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Document Type

Thesis - University Access Only

Award Date

2008

Degree Name

Master of Science (MS)

Department

Wildlife and Fisheries Science

First Advisor

Steven R. Chipps

Keywords

fishes, diet, health, largemouth bass, feeding history

Abstract

Metabolism is a key component in fish energy budgets. Although primarily influenced by mass and water temperature, other factors are known to influence standard metabolic rate of fishes. Factors such as salinity, stress, water toxicity (e.g., heavy metals), diel periodicity, and stock differences can have positive and/or negative effects on oxygen consumption in fishes. Although they can be significant, these effects are generally not incorporated into fish bioenergetics models (BEM) to estimate metabolism. As a result, the accuracy of bioenergetics models can be hampered because of incomplete parameterization of the model. Moreover, efforts to synthesize information about factors affecting fish metabolism are lacking. To address this issue, I conducted a literature review to evaluate factors affecting fish metabolism. Results of this synthesis showed that environmental factors such as hypoxia, salinity, toxicity, and pH can influence metabolic rates in fishes, resulting in a -60% to +120% change in standard metabolic rate. Similarly, biological factors such as stress, stock differences, seasonal effects, and daily biorhythms can significantly influence standard metabolic rate in fishes. Incorporating environmental factors (e.g. hypoxia) into estimates of fish metabolism would improve the accuracy of energy budget calculations. Moreover, because of their potential to influence metabolism across a broad array of taxa, biological factors (e.g. seasonal variation) need to be considered in the development of fish energy budgets. Despite the popularity of bioenergetics models (BEMs), efforts to evaluate the accuracy of their predictions are often met with mixed success. Indeed, accuracy of BEM estimates varies with feeding rate of fishes and may be associated with error in measuring fish metabolism. Metabolic rate of fishes is a key parameter in energy budget formulations and can strongly influence accuracy of model predictions. In this study, I tested the hypothesis that metabolic rate of age-1 largemouth bass [mean (SE) = 105.9g (1.77); n = 24] varies with feeding history. Different feeding regimes were applied to two size classes of fish—i.e., maintenance rations for larger fish and ad libitum rations for smaller fish—over a nine week period such that body mass was similar prior to metabolic measurements. Fish that were fed maintenance rations had metabolic rates that were only 63% of those fed ad libitum (0.00230 vs. 0.00368 g O2/g/d). The percent difference between predicted versus observed food consumption for fish fed ad libitum was moderate (11%) indicating that the bioenergetics model provided a reasonable fit to observed values. For fish fed maintenance rations, differences between predicted and observed consumption values were significant and the error in the model was substantial (43%). After reducing the respiration parameter in the model by 37% (an experimentally determined amount), the percent difference dropped to 15%, suggesting that metabolism was overestimated for fish fed maintenance rations. These findings explain consumption-dependent error in the largemouth bass bioenergetics model and highlight the importance of feeding history in parameterizing fish metabolism. Incorporating feeding history into sub-models for metabolism in BEMs will improve their predicative accuracy and allow fisheries biologists to make better decisions regarding fish populations.

Library of Congress Subject Headings

Fishes -- Metabolism
Fishes -- Feeding and feeds
Largemouth bass -- Metabolism

Description

Includes bibliographical references (page 63-86)

Format

application/pdf

Number of Pages

98

Publisher

South Dakota State University

Rights

Copyright © 2008 Steven H. Ranney. All rights reserved.

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