A Vulnerability Index to Scale Effects off Offshore Renewable Energy on Marine Mammals and Sea Turtles of the U.S. West Coast

Given the novel and nascent nature of the technologies and environmental contexts for industrial developments of offshore sustainable energy, there is considerable uncertainty regarding potential environmental impacts. While it is early in the development and impact assessment of offshore wind and hydrokinetic energy off the U.S. West Coast it is not premature to begin broad-scale assessments of the potential vulnerability of key species and to identify and fill key data gaps. This study adapted and applied a structured semi-quantitative assessment process involving many subject matter experts and biologists to systematically evaluate the potential vulnerability of all West Coast marine mammal and sea turtle species to disturbance from offshore energy in defined geographical areas and oceanographic "seasons" based on species, time, and area-specific population, life history, acoustic, and other environmental factors. Extensive variability in vulnerability was observed within and across species and area-time contexts considered. Certain species, notably those that were endangered, had decreasing population trends or low sample size, had either high site fidelity or concentrated periods of key behavior, and those most susceptible to direct physical impacts, generally had higher vulnerability scores, as intended that the scoring scheme would capture. We found relatively lower overall vulnerability in winter relative to upwelling and especially post-upwelling seasons and relatively lower vulnerability in oceanic depth regimes relative to slope and especially shelf zones. Additionally, higher vulnerability across species was found in high-density species habitat use areas that overlap with areas of high existing human presence (e.g., off Central California and Northern Washington). Strategic research and monitoring priorities based on data gaps and evaluated vulnerability were identified.

USD: $299,688

2021-08-04 → 2023-02-04