Comparing dissolved oxygen concentrations above and below the Capilano Fish Hatchery dam and the potential relevance to salmon

Abstract

Dissolved oxygen (DO) concentrations within aquatic habitats are crucial to the growth and development of salmon. It has been shown that bodies of water with increased turbulence have greater surface areas across which oxygen can diffuse. In this study, we investigated whether the presence of the Capilano Fish Hatchery dam altered DO concentrations through this model and explored the relevance of our findings to salmon. Measurements were collected using Vernier DO probes while simultaneously measuring pH and temperature using a pH sensor and thermometer to determine whether these factors were potentially influencing the DO measurements. The data indicates a significant difference between DO concentrations above and below the dam, with observed medians of 9.15±0.137 ppm and 9.90±0.193 ppm respectively, thus confirming our prediction of finding higher DO concentration below the dam. The null hypothesis that there is no difference in DO between sampling sites was rejected with p = 1.45E-11 < α (0.05). No statistical difference was found between the sampling sites for pH and temperature, nor was there any correlation found between these factors and DO, which further supports our results being due to changes in DO. The DO values at each site were found to be within the thresholds necessary for salmon survival, indicating suitable DO conditions for salmon at both sites. As hypoxic or hyperoxic conditions are detrimental to salmon health and survival, this field of research is promising for future investigations with respect to salmon welfare.