological Survey, Southwest Biological Science Center, Grand Canyon Monitoring and
<br />Research Center, 2255 North Gemini Drive, Flagstaff, Arizona 86001, USA
<br />Abstract.-The construction of Glen Canyon Dam above the Grand Canyon (Arizona) has reduced
<br />the water temperature in the Colorado River and altered the growth rate and feeding patterns of
<br />the federally endangered humpback chub Gila cypha. A bioenergetics model for humpback chub
<br />was developed and used to examine how warmer water temperatures in the lower Colorado River
<br />(achieved through a temperature control device [TCD], at Glen Canyon Dam) might influence their
<br />growth rate and food requirements. Parameter values for humpback chub were developed by Monte
<br />F Carlo filtering and fitting to laboratory growth. Parameter bounds were established from the lit-
<br />erature for Gila species, random parameter sets were selected within these bounds, and the growth
<br />of modeled humpback chub was compared with criteria from a laboratory growth experiment at
<br />24°C. This method of parameter estimation could be applied to other imperiled fishes where
<br />',l? physiological studies are impractical. Final parameter values were corroborated by comparison
<br />with the growth rates of humpback chub from independent field and laboratory studies. Simulations
<br />indicated that increasing water temperatures from approximately 9°C to 16°C during summer and
<br />fall, the change expected from the TCD, may have a minimal effect on humpback chub growth
<br />l rate unless food availability also increases with temperature. To evaluate the effects of increased
<br />temperatures on humpback chub in the lower Colorado River, it will be essential to monitor their
<br />growth rate, the invertebrate community, and the predators of humpback chub, which are also
<br />influenced by temperature changes. Bioenergetics models for humpback chub and their predators
<br />should be helpful tools for identifying potential scenarios and evaluating the complex interactions
<br />z resulting from a TCD.
<br />The native fish community in the southwestern
<br />United States has changed dramatically over the
<br />last 100 years because of watercourse changes,
<br />introduction of nonnative species, destruction of
<br />spawning habitat, and degraded water quality
<br />(Minckley and Deacon 1991; Mueller and Marsh
<br />2002). Humpback chub Gila cypha is native in the
<br />Colorado River Basin and has been listed as a
<br />federally endangered species since 1967 (USFWS
<br />2002). Humpback chub is a large cyprinid that
<br />reaches a maximum size of about 480 mm and 1.2
<br />kg. One of the largest populations of humpback
<br />chub occurs in the Colorado River in Grand Can-
<br />Corresponding author: jim-petersen@usgs.gov
<br />t Present address: U.S. Geological Survey, Kansas
<br />Cooperative Fish and Wildlife Research Unit, Division
<br />of Biology, Kansas State University, 205 Leasure Hall,
<br />Manhattan, Kansas 66506, USA.
<br />Received May 28, 2004; accepted March 14, 2005
<br />Published online June 22, 2005
<br />yon below Glen Canyon Dam (USFWS 2002).
<br />Smaller populations occur above Glen Canyon
<br />Dam in the upper Colorado River, in Green River,
<br />and in Yampa River (USFWS 1990; Douglas and
<br />Marsh 1996; USFWS 2002).
<br />Plans to facilitate the recovery of humpback
<br />chub populations have been developed and were
<br />recently revised by the U.S. Fish and Wildlife Ser-
<br />vice (USFWS 2002). These plans include specific
<br />alternatives for "downlisting" and "delisting" the
<br />species, assuming there are improvements in adult
<br />numbers, better recruitment of age-3 fish, at least
<br />three viable populations, and removal or minimi-
<br />zation of specific threats (USFWS 2002). The most
<br />serious threats to the recovery of the Grand Can-
<br />yon population include streamflow and tempera-
<br />ture modifications caused by Glen Canyon Dam,
<br />parasitism, competition with nonnative fishes, and
<br />predation by nonnative species, especially rainbow
<br />trout Oncorhynchus mykiss and brown trout Salmo
<br />trutta (USFWS 1990, 2002).
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