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Keywords

nitrogen, phosphorus, channel catfish

Abstract

Evaluating abiotic environmental factors that influence growth of sportfish is key to understanding population dynamics and making appropriate management decisions. This is especially true in river systems where primary and secondary productivity can vary across temporal and spatial scales. In this study, we assessed fish responses to ambient nutrient levels (total nitrogen and total phosphorus) using growth rates determined from age-1 Channel Catfish, Ictalurus punctatus, in Platte River, Nebraska. Water quality and growth data were collected from sites across the central and lower Platte River from 2007 to 2013. We analyzed Platte River water quality data to find yearly average levels of total nitrogen and phosphorus in the system. Results show a significant difference in growth rates and nutrients levels across Platte River segments, however nutrient levels did not help explain the differences in growth. For example, the mean growth rate across years was not significant between central and lower river segments (p-value = 0.202), but the mean total nitrogen and total phosphorus levels were significantly greater in the lower river segment across all years (p = 0.004 for nitrogen and p = 2.028-6 for phosphorus). While this study lacks evidence for a clear correlation between nutrient levels and Channel Catfish growth future investigations could help clarify the short-term and long-term impacts of eutrophication of rivers such as the Platte River that run through agricultural and urban landscpaes.

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