Unknown waters of the Uintah Basin: evaluating the limnology, morphometry, and fish communities of seven lentic waters on the Uintah and Ouray reservation, Utah
Authors: Stephen Klobucar, Phaedra Budy, Gary P. Thiede
Year: 2010 (xlii)
Abstract
Evaluating and understanding preexisting conditions of aquatic systems is essential to develop and implement efficient fisheries management strategies. In lentic systems, knowledge of basic limnology, morphometry, and fish community composition provides a baseline for management. The northern region of the Ute Indian Tribe’s Uintah and Ouray reservation in northeastern Utah contains seven rarely studied ponds and reservoirs that support a variety of sport fisheries, but for which little baseline information is known. We used a survey grade GPS and depth sounder to create bathymetric maps and standard limnological methods to examine temperature, dissolved oxygen, light extinction, primary production, zooplankton, benthic invertebrates, and total nutrients of each system. We sampled fish communities with experimental gill nets in the littoral zone. Area and volume of the waters varied greatly from <1 to 172 ha and 1.4x104 to 1.2x107 m3, respectively. These measurements varied temporally within some systems; one reservoir’s volume increased by 1.85x106 m3 across as little as two hours. Limnology and fish communities were also highly variable. Mid-summer secchi depths ranged among waters from 0.8 to 5.45 m while chlorophyll-a concentrations increased as much as 30-fold in one month. Cold water fish communities were depauperate including primarily rainbow trout, Oncorhynchus mykiss, and/or brown trout, Salmo trutta; these systems appear to be forage limited. Warm water communities included largemouth bass, Micropterus salmoides, and walleye, Sander vitreus, with some cold water species mixed in as well; while productive, these systems may be limited by water withdrawal and/or a large abundance of common carp, Cyprinus carpio. Based on our analyses, the seven waters can be classified into three general types: 1) warm water reservoirs and ponds that support complex food webs with moderate to high fish and macrophtye production 2) cold water reservoirs with moderately complex food webs and moderate fish production 3) cold water reservoirs and ponds with simple food webs, relatively low fish production and variable primary production. Our results will assist the Ute Tribe Fish and Wildlife Department in establishing an improved sampling protocol, a more cost and biologically efficient stocking program, and a better overall understanding of the waters on the Uintah and Ouray reservation. Future efforts will closely examine predator-prey interactions and limitations to fish growth within each system.