Characterizing Sockeye Salmon Smolt Interactions with a Hydrokinetic Turbine in the Kvichak River, Alaska

Abstract

The development of hydrokinetic turbines has been motivated by the desire to reduce fossil fuel reliance, energy production costs, and greenhouse gas emissions. Detailed information about fish interactions with hydrokinetic turbines is limited; therefore, this study sought to characterize the interactions between a turbine (RivGen; Ocean Renewable Power Company) and Sockeye Salmon Oncorhynchus nerka from one of the most productive populations in the world-that in the Kvichak River, Alaska. By viewing real-time video imagery, our objectives were to quantify the number of Sockeye Salmon smolts that interacted with the turbine and to assess the behaviors/outcomes of these interactions during the species' smolt out-migration. From May 21 to June 10, 2021, a total of 2,374 Sockeye Salmon smolts passed through the field of view of cameras placed immediately downstream of the hydrokinetic turbine. The majority of these observed events occurred over a short (5-d) time period from late May to early June during periods of darkness (0000-0400 hours). Fish were observed passing through the hydrokinetic turbine in both normal and disoriented manners, with the rotational status/speed of the hydrokinetic turbine appearing to influence passage behavior. Blade strikes on fish were also observed, all of which occurred when the turbine was rotating at high "production" speeds. After temporally and spatially extrapolating the observed fish interactions to account for our subsampling, the results suggest that when monitoring was conducted, the hydrokinetic turbine interacted with approximately 200,000 Sockeye Salmon smolts during this species' smolt out-migration period. This study adds to the sparse knowledge base on fish interactions with emerging riverine hydrokinetic devices and may inform strategies to mitigate the impacts of developing energy projects on socially and culturally important fisheries.

Observing fish interactions with marine energy turbines using acoustic cameras

“…However, in some cases, sudden changes in fish orientation or trajectory may indicate collision (e.g. Courtney et al, 2022; Staines et al, 2022).…”

Quantifying conditional probabilities of fish-turbine encounters and impacts

“…We define collision as physical contact between an animal and the turbine base or a non-moving device component (e.g., Müller et al, 2023). We define blade strike as contact between an animal and a rotating blade (e.g., Castro-Santos and Haro, 2015;Courtney et al, 2022). In the model, collision and blade strike are treated as potential sequential events, where fish can collide with a turbine support structure and then be struck by a rotating blade.…”

“…Primary concerns include collisions with stationary turbine components and/or strikes from rotating blades that could inhibit growth or affect survival of fish, seabirds, or marine mammals (Hemery et al, 2021). Knowledge gaps and inadequate empirical data on animal-device interactions necessitate obtaining, quantifying, and interpreting physical and biological data that can be used to discern the influence of animal-turbine encounters (e.g., Copping and Hemery, 2020), collisions (e.g., Müller et al, 2023), and blade strikes (e.g., Castro-Santos and Haro, 2015;Courtney et al, 2022). Unverified perceptions of mortality from animaldevice interactions can impede development of monitoring regulations for tidal turbine sites.…”

“…Encounter and collision rates between aquatic animals and tidal turbines are not well quantified due to limited opportunities and appropriate technologies to observe, measure, and characterize interactions (Fox et al, 2018;Courtney et al, 2022;Bender et al, 2023). Worldwide, there have been few (Copping et al, 2021) acoustic and optical technologies deployed to monitor tidal energy sites (e.g., Williamson et al, 2017;Staines et al, 2022).…”

“…Collision with stationary components of a device is another factor that is not commonly separated from blade strikes in published models. Collisions with stationary structures (Müller et al, 2023) could disorient fish (Courtney et al, 2022) and potentially lead to a blade strike.…”