Hydroacoustic Assessment of Behavioral Responses by Fish Passing Near an Operating Tidal Turbine in the East River, New York

Abstract

An important environmental issue facing the marine and hydrokinetic energy industry is whether fish that encounter underwater energy devices are likely to be struck and injured by moving components, primarily rotating turbine blades. The automated analysis of nearly 3 weeks of multibeam hydroacoustics data identified about 35,000 tracks of fish passing a tidal turbine in the East River, New York. These tracks included both individual fish and schools during periods with the turbine absent, the turbine present and operating, and the turbine present but not operating. The density of fish in the sampled area when the turbine was absent was roughly twice the density observed when the turbine was in place, particularly when the turbine was operating. This suggests that some avoidance occurred before fish were close enough to the turbine to be observed by the hydroacoustics system. Various measures of swimming behavior (direction, velocity, and linearity) were calculated for each track and evaluated for indication of behavioral responses to turbine presence and operation. Fish tracks were grouped based on tidal cycle, current velocity, and swimming direction and were evaluated with respect to turbine presence and operation and with respect to distance from the turbine. Nonparametric tests (Kolmogorov–Smirnov test) and multivariate analysis (canonical discriminant analysis) found significant differences among groups with respect to turbine presence and operation, suggesting that some fish responded to the turbine by adjusting swimming behavior, such as making small adjustments to swimming direction and velocity as they passed near the turbine. We found no evidence that fish were being struck by rotating blades, but there did appear to be large‐scale avoidance initiated out of the range of the hydroacoustics detection system. More study is needed to determine whether such avoidance behavior has significant ramifications for normal fish movement patterns, bioenergetics, seasonal migrations, and predator exposure. Received October 28, 2016; accepted May 29, 2017 Published online August 2, 2017

Long‐term effect of a tidal, hydroelectric propeller turbine on the populations of three anadromous fish species

“…We are not discussing other hydrokinetic devices. Although instream propeller turbines are not associated with a barrage or causeway and fishes are thought to have greater probability of avoidance (Viehman & Zydlewski, ; Shen et al, ; Bevelhimer et al, ). The probability of turbine encounter in the open ocean depends on numerous conditions such as the number and distribution of turbines, turbine size, probability of behavioral avoidance, benthic or pelagic species relative to turbine position in the water column, year, month and tidal stage (Shen et al, ).…”

“…This was possible because the Annapolis River has a small estuary surrounded by people. In Minas Passage and at other instream turbine sites the pre‐operational environment and the effects of test turbines on fishes are being studied (Tollit et al, 2011; Redden et al, ; Lewis et al, ; Bevelhimer et al, ) but the remoteness, depth and properties of the physical environment makes environmental monitoring difficult (Sanderson & Redden, ; FORCE, ). The effects of instream propeller turbines will be difficult to observe and may not be obvious until too late to reverse.…”

“…These resources sustain the economic viability of many coastal communities and their loss will affect the livelihoods of their human populations (Dadswell & Rulifson, 1994;Gill, 2005). Because the instream propeller turbines operate without a barrage the chance of fish encounters are considered to be reduced (Shen et al, 2016;Bevelhimer et al, 2017), however, because of their size and the fact most operate on both ebb and flood tide means they will pass huge amounts of water through their draft tube (c. 1,200 m 3 s −1 for a 16 m diameter machine; FORCE, 2017) potentially affecting large numbers of fishes and capable of impacting cetaceans (Tollit et al, 2011;Hammer et al, 2015). Is it wise and justifiable to replace one renewable resource with another when alternate forms of electric generation are possible?…”

Changes in Relative Fish Density Around a Deployed Tidal Turbine during on-Water Activities

“…The early stages of this industry and the difficulty of surveying fishes in these energetic environments necessitate empirical data. While there have been several peer-reviewed field studies in recent years that have decreased uncertainty in this area [11][12][13][14][15][16][17], many questions remain. Best practices for monitoring and detecting device effects, at the individual or array level, remain under development [18].…”

“…The near-field evasion zone (0-5 m or <2 turbine diameters from a device, mesoscale) and mid-field avoidance zone (5-100 m or >2 turbine diameters from a device, macroscale) have been proposed as the most important for assessing fish interactions with a single device [4,19]. Near-field observations have been few to date [11,13,[15][16][17] and reflect the difficulty of observation near an operating device. Mid-field effects of a deployed device on fish, if any, could involve behavior changes related to general avoidance associated with optimizing swimming speed while minimizing energetic costs [20,21].…”