Name: Megan T. Wyman
Currently, there is large-scale interest in developing marine-based energy sources and extensive subsea power cable networks. Despite growing concern that local perturbations in the magnetic field produced by current passing through these cables may negatively affect electromagnetically sensitive marine species, e.g., disrupted migration; few studies have examined free-living animals. We used acoustic biotelemetry tracking data to examine movement behaviors and migration success of a magneto-sensitive fish, late-fall run Chinook (LFC) salmon (Oncorhynchus tshawytscha), in relation to the energization of a magnetic field-producing subsea power cable, as well as other potentially influential environmental parameters. We analyzed detection records of tagged LFC salmon smolts during their out-migration through the San Francisco Bay before and after the installation of an 85-km high-voltage direct-current transmission cable. Cable energization did not significantly impact the proportion of fish that successfully migrated through the bay or the probability of successful migration. However, after cable energization, higher proportions of fish crossed the cable location and fish were more likely to be detected south of their normal migration route. Transit times through some regions were reduced during cable activity, but other environmental factors were more influential. Resource selection models indicated that proximity to the active cable varied by location: migration paths moved closer to the cable at some locations, but further away at others. Overall, cable activity appeared to have mixed, but limited effects on movements and migration success of smolts. Additional studies are recommended to further investigate impacts of subsea cables on fish migrations, including potential long-term consequences.
This study was funded by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, award no. DE-EE0006382 and by the US Department of the Interior, Bureau of Ocean Energy Management, Environmental Studies Program, Washington, DC, through Interagency Agreement Number M14PG00012. It was funded through a cost share agreement with the Electric Power Research Institute (Project 1–105902).
- To investigate whether fish movement behaviors were affected by the energization of the cable,
- Whether the energization of the cable hindered or facilitated outward migration of LFC smolts
Overall, cable activity appeared to have mixed effects on migration behavior of LFC smolts in the SF Bay. In some cases, cable activity appeared to be a possible attractant for smolts as cable activity increased the probability that fish were detected at Bay Bridge, located along the path of the cable to the south of the normal migration route from the delta to the Pacific Ocean. Furthermore, migration paths in San Pablo Bay (as taken from first detection site ‘snapshots’) were closer to the cable location when the cable was active. However, fish were found further away from the cable at Benicia Bridge after it was active. Taken together, these results indicate that cable energization may affect some migration behaviors of LFC smolts, but does not appear to have a large adverse or beneficial direct impact on the overall survival of fish through the San Francisco Bay. The relationships between migration behaviors and cable activity, as well as other predictive factors, can vary between study locations, likely due to differences in the physical and hydrodynamic characteristics of each site.
Wyman, M.; Klimley, A.; Battleson, R.; Agosta, T.; Chapman, E.; Haverkamp, P.; Pagel, M.; Kavet, R. (2018). Behavioral responses by migrating juvenile salmonids to a subsea high-voltage DC power cable. Marine Biology, 165, 1-15.