Water Resources Professional Project Reports


Barry Weinstock

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The purpose of fish population studies is to better understand the functional relations between life stages, abundances, and spatial distributions of fish populations in the upper Rio Grande and its tributaries. Taos Field Office, New Mexico, has managed an electrofishing fish population program since 2004 for seven reaches of the Rio Grande. Managers are interested in actual angler catches and satisfaction, and often use angler surveys to gather this data. This project compared two methods of gathering data about fish populations; electrofishing and angler questionnaires. Both have deficiencies in that they collect different types of data. The intent is to explore the utility of mixed method analysis for obtaining information regarding fish populations. Significantly larger sample sizes are necessary for the angler survey to be evaluated statistically. This study performed 39 surveys that provided 52 responses. Approximately 400 responses would be required for statistical significance. This project found that angler surveys can be used as a valuable supplement but not a replacement for, electrofishing data. In particular, angler surveys provide information on: 1. Historic knowledge of the resource. 2. As tools for identifying environmental conditions that affect the resource. 3. As tools for understanding stakeholder satisfaction. 4. Stakeholder engagement creates a sense of stewardship for the participant and opportunity for the manager to increase their understanding of the resource with anglers 'wisdom'. Combining the two methods has additional utility for fisheries study, even at the scale accomplished here. For example, the survey revealed what percent of anglers target trout in the Racecourse, and that those anglers experienced a decrease in the number and size of fish caught. With the assumption that anglers vi enjoy catching more, and larger fish, survey results may be interpreted as a measure of satisfaction. Between 2004 and 2014, electrofishing results showed that trout species in the Orilla Verde have declined in numbers, and size class has shown little change. Smallmouth bass have increased from 4% of an electrofishing catch to 45%. The Racecourse data show that Rainbow trout numbers have remained steady with an increase in size class. Brown trout stocking ceased in 2010, however, Brown trout data show that spawning is maintaining a population. Overall trout populations have declined. Smallmouth bass have increased from 3% of an electrofishing catch to 33%. The Middle Box comparison of trout population between 2005 and 2008 showed that trout numbers and sizes decreased. There was concurrence between electrofishing and angler survey in identifying general trends about the Orilla Verde trout and bass population numbers and size of fish. The Racecourse results showed anglers in less strong agreement with electrofishing results. For the Middle Box, professional angler's observations concurred with electrofishing data, while less experienced angler's responses varied.

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electrofishing fish population program, angler


A Professional Project Report submitted in partial fulfillment of the requirements for the degrees of Master of Water Resources, Water Resources Program and Master Community and Regional Planning, School of Architecture and Planning, at the University of New Mexico.