Movement of non-native rainbow trout in an estuary with periodic summer hypoxia

Many present-day aquatic ecosystems are defined by anthropogenic activities such as the introduction of non-native species, habitat loss, and eutrophication. On Prince Edward Island, Canada, non-native rainbow trout (Oncorhynchus mykiss) have established in highly agricultural coastal watersheds. We used acoustic telemetry with continual oxygen and temperature monitoring to explore the relationship between rainbow trout movements, low dissolved oxygen, high temperature, and other environmental parameters in the eutrophic Dunk River estuary. We tested the hypothesis that rainbow trout capitalize on increased productivity from nutrient stimulation but face a trade-off with disturbed water quality. We divided the salinity transition gradient into zones representing the transition from freshwater to seawater and established that temperature and hypoxia increased with salinity. During hypoxic periods, movements decreased, and residence increased in low salinity habitat ( 6 mg L−1, discharge averaging 2 m3 s−1, and temperatures below 23 °C. This study provides insights into the success of rainbow trout in eutrophic estuaries.