Date of Award:

5-2009

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Watershed Sciences

Committee Chair(s)

Phaedra E. Budy

Committee

Phaedra E. Budy

Committee

Edward W. Evans

Committee

Matthew E. Baker

Abstract

Capturing the range of fish consumption and growth potential of large, heterogeneous lentic systems can be challenging due to strong gradients in productivity, the diversity of habits types present, and in some cases, site-specific water quality issues. Cutler Reservoir (Utah, USA) displays a high degree of spatial and temporal variation in physical conditions and potential water quality limitations for fish, including high summertime water temperature and large, diel fluctuations in dissolved oxygen concentrations. The combination of bioenergetics modeling and GIS spatial analysis offers a promising interface for quantifying the fish consumptive and growth potential across a spatially and temporally heterogeneous system like Cutler Reservoir, as well as identifying the role of potential water quality impairment on fish population abundance and condition. Within a bioenergetics framework, we combined empirical field estimates of fish growth and diet composition with a novel use of Thermal Remote Imaging (TIR) as a measure of spatially explicit thermal regime across a very large spatial scale (9,601,200 m2). We used these data inputs and a Geographic Information System (GIS) to generate spatially explicit, high-resolution maps of the growth potential of the primary sport fishes of Cutler Reservoir across spring, summer, and autumn seasons. The predicted growth potential of these fishes varied widely according to spatial and temporal differences in temperature and food availability, acting in concert with species-specific physiological tolerances and habitat preferences. Walleye (Sander vitreus) and black crappie (Pomoxis nigromaculatus) experience high growth potential throughout much of the reservoir during spring and fall, but are constrained to small thermal refugia during the heat of the summer. In contrast, channel catfish (Ictalurus punctatus) growth potential is low during spring and fall, but peaks strongly during the warm summer period. The proportion of habitat suitable for each primary sport fish ranged from highs of > 90% for channel catfish for most of the summer season to lows < 5% for crappie in July. Our approach provides a useful tool for analyzing factors that control fish growth in complex water bodies such as Cutler Reservoir as well as identifying the role of water quality in structuring fish community composition.

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