Performance and Oxygen Consumption of Snake River Cutthroat Trout Reared at Four Densities with Supplemental Oxygen

Abstract

Abstract Snake River cutthroat trout (Oncorhynchus clarki) of the Bar BC strain were reared at four densities in triplicate for 18 weeks. Supplemental oxygen was required in the rearing units holding the three highest densities to maintain adequate dissolved oxygen (DO) levels of 6–7 ppm (61–71% of saturation) after the last feeding in the afternoon. Density indices (lb!ft3 per inch of fish length) achieved for each treatment averaged 0.48, 1.40, 2.12, and 2.30, and fish density averaged 3.43, 10.56, 15.56, and 15.42 lb/ft3, respectively, at the conclusion of the study. Survival, weight gain, feed conversion, and fish health were adversely effected by increased density; however, dorsal and pectoral fin condition, total length, length variation, and water quality were not adversely effected. Neither un-ionized ammonia (maximum, 0.0051 ppm) nor total carbon dioxide (maximum, 24.2 ppm, pH 7.5) concentrations reached detrimental levels. Over a 24-h period at the end of the study, daily DO consumption averaged...