Vulnerability Index to Scale Effects of Offshore Renewable Energy on Marine Mammals and Sea Turtles Off the U.S. West Coast (VIMMS)

Abstract

With proven advances in offshore energy technology, the ambitious objectives of the U.S. Federal government, and a host of planning and preparation at the state and local levels, there is increasing interest and progress in developing sustainable offshore alternative energy. This includes broad scale implementation of offshore wind energy development and focused implementation of hydrokinetic energy systems harnessing the power of waves and tides. These technologies and their implementation in different areas are being extended, applied, and in some cases substantially modified from earlier developments in other parts of the world, notably Europe. On the U.S. East Coast this is largely taking the form of large wind farms with monopile structures in relatively shallow water. Many lease areas for such wind farms have already been sold and large-scale construction is soon to be underway. For the U.S. West Coast however, the vastly different bathymetry associated with being an active geological margin favors and requires quite different types of industrial developments for transforming the power of offshore wind into electrical energy. Conditions also offer varied and unique opportunities to convert the power of waves and tides into clean and sustainable electrical energy.

Given the novel and nascent nature of these technologies and contexts for industrial developments of offshore sustainable energy, there is considerable uncertainty regarding potential environmental impacts. There have now been several decades of relatively intensive monitoring and impact assessment of myriad issues regarding offshore wind developments in Europe, above and below water for avian and marine taxa. However, the contexts, species, and ecological systems differ substantially from those that will be exposed to offshore sustainable energy in the U.S. More recently, baseline monitoring, modeling, and early stages of evaluating potential impacts, both positive and negative, have been initiated on the U.S. East Coast focused largely on offshore wind with generally similar types of industrial development but a much wider range of species. These include low-frequency sound sensitive species that would be expected to be more susceptible to disturbance from associated low frequency noise, notably baleen whales. Further behind still in the development and deployment of wind and hydrokinetic energy developments is the U.S. West Coast, affording yet another set of unique challenges from both industrial (e.g., floating offshore wind in very deep water) and ecological perspectives (e.g., additional species previously unstudied in terms of impact assessment).

It is early in the development and impact assessment of offshore sustainable energy off the U.S. West Coast. There are myriad acknowledged uncertainties regarding aspects of developments, species that may be exposed to potential impacts, and what those impacts may be. However, the first offshore lease sales in California have already occurred, with designated lease areas off Morro Bay and the Humboldt coast. There are already proven offshore wave energy pilot installations off Oregon. Put simply, we are in the early stages of the deployment of these technologies in most areas off the U.S. West Coast, and we clearly need analytical tools to (1) evaluate potential susceptibility to impacts of disturbance, injury, or mortality, and (2) systematically identify data gaps, research needs, and monitoring and mitigation priorities.

Building on an iterative development of novel relativistic risk assessment methods to evaluate the potential impacts of human disturbance of marine mammals (Ellison et al. 2012; Wood et al. 2012; Southall et al. 2018; 2019; 2021a; 2021b; 2023), an interdisciplinary team of biologists and researchers involved in the current study adapted aspects of this approach to a new setting. While these approaches were relatively novel in their application to behavioral and auditory disturbance of protected marine mammals from offshore industrial activity, similar kinds of semi-quantitative, expert elicitation-based risk assessment methods have been applied in an increasing diversity of contexts. Examples include assessments of marine fisheries management (e.g., Morrison et al. 2015; Johnson et al. 2016), collision and displacement for seabirds associated with offshore wind energy development (Adams et al. 2017), and evaluations of impacts on marine mammals from climate change (Albouy et al. 2020) and disease (Norman et al. 2022).

Most of these earlier assessments focused on specified types, contexts, and strategically selected spatial and temporal patterns of industrial development based on realistic operations, the nature, timing, precise location, and other features of offshore development for this West Coast focused effort were not deliberately specified. Consequently, the objective here was to apply and adapt aspects of earlier risk assessment methods used to consider impacts of seismic surveys and large piling-based wind farms (notably Southall et al. 2023) to evaluate the relative vulnerability of many protected marine species on the U.S. West Coast to disturbance associated with all forms of offshore alternative energy development. The fundamental approach retains the species-specific, spatially- and temporally explicit nature of the earlier risk assessment but focuses, as an initial step, on just the species-specific vulnerability to the kinds of anticipated disturbances based on a structured host of factors. Subsequent analyses are needed, as discussed, to evaluate specific and finer spatial and temporal aspects of exposure magnitude and severity.

