The rapid expansion of offshore wind farms (OWF) provides a growing source of renewable energy but requires careful planning to limit impacts on other ocean uses, including commercial fishing. OWF development often results in the exclusion of fishing activity from within and around the wind energy area. This can displace fishing vessels from productive grounds, potentially forcing them to travel farther, target less valuable species, or simply fish less. But closures can also serve as de facto marine protected areas, allowing fish stocks to rebuild and spill over into adjacent waters, potentially partially or fully offsetting potential losses. Whether the net effect is positive or negative depends on several factors, including fisher behavior, stock status, and species biological characteristics. This is not obvious from historical fishing footprints alone.
Our team at the Environmental Markets (emLab) at the University of California, Santa Barbara conducted research to understand how the DTS (Dover sole, thornyheads, and sablefish) complex, which consists of four co-occurring species managed under the Pacific Coast Groundfish Fishery Management Plan, could be affected by potential displacement of fishing effort from planned OWF development off the coast of California. Scroll to explore some of the report’s key findings on the impacts of offshore wind lease areas on commercial fishing effort along the California coast. Each chart below is fully interactive: hover, zoom, and pan for more detailed information.
The first U.S. West Coast offshore wind leases cover two areas off the coast of California: Humboldt in the north and Morro Bay in central California. Both areas overlap with the DTS complex, which accounts for 57% of California's groundfish revenues. Understanding the economic implications of OWF implementation for this fishery is critical to designing mitigation strategies that fairly consider and compensate commercial fishers.
We utilized DISPLACE, an agent-based bioeconomic model calibrated to the observed behavior of 214 individual DTS vessels over a 10-year period, to understand how the DTS fishery may be impacted. Our model goes beyond simple footprint analyses by capturing the adaptive nature of fisher behavior, as well as fish population dynamics and fish movement across lease boundaries. Using this model, we compare two scenarios: business-as-usual and closure of the lease areas to fishing.
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We compared fishing effort, the exerted fishing activity on a given area, between our two scenarios and mapped the difference between the two. Red cells indicate an increase in fishing effort in the OWF closure scenario compared to the business-as-usual scenario. Black cells reflect a decrease in effort.
Changes in effort off the coast of California were generally small, lacking observable spatial patterns with the exception of the area around the Humboldt lease area. Despite this regional pattern, net statewide effort did not differ between the two scenarios. DTS catch and revenue declined by 1.6% % and 1.4%, respectively.
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Zooming into the two lease areas, it becomes clear that impacts are concentrated around the Humboldt lease area, where DTS catch and revenue at the Eureka port decline by roughly 3.5%.
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The Morro Bay lease area produces no statistically significant impacts at any port.
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Another important result is that changes in key metrics vary by métier, which we define as the combination of the species assemblage targeted and the gear type used by a fisher. The box plot shows that changes are not uniform across métier, and that DTS trawlers are the only métier type that experiences significant change, as denoted by the asterisks.
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A similar analysis can be done across ports. This box plot tells a similar story to our map: only the Eureka port, which is the port closest to the Humboldt lease closure, experienced significant changes, while the Morro Bay port did not. This contrast has important policy-making implications, as the Morro Bay lease underwent two rounds of siting revisions following community input, whereas Humboldt did not.
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1. Displacement is local, not uniform. Changes in effort concentrate around lease boundaries, reinforcing the importance of well-sited lease areas.
2. Economic exposure is not uniform but can be reduced. By comparing changes across métiers and ports, the results demonstrate that agent-based bioeconomic analyses, conducted during the siting process rather than retrospectively, can identify vulnerable communities and inform boundary adjustments before harm occurs.
3. Community engagement reduces harm. The Morro Bay revisions likely helped mitigate potential economic losses compared to Humboldt. Policymakers should include key stakeholders in the planning process to create lease areas that minimize future losses.