There is significant interest in the interaction of aquatic organisms with current-based marine and hydrokinetic (MHK) technologies. Determining the potential impacts of MHK devices on fish behavior is critical to addressing the environmental concerns that could act as barriers to the permitting and deployment of MHK devices. To address these concerns, we use field monitoring and fish behavior models to characterize the behavioral responses of fish to MHK turbines and infer potential stimuli that may have elicited the observed behavioral changes.
Monitoring fish interactions with hydrokinetic turbines allows one to consider the magnitude and ecological significance of several potential behavioral risks that have been identified for tidal turbines including the disruption of migratory behavior and food acquisition (Boehlert and Gill, 2010; Frid et al. 2011), behavioral attraction to the device (Boehlert and Gill, 2010; Frid et al. 2011), and avoidance of preferred habitat occupied by the device (Boehlert and Gill, 2010; Polagye et al. 2010; Hammar et al. 2013; Broadhurst et al. 2014). These risks can be assumed to be minimal if the observed fish movement patterns suggest the turbine has only small and temporary effects on normal swimming patterns or fish distribution within a channel.
Blade strike has also been identified as a primary concern associated with the operation of tidal turbines (U.S. Department of Energy, 2009). There have been multiple blade strike studies conducted in laboratory settings using fish exposed to turbines in a confined channel. While these studies indicate fish can avoid blade strike if they swim through a turbine, they do not address what proportion of fish will avoid the turbine completely while swimming through a natural channel. This question is critical in assessing the actual risk of blade strike (Hammar et al. 2015). Earlier work in our study area (Viehman and Zydlewski, 2014) partially addressed this data gap using dual-frequency identification sonar (DIDSON) monitoring of fish movement within a few meters of the Ocean Renewable Power Company (ORPC) turbine generating unit (TGU). The work described in this report further expands the spatial scale of analysis by using field surveys, hydrodynamic modeling, and behavioral simulations that cover fish response to the turbine hundreds of meters upstream and downstream.
The overall goal of this project was to monitor fish movements around an ORPC TGU, use the data to characterize the magnitude and ecological significance of behavioral responses, and investigate the potential variables driving the observed behavioral responses. This multi-year project spanning fiscal years (FYs) 2013–2016 was a collaboration between Principal Investigator Mark Grippo (Argonne National Laboratory), Dr. Andrew Goodwin (U.S. Army Engineer Research and Development Center), Dr. Gayle Zydlewski (University of Maine), and Prof. Huijie Xue (University of Maine). This report describes our activities to (1) collect hydroacoustic fish survey data, (2) produce high-resolution simulated flows for Cobscook Bay for the survey period, and (3) examine whether fish responded to visual and auditory stimuli generated by the turbine as well as natural and turbine-related changes in flows within the channel.