Communications: Tolerance of Rainbow Trout to Dissolved Oxygen Supplementation and a Yersinia ruckeri Challenge

Abstract

Dissolved oxygen accounted for a significant proportion of the variation in mortality rate of rainbow trout Oncorhynchus mykiss acclimated for 10 weeks to a range of dissolved oxygen levels and challenged with Yersinia ruckeri. Moderate levels of oxygen supersaturation (150%) resulted in greater cumulative mortality (17.9%) among fish exposed to a 0.5-h static bath challenge with Y. ruckeri (1 × 10⁷ colony-forming units/mL). In contrast, hypoxic (70%) and normoxic (100%) levels of dissolved oxygen resulted in 12.8% and 10% cumulative mortality. Higher oxygen levels provided no additional “protection” against infection by Y. ruckeri in this study.