The geographic scope is very broad, extending from Point Conception, CA to the U.S.-Canada border off Washington, and coastal (not inshore) to oceanic waters (out to 2,500 m water depth). Specified geographical latitudinal zones and depth regimes with identified through an expert group elicitation process based on both human-centric (e.g., borders) and ecological considerations. Risk assessment methods as applied here for West Coast species also represents the first consideration of non-marine mammal species in this overall effort, specifically Endangered Species Act (ESA)-listed sea turtle species. Further, central to the approach taken in this novel context for the California Current Ecosystem where ecological patterns are so intimately tied with wind-driven upwelling was the designation of oceanographic “seasons” rather than traditional calendar-based ones. What was achieved through this adaptation and a concentrated and structured assessment process involving many subject matter experts and biologists was a systematic assessment of potential vulnerability of all marine mammal and sea turtle species to disturbance in defined geographical areas and oceanographic “seasons” using a structured assessment with population, life history, acoustic, and other environmental factors.

A core team of experts that was centrally involved in developing the earlier risk assessment methods (namely the authors of Southall et al. 2023) partnered with colleagues from an experienced and centrally engaged conservation organization (California Marine Sanctuary Foundation (CMSF)) to convene a series of workshops engaging more than a dozen expert sea turtle and marine mammal biologists and researchers to conduct the vulnerability assessment. These experts, who were invited and engaged in the discussion to varying degrees based on their availability, are identified below. Their mention here does not necessarily imply their personal concurrence, or that of their affiliated employer, with every scoring assessment or conclusion presented below that was developed during the expert scoring process.

Elizabeth Becker (ManTech; NOAA affiliate)
Karin Forney (NOAA)
Elliott Hazen (NOAA)
Scott Benson (NOAA)
Dominic Tollit (SMRU, Consulting)
Jenn Amaral (Marine Acoustics Inc (MAI))
Kristin Reed (Upwell)
George Shillinger (Upwell)
Megan McKenna (SEA, Stanford University)
Daniel Pelacios (Oregon State University)
John Calambokidis (Cascadia Research)
Jeff Moore (NOAA) Shannon Rankin (NOAA)
William Ellison (MAI)
Chris Clark (Cornell University; MAI)

Two half-day virtual workshops (December 2021 and March 2022) were conducted ahead of the main vulnerability scoring exercise to present the existing vulnerability risk assessment methods, adapt them for this unique assessment, agree on the segregation of the study area and analysis periods, and consider potential species groupings. Through these group processes and interim discussions on key topics, the team concurred on the majority of these parameters and the assessment criteria, setting up the primary action for this project, namely a three-day in-person workshop held 7–9 June 2022 held at the Long Marine Laboratory at the University of California, Santa Cruz in Santa Cruz, CA. The results of the vulnerability scoring assessment and the synthesis conclusions and messages contained in this report were conveyed in a series of sequential virtual webinars conducted from January to March 2023 by the project team for the Bureau of Ocean Energy Management (BOEM), National Oceanic and Atmospheric Administration (NOAA), National Marine Fisheries Service, state scientific and management agencies in California, Oregon, and Washington, and representatives of Native American tribes.

This report summarizes the methods applied (section 2) in the vulnerability scoring process, including specified spatial zones, temporal windows, adapted scoring assessment criteria, species/stocks of marine mammals considered, and approaches to summarizing relative vulnerability (risk) assessments for each species/stock-area-season context. As described below, several different approaches were utilized to characterize and account for uncertainty both within the scoring process, as a separate qualitative assessment, and in gap analyses with specific research needs assessments. Vulnerability scoring results and relativistic risk assessments are then presented (for most but not all applicable combinations) both by species/stock for each zone (area) and season accordingly (section 3) and by zone for each season with relative scores across all species considered (section 4). A synthesis assessment of conclusions, data gaps, and recommended next steps follows (section 5). The raw data components of the vulnerability scores and ratings for each marine mammal and sea turtle species (or species stock) in this report are provided in spreadsheets in the following workbook files